Alec Gallimore

Journal Article Journal of Propulsion and Power · January 1, 2022 The plasma plume properties of a three-channel 100-kW-class nested Hall thruster were measured on xenon propellant for total powers up to 80 kW. The thruster was throttled through all seven available channel combinations for conditions spanning 300 to 500 ... Full text Cite

Performance and High-Speed Characterization of a 100-kW Nested Hall Thruster

Journal Article Journal of Propulsion and Power · January 1, 2022 The performance of a three-channel, 100-kW nested Hall thruster was evaluated on xenon propellant for total powers up to 102 kW. The thruster demonstrated stable operation in all seven available channel combinations at discharge voltages from 300 to 500 V ... Full text Cite

Transient non-classical transport in the hollow cathode plume I: Measurements of time-varying electron collision frequency

Journal Article Plasma Sources Science and Technology · October 1, 2020 Electrostatic probes are employed to measure the time-variations in electron collision frequency due to a large-scale, low-frequency, plasma instability in a high-current hollow cathode plasma discharge (plume mode oscillation). Time-resolved measurements ... Full text Cite

Future directions for electric propulsion research

Journal Article Aerospace · September 1, 2020 The research challenges for electric propulsion technologies are examined in the context of s-curve development cycles. It is shown that the need for research is driven both by the application as well as relative maturity of the technology. For flight qual ... Full text Cite

Operation of a high-power nested hall thruster with reduced cathode flow fraction

Journal Article Journal of Propulsion and Power · January 1, 2020 A high-power nested Hall thruster was operated with cathode flow fractions from 7 to 3% of the total anode flow rate in a two-channel operating configuration at 27 kW total discharge power. The thruster was operated with a state-of-the-art high-current cat ... Full text Cite

Non-invasive in situ measurement of the near-wall ion kinetic energy in a magnetically shielded Hall thruster

Journal Article Plasma Sources Science and Technology · October 21, 2019 The ion velocity distribution functions in the near-wall region of a high-power, 9-kW class magnetically shielded Hall thruster are experimentally characterized to quantify the degree to which the discharge chamber walls are shielded from ion bombardment. ... Full text Cite

Correlation of ion acoustic turbulence with self-organization in a low-temperature plasma

Journal Article Physics of Plasmas · August 1, 2019 The correlation between ion acoustic turbulence (IAT) and self-organization is investigated in a low-temperature, current-carrying xenon plasma. Translating probes are used to measure the dispersion and power spectra of relative fluctuations in the ion sat ... Full text Cite

Enhanced method for analyzing Langmuir probe data and characterizing the Electron Energy Distribution Function (EEDF)

Journal Article Physics of Plasmas · June 1, 2019 Langmuir probes (LPs) are a versatile diagnostic tool that can be used to calculate a multitude of plasma parameters including electron temperature, number density, and the electron energy distribution function (EEDF), especially when the probe theory is p ... Full text Cite

Acceleration region dynamics in a magnetically shielded Hall thruster

Journal Article Physics of Plasmas · February 1, 2019 The influence of the cathode flow fraction and facility background pressure on the acceleration region of a magnetically shielded Hall thruster is experimentally characterized. The location of the acceleration region is measured using laser-induced fluores ... Full text Cite

Time-varying non-classical electron resistivity in a hollow cathode plume

Conference AIAA Propulsion and Energy Forum and Exposition, 2019 · January 1, 2019 An investigation is performed into the time-dependent correlation between the local electron resitivity in a hollow cathode plume and the enhanced electron drag induced by wave-driven turbulence. Emissive, floating, and ion saturation current probes are ap ... Full text Cite

Investigation into the use of cathode flow fraction to mitigate pressure-related facility effects on a magnetically shielded hall thruster

Conference AIAA Propulsion and Energy Forum and Exposition, 2019 · January 1, 2019 The ability to mitigate facility effects by varying the cathode flow fraction of a magnetically-shielded Hall thruster is experimentally investigated. The study is performed on a 9-kW class device operating on both internally and externally mounted cathode ... Full text Cite

On channel interactions in nested Hall thrusters

Journal Article Journal of Applied Physics · April 7, 2018 Nested Hall thrusters use multiple, concentric discharge channels to increase thrust density. They have shown enhanced performance in multi-channel operation relative to the superposition of individual channels. The X2, a two-channel nested Hall thruster, ... Full text Cite

Circuit modeling of rotating magnetic field field-reversed configuration thrusters

Conference 2018 Joint Propulsion Conference · January 1, 2018 A lumped circuit model is presented for the formation and propagation of a rotating magnetic field field-reversed configuration thruster. The driving coils are treated as two lumped circuit inductors operated 90◦ out of phase. The plasma is modeled as an i ... Full text Cite

Update on the nested hall thruster subsystem for the nextstep XR-100 program

Conference 2018 Joint Propulsion Conference · January 1, 2018 Under the NextSTEP program led by Aerojet Rocketdyne in collaboration with NASA Glenn Research Center, the University of Michigan, and the Jet Propulsion Laboratory, the XR-100 100 kW Electric Propulsion system is being developed to Technology Readiness Le ... Full text Cite

Plasma instabilities in the plume of a hollow cathode

Conference 2018 Joint Propulsion Conference · January 1, 2018 Plasma instabilities are spatially characterized in the plume of a 20 A LaB6 hollow cathode using ion saturation probes. The wave measurements are analyzed using a continuous wavelet transform to decompose the signal into three types of oscillations: 50 kH ... Full text Cite

Ion acoustic turbulence in the hollow cathode plume of a hall effect thruster

Conference 2018 Joint Propulsion Conference · January 1, 2018 The ion acoustic turbulence in the plume of a hollow cathode operating in a Hall effect thruster is experimentally and analytically characterized. A recent theoretical study suggests that the increased resistivity as a result of the acoustic waves may dict ... Full text Cite

Development of an mobile electric propulsion demonstration for STEM outreach

Conference 2018 Joint Propulsion Conference · January 1, 2018 The Plasmadynamics and Electric Propulsion Laboratory at the University of Michigan is developing a mobile-demonstration platform to bring advanced propulsion technologies into high school classrooms in the greater Ann Arbor area. Public outreach is critic ... Full text Cite

Kinetic simulation technique for plasma flow in strong external magnetic field

Journal Article Journal of Computational Physics · December 15, 2017 A technique for the kinetic simulation of plasma flow in strong external magnetic fields was developed which captures the compression and expansion of plasma bound to a magnetic flux tube as well as forces on magnetized particles within the flux tube. This ... Full text Cite

Note: Improved heater design for high-temperature hollow cathodes.

Journal Article The Review of scientific instruments · February 2017 We present an improved heater design for thermionic cathodes using a rhenium filament encased in a boron nitride ceramic sleeve. This heater is relatively simple to fabricate, yet has been successfully used to reliably and repeatably light a lanthanum hexa ... Full text Cite

Expanded thruster mass model incorporating nested Hall thrusters

Conference 53rd AIAA/SAE/ASEE Joint Propulsion Conference, 2017 · January 1, 2017 A mass and cost model developed to aid in the selection of electric propulsion string sizes has been expanded to include the potential benefits of nesting the discharge channels of Hall thrusters. First, an analytical expression for the thruster specific a ... Full text Cite

Simple model for cathode coupling voltage versus background pressure in a hall thruster

Conference 53rd AIAA/SAE/ASEE Joint Propulsion Conference, 2017 · January 1, 2017 A simple model is developed to capture the effect of background pressure on the cathode coupling voltage in a Hall effect thruster. Only the voltage drop from the thruster plume to the cathode exit plane is considered as the voltage drop inside the cathode ... Full text Cite

Passive high-speed imaging of ion acoustic turbulence in a hollow cathode

Conference 53rd AIAA/SAE/ASEE Joint Propulsion Conference, 2017 · January 1, 2017 A passive, non-invasive plasma diagnostic is developed and validated to estimate the dispersion of electric propulsion plasmas. This new technique uses a Silicon photomultiplier (SiPM) to measure fluctuations in light intensity to estimate the dispersion o ... Cite

Investigation of channel interactions in nested hall thruster

Journal Article Journal of Propulsion and Power · January 1, 2017 Full text Cite

Investigation of channel interactions in a nested hall thruster part II: Probes and performance

Conference 52nd AIAA/SAE/ASEE Joint Propulsion Conference, 2016 · January 1, 2016 Divergence angle and thrust measurements for a nested Hall thruster in different operating modes are presented. The X2 thruster, a two-channel nested Hall thruster, was run in both single channel and dual-channel modes. The divergence angle for each channe ... Full text Cite

Investigation of channel interactions in a nested hall thruster part I: Acceleration region velocimetry

Conference 52nd AIAA/SAE/ASEE Joint Propulsion Conference, 2016 · January 1, 2016 Velocity distribution function maps were acquired using laser-induced uorescence on the centerline of each channel in a two-channel nested Hall thruster. The inner channel velocity distribution maps showed that the acceleration mechanism behaves differentl ... Full text Cite

Mode transitions in hall-effect thrusters induced by variable magnetic field strength

Journal Article Journal of Propulsion and Power · January 1, 2016 Mode transitions in a 6 kW laboratory Hall-effect thruster were induced by varying the magnetic field intensity while holding all other operating parameters constant. Ultrafast imaging, discharge current, and thrust measurements were used to characterize t ... Full text Cite

Time-resolved laser-induced fluorescence measurements in the plume of a 6 kw Hall thruster with unperturbed oscillations

Conference ICOPS/BEAMS 2014 - 41st IEEE International Conference on Plasma Science and the 20th International Conference on High-Power Particle Beams · January 16, 2015 Full text Cite

Mode transition characteristics and oscillation frequencies in Hall Effect Thrusters

Conference ICOPS/BEAMS 2014 - 41st IEEE International Conference on Plasma Science and the 20th International Conference on High-Power Particle Beams · January 16, 2015 Full text Cite

Discharge oscillation mode transition of a Hall thruster

Conference ICOPS/BEAMS 2014 - 41st IEEE International Conference on Plasma Science and the 20th International Conference on High-Power Particle Beams · January 16, 2015 Full text Cite

Azimuthal spoke propagation in hall effect thrusters

Journal Article IEEE Transactions on Plasma Science · January 1, 2015 Spokes are azimuthally propagating perturbations in the plasma discharge of Hall effect thrusters (HETs) that travel in the E × B direction. The mechanisms for spoke formation are unknown, but their presence has been associated with improved thruster perfo ... Full text Cite

Perturbation analysis of ionization oscillations in Hall effect thrusters

Journal Article Physics of Plasmas · December 1, 2014 A perturbation analysis of ionization oscillations, which cause low frequency oscillations of the discharge plasma, in Hall effect thrusters is presented including the electron energy equation in addition to heavy-species transport. Excitation and stabiliz ... Full text Cite

Mode transition of a Hall thruster discharge plasma

Journal Article Journal of Applied Physics · May 28, 2014 A Hall thruster is a cross-field plasma device used for spacecraft propulsion. An important unresolved issue in the development of Hall thrusters concerns the effect of discharge oscillations in the range of 10-30 kHz on their performance. The use of a hig ... Full text Cite

Implementation and initial validation of a 100-kW class nested-channel Hall thruster

Conference 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference 2014 · January 1, 2014 The X3 is a 100-kW class nested-channel Hall thruster developed by the Plasmady- namics and Electric Propulsion Laboratory at the University of Michigan in collaboration with the Air Force Research Laboratory and NASA. The cathode, magnetic circuit, boron ... Full text Cite

Mode transitions in magnetically shielded hall effect thrusters

Conference 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference 2014 · January 1, 2014 A mode transition study is conducted in magnetically shielded thrusters where the magnetic field magnitude is varied to induce mode transitions. Three different oscillatory modes are identified with the 20-kW NASA-300MS-2 and the 6-kW H6MS: Mode 1) global ... Full text Cite

A cavity ring-down spectroscopy sensor for real-time Hall thruster erosion measurements

Journal Article Review of Scientific Instruments · January 1, 2014 A continuous-wave cavity ring-down spectroscopy sensor for real-time measurements of sputtered boron from Hall thrusters has been developed. The sensor uses a continuous-wave frequency-quadrupled diode laser at 250 nm to probe ground state atomic boron spu ... Full text Cite

Performance of a helicon Hall thruster operating with xenon, argon, and nitrogen

Journal Article Journal of Propulsion and Power · January 1, 2014 The helicon Hall thruster is a two-stage thruster that was developed to investigate whether a radio frequency ionization stage can improve the overall efficiency of a Hall thruster operating at high thrust and low specific impulse. This paper describes an ... Full text Cite

Validation and evaluation of a novel time-resolved laser-induced fluorescence technique

Journal Article Review of Scientific Instruments · January 1, 2014 We present a novel technique to measure time-resolved laser-induced fluorescence signals in plasma sources that have a relatively constant Fourier spectrum of oscillations in steady-state operation, but are not periodically pulsed, e.g., Hall thrusters. Th ... Full text Cite

Mode transitions in Hall effect thrusters

Conference 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference · September 16, 2013 Mode transitions have been commonly observed in Hall Effect Thruster (HET) operation where a small change in a thruster operating parameter such as discharge voltage, magnetic field or mass flow rate causes the thruster discharge current mean value and osc ... Cite

Plasma oscillation effects on nested Hall thruster operation and stability

Conference IEEE Aerospace Conference Proceedings · June 12, 2013 High-power Hall thrusters capable of throughput on the order of 100 kW are currently under development, driven by more demanding mission profiles and rapid growth in on-orbit solar power generation capability. At these power levels the nested Hall thruster ... Full text Cite

Hall thruster plume measurements from High-speed Dual Langmuir Probes with Ion Saturation Reference

Conference IEEE Aerospace Conference Proceedings · June 12, 2013 The plasma plume of a 6 kW Hall Effect Thruster (HET) has been investigated in order to determine time-averaged and time-resolved plasma properties in a 2-D plane. HETs are steady-state devices with a multitude of kilohertz and faster plasma oscillations t ... Full text Cite

CO2 dissociation in an atmospheric pressure plasma/catalyst system: A study of efficiency

Journal Article Plasma Sources Science and Technology · February 1, 2013 The continual and increasing use of fossil fuels throughout the world has advanced concerns of atmospheric carbon dioxide (CO2) concentrations, causing a swell of scientific interest to ease the predicted effects of global warming. This work experimentally ... Full text Cite

Mode transitions in hall effect thrusters

Conference 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference · January 1, 2013 Mode transitions have been commonly observed in Hall Effect Thruster (HET) operation where a small change in a thruster operating parameter such as discharge voltage, magnetic field or mass flow rate causes the thruster discharge current mean value and osc ... Full text Cite

Interior and near-wall ion velocity distribution functions in the H6 Hall thruster

Journal Article Journal of Propulsion and Power · January 1, 2013 This paper presents the results of a two-axis laser-induced fluorescence velocimetry study of singly charged xenon in the interior and near the channel walls of the H6 Hall thruster. The thruster has a nominal operating discharge power of 6 kW and has been ... Full text Cite

Performance and probe measurements of a radio-frequency plasma thruster

Journal Article Journal of Propulsion and Power · January 1, 2013 The performance of a radio-frequency plasma thruster is evaluated using a displacement-type, inverted-pendulum thrust stand in the Large Vacuum Test Facility at the University of Michigan. A radio-frequency generator supplies up to 2000 W to the radio-freq ... Full text Cite

Design and results of a microwave-driven gasdynamic mirror experiment

Journal Article Journal of Propulsion and Power · January 1, 2013 The gasdynamic mirror is a magnetic confinement device that has been proposed as a concept that could form the basis of a spacecraft propulsion system by accelerating its ionized propellant without the endurance limitations imposed by electrodes. The geome ... Full text Cite

Electric propulsion of a different class: The challenges of testing for megawatt missions

Conference 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2012 · December 1, 2012 Currently, there is great interest in the development of high-power electric propulsion (EP) devices that can be employed in missions requiring >100 kW levels of propulsive power. Of the candidates for such thrusters, the Nested-channel Hall thruster (NHT) ... Cite

Performance of a helicon hall thruster operating with xenon, argon, and nitrogen

Conference 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2012 · December 1, 2012 The Helicon Hall Thruster (HHT) is a two-stage thruster that was developed to investigate whether a radiofrequency ionization stage can improve the overall efficiency of a Hall thruster operating at high thrust and low specific impulse. This experiment mea ... Cite

Hydrogen production from methane using an RF plasma source in total nonambipolar flow

Journal Article Plasma Sources Science and Technology · February 1, 2012 A radio-frequency (RF) helicon plasma reaction chamber (HPRC) is developed and used to decompose methane gas into high-purity hydrogen gas and solid carbon in the form of graphite. A single-turn (m = 0) helicon antenna, operated at 13.56MHz, and a 100G dip ... Full text Cite

A low-cost optical approach to evaluate the Life time of Hall thruster discharge channel

Conference 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2012 · January 1, 2012 This paper will present a novel procedure for performing accelerated wear test on Hall thruster discharge channels. The procedure takes advantage of a number of recent advances in optical diagnostics that have enabled increasingly accurate non-intrusive de ... Full text Cite

Measurement of cross-field electron current in a Hall thruster due to rotating spoke instabilities

Conference 47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2011 · December 1, 2011 The first direct experimental measurements of electron current due to rotating spokes in a modern highpower Hall thruster are presented. A segmented anode consisting of 12 equally spaced azimuthal sections has been retrofitted onto the H6 6-kW class Hall t ... Cite

EEDF control through gas injection into a plasma plume

Conference 38th EPS Conference on Plasma Physics 2011, EPS 2011 - Europhysics Conference Abstracts · December 1, 2011 Electron Energy Distribution Function (EEDF) measurements were made in a magnetically enhanced, Inductively Coupled Plasma (ICP) with and without the introduction of an axially injected neutral jet of argon gas with a small relative flow. A lab-built RF co ... Cite

Predictive control of plasma kinetics: Time-resolved measurements of inert gas mixing in a hollow cathode discharge

Conference 62nd International Astronautical Congress 2011, IAC 2011 · December 1, 2011 Improved Hall-effect Thruster (HET) efficiency would enable more extensive cost-capped, Discovery class NASA missions such as robotic missions to Mars and near-Earth asteroids to perform round trip sample-returns. HET efficiency would be further improved i ... Cite

Rotating spoke instabilities in Hall thrusters

Journal Article IEEE Transactions on Plasma Science · November 1, 2011 High-speed imaging of a Hall thruster plume reveals near-omnipresent rotating regions of elevated light emission, dubbed rotating spokes, in the annular thruster discharge channel. Azimuthal oscillations have long been suggested to induce cross-field elect ... Full text Cite

Efficiency of CO 2 dissociation in a radio-frequency discharge

Journal Article Plasma Chemistry and Plasma Processing · February 1, 2011 One possible solution to mitigating the effects of high atmospheric concentrations of carbon dioxide (CO 2) is the use of a plasma source to break apart the molecule into carbon monoxide (CO) and oxygen. This work experimentally investigates the efficiency ... Full text Cite

Initial cavity ring-down density measurement on a 6-kW Hall thruster

Conference 47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2011 · January 1, 2011 We present the initial results from a cavity ring-down sensor for measuring the density of sputtered boron atoms originating from the discharge channel of a 6-kW Hall thruster. The sensor traps 250 nm light in a high-finesse cavity to greatly increase its ... Full text Cite

Experimental characterization of the near-wall plasma in a 6-kW hall thruster and comparison to simulation

Conference 47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2011 · January 1, 2011 In order to better understand interactions between the plasma and channel walls of a Hall thruster, the near-wall plasma was characterized within the H6 Hall thruster using five flush-mounted Langmuir probes. These probes were placed within the last 15% of ... Full text Cite

Evaluation of facility effects on ion migration in a hall thruster plume

Journal Article Journal of Propulsion and Power · January 1, 2011 Anested Faraday probe was designed and fabricated to assess facility effects in a systematic study of ion migration in a Hall thruster plume. Angular distributions of ion current density were studied at 8, 12, 16, and 20 thruster diameters downstream of a ... Full text Cite

Neutral flow evolution in a six-kilowatt hall thruster

Journal Article Journal of Propulsion and Power · January 1, 2011 Laser-induced fluorescence velocimetry measurements obtained from the interior of a 6-kW Hall thruster using the Xe I 6s[3/2]02 → 6p[3=2]2 transition at 823.4 nm (vacuum) and the Xe I 6s'[1/2]01 → 6p'[3/2]2 transition at 834.9 nm (vacuum) are presented. Th ... Full text Cite

High-speed dual Langmuir probe

Journal Article Review of Scientific Instruments · July 1, 2010 In an effort to temporally resolve the electron density, electron temperature, and plasma potential for turbulent plasma discharges, a unique high-speed dual Langmuir probe (HDLP) has been developed. A traditional single Langmuir probe of cylindrical geome ... Full text Cite

Temporal limits of a rapidly swept Langmuir probe

Journal Article Physics of Plasmas · July 1, 2010 The finite, electrostatically achievable, temporal resolution of plasma properties from a turbulent discharge is limited by an array of effects wherein the theory of Langmuir probes breaks down. Formulations for the particle transit time, sheath formation ... Full text Cite

A CubeSat design to validate the virtex-5 FPGA for spaceborne image processing

Conference IEEE Aerospace Conference Proceedings · June 2, 2010 The Earth Sciences Decadal Survey identifies a multiangle, multispectral, high-accuracy polarization imager as one requirement for the Aerosol-Cloud-Ecosystem (ACE) mission. JPL has been developing a Multiangle SpectroPolarimetric Imager (MSPI) as a candid ... Full text Cite

Evaluation of ion collection area in Faraday probes

Journal Article Review of Scientific Instruments · June 1, 2010 A Faraday probe with three concentric rings was designed and fabricated to assess the effect of gap width and collector diameter in a systematic study of the diagnostic ion collection area. The nested Faraday probe consisted of two concentric collector rin ... Full text Cite

Developing a reduced gravity testbed for the nanoparticle field extraction thruster

Conference 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2009 The Nanoparticle Field Extraction Thruster (NanoFET) is an electric propulsion device under development at the University of Michigan to electrostatically charge and accelerate micro- and nano-particle propellant. During the 2008-2009 academic year, underg ... Cite

Near-wall plasma properties and EEDF measurements of a 6-kW Hall thruster

Conference 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2009 In preparation for in-depth internal wall measurements for erosion and electron mobility studies, a flush-mounted Langmuir probe and emissive probe were used to characterize the near-wall region near the exit plane of a 6-kW Hall thruster. Various plasma p ... Cite

Fusing spatially and temporally separated single-point turbulent plasma flow measurements into two-dimensional time-resolved visualizations

Conference 2009 12th International Conference on Information Fusion, FUSION 2009 · November 18, 2009 Single-point measurements of time-resolved plasma density fluctuations are collected throughout a planar region of the exhaust plume downstream from a Hall effect thruster. A matrix of empirical discrete time transfer functions is created between the thrus ... Cite

A study of reaction kinetics of a water plasma using a 0-D global kinetic model

Conference IEEE International Conference on Plasma Science · November 10, 2009 Full text Cite

Micro/nano-particle electrostatic accelerator for electric propulsion

Conference IEEE International Conference on Plasma Science · November 10, 2009 Full text Cite

Characterization of a water radiofrequency plasma - An experimental investigation

Conference IEEE International Conference on Plasma Science · November 10, 2009 Full text Cite

High-speed planar plasma density measurements in a hall thruster plume

Conference IEEE International Conference on Plasma Science · November 10, 2009 Full text Cite

Operating a radio-frequency plasma source on water vapor

Journal Article Review of Scientific Instruments · September 9, 2009 A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper d ... Full text Cite

Method for analyzing E×B probe spectra from Hall thruster plumes

Journal Article Review of Scientific Instruments · July 17, 2009 Various methods for accurately determining ion species' current fractions using E×B probes in Hall thruster plumes are investigated. The effects of peak broadening and charge exchange on the calculated values of current fractions are quantified in order to ... Full text Cite

Using a helicon source to simulate atmospheric re-entry plasma densities and temperatures in a laboratory setting

Journal Article Plasma Sources Science and Technology · July 10, 2009 The purpose of this research is to develop a plasma system capable of reproducing plasma densities found during atmospheric re-entry of a capsule. We developed a 150 mm diameter helicon source at the University of Michigan Plasmadynamics and Electric Propu ... Full text Cite

Electrostatic charging of micro- and nano-particles for use with highly energetic applications

Journal Article Journal of Electrostatics · February 1, 2009 Electrostatically charging spherical and cylindrical conducting particles against an electrode with an applied electric field is investigated both theoretically and experimentally as a method of charging micro- and nano-particles for use with a variety of ... Full text Cite

Obtaining velocity distribution using a xenon ion line with unknown hyperfine constants

Conference 40th AIAA Plasmadynamics and Lasers Conference · January 1, 2009 We present and validate a method for extracting velocity distribution functions from laser-induced fluorescence measurements obtained using a xenon ion line with unknown hyperfine constants. The method involves a direct deconvolution of intermodulated expe ... Full text Cite

Hall thruster and VASIMR VX-100 force measurements using a plasma momentum flux sensor

Conference 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition · January 1, 2009 The accuracy of a plasma impact force sensor was compared to that of the more commonly used inverted pendulum thrust stand using a 5 kW Xe Hall effect thruster (HET). An improved plasma momentum flux sensor (PMFS) was designed and constructed based on a pr ... Full text Cite

Experimental results for communications blackout amelioration using crossed electric and magnetic fields

Journal Article Journal of Spacecraft and Rockets · January 1, 2009 As a vehicle reenters the atmosphere or travels at hypersonic speeds within it, a bow shock forms around the leading edge of the vehicle. The air is superheated as it passes through the shock wave and becomes ionized. This plasma layer prevents the transmi ... Full text Cite

Methodology and historical perspective of a hall thruster efficiency analysis

Journal Article Journal of Propulsion and Power · January 1, 2009 A Hall thruster performance architecture was developed based on separation of the total thrust directed along thruster centerline into mass-weighted and momentum-weighted terms. With this formulation, the total thruster efficiency equation was analytically ... Full text Cite

Specific charge control for micro/nano-particle electrostatic propulsion

Conference 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2009 Contact charging of micro- and nano-particles affords the Nanoparticle Field Extraction Thruster (NanoFET) flexibility to adjust its propellant's specific charge. This flexibility permits NanoFET to tune its propulsive performance by adjusting the charging ... Full text Cite

Temporally and spatially resolved measurements in the plume of clustered Hall thrusters

Conference 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2009 A High-speed Dual Langmuir Probe system (HDLP) and a high-speed camera tracked 19.6-kHz waves of ionized propellant emitted by the unsteady ionization process or "breathing mode" of a cluster of Hall thrusters. Two 600-W, low-power Hall thrusters were oper ... Full text Cite

Laser-induced fluorescence of singly-charged xenon inside a 6-kW Hall thruster

Conference 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2009 We present laser-induced fluorescence velocimetry measurements of the 5d[4]7/2 → 6p[3]°5/2 transition for singly-charged xenon (Xe II) at 834.953 nm (vacuum) inside and in the near-field plume of a 6-kW Hall thruster. The thruster has a nominal operating d ... Full text Cite

Validating a plasma momentum flux sensor to an inverted pendulum thrust stand

Journal Article Journal of Propulsion and Power · January 1, 2009 The accuracy of a plasma impact force sensor was compared with that of the more commonly used inverted pendulum thrust stand using a 5 kW Xe Hall effect thruster. An improved plasma momentum flux sensor was designed and constructed based on a previous desi ... Full text Cite

Angularly-resolved E×B probe spectra in the plume of a 6-kW Hall thruster

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 An E×B probe was used to characterize the angular distribution of multiply-charged ions in the plume of a 6-kW Hall thruster operating at discharge voltages of 150-600 V, and anode mass flow rates of 10-30 mg/s. The local ion current fractions were measure ... Cite

A method of measuring transient plume properties

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 In an effort to study the transient fluctuations of plasma properties downstream of a Hall Effect Thruster (HET) on a microsecond timescale, a high-speed Langmuir probe measurement system is developed and tested. A high-voltage (±225 V), broadband (DC - 2 ... Cite

Developmental progress of the Nanoparticle Field Extraction Thruster

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 The Nanoparticle Field Extraction Thruster (NanoFET) is an electrostatic accelerator technology currently under development at the University of Michigan to accelerate micro-/nano-particles. The concept exists in two configurations: the liquid configuratio ... Cite

Validating a plasma momentum flux sensor against an inverted pendulum thrust stand

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 The accuracy of a plasma impact force sensor was compared to that of the more commonly used inverted pendulum thrust stand using a 5 kW Xe Hall thruster. A plasma momentum flux sensor (PMFS) was designed and constructed based on a previous NASAMarshall Spa ... Cite

Method for analyzing E×B probe spectra from Hall thruster plumes

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 Various methods for accurately determining ion species' current fractions using E×B probes in Hall thruster plumes are investigated. The effects of peak broadening and charge exchange on the calculated values of current fractions are quantified in order to ... Cite

Nanoparticle field extraction thruster (nanoFET): Introduction to, analysis of, and experimental results from the "No-liquid" configuration AIAA-2008-5097

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 This paper introduces a nanoparticle field extraction thruster (nanoFET) concept that does not depend on the liquid delivery of micro and nano-particles for extraction and acceleration. The no-liquid approach potentially provides important advantages such ... Cite

High-sensitivity boron nitride sputter erosion measurements by continuous-wave cavity ring-down spectroscopy

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 Sputter erosion of boron nitride (BN) plays a key life-limiting role in many Hall thrusters. We report on the development of cavity ring-down spectroscopy (CRDS) as a sensitive and accelerated diagnostic for sputter erosion. The measurement approach is bas ... Cite

Interpretation of wall-mounted probe characteristics in Hall thrusters

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2008 Wall-mounted Langmuir probes are a promising internal diagnostic for Hall thrusters that can help understand critical plasma-wall interactions. However, the non-ideal environment within the discharge channel can complicate the implementation and interpreta ... Cite

Numerical simulation of the Zeeman effect in neutral xenon from NIR diode-laser spectroscopy

Journal Article Journal of Applied Physics · August 12, 2008 We present a numerical method for simulating neutral xenon absorption spectra from diode-laser spectroscopy of the Zeeman-split 6S′[1/2] →6P′[1/2] line at 834.682 nm-air in a galvatron's plasma. To simulate the spectrum, we apply a Voigt profile to a spect ... Full text Cite

An ion thruster internal discharge chamber electrostatic probe diagnostic technique using a high-speed probe positioning system

Journal Article Review of Scientific Instruments · February 7, 2008 Extensive resources have been allocated to diagnose and minimize lifetime-limiting factors in gridded ion thrusters. While most of this effort has focused on grid erosion, results from wear tests indicate that discharge cathode erosion may also play an imp ... Full text Cite

Guest Editorial: Special Issue on Plasma Propulsion

Journal Article IEEE Transactions on Plasma Science · January 1, 2008 Full text Cite

Alpha particle dynamics in muon-boosted fusion propulsion system

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2008 In a previous paper,1 we demonstrated that negative muons resulting from antiproton annihilation in a relatively cold deuterium-tritium (DT) plasma confined in a gasdynamic mirror (GDM) can result in catalyzing on average over 100 fusion reactions. The alp ... Full text Cite

Laser-induced fluorescence of singly-charged xenon in a 6-kW Hall thruster plume

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2008 We present laser-induced fluorescence velocimetry measurements of the 5d[4]7/2 → 6p[3]°5/2 transition for singly-charged xenon (Xe II) at 834.953 nm (vacuum) in the near-field plume of a 6-kW Hall thruster. Axial velocity profiles were obtained at six loca ... Full text Cite

Reduced gravity testing of the Nanoparticle Field Extraction Thruster

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2008 During the 2006-2007 and 2007-2008 academic calendar years, C-9 NanoBLUE, a team of undergraduates within the University of Michigan's Student Space Systems Fabrication Laboratory, investigated the effects of a reduced gravity environment on the Nanopartic ... Full text Cite

Statistical analysis of the acceleration zone location in hall thrusters

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2008 This study uses a stepwise regression strategy to examine the interaction between the Hall thruster operating parameters and the location of the acceleration zone. The results of the regression are then linked to the Hall thruster physics, specifically the ... Full text Cite

Plasma potential measurements in the discharge channel of a 6-kW Hall thruster

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2008 In an effort to understand the role of neutral flow dynamics in the operation of Hall thrusters, a floating emissive probe was used to measure the plasma potential, electric field, and electron temperature in the discharge channel of a 6-kW Hall thruster o ... Full text Cite

Langmuir probe measurements in the discharge channel of a 6-kW Hall thruster

Conference 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2008 In an effort to understand the role of neutral flow dynamics in the operation of Hall thrusters, a cylindrical Langmuir probe was used to measure the electron temperature, floating potential, and ion number density in the discharge channel of a 6-kW Hall t ... Full text Cite

Measurement of 30-centimeter ion thruster discharge cathode erosion

Journal Article Journal of Propulsion and Power · January 1, 2008 Relative erosion rates of the discharge cathode assembly of a 30-cm ion engine are measured using laser-induced fluorescence. Molybdenum and tungsten erosion products are interrogated downstream of the discharge cathode assembly during beam extraction. Ero ... Full text Cite

Dormant cathode erosion in a multiple-cathode gridded ion thruster

Journal Article Journal of Propulsion and Power · January 1, 2008 A rectangular gridded ion thruster discharge chamber is investigated for operation with multiple discharge cathode assemblies. The multiple-cathode approach attempts to increase thruster throughput and lifetime by operating three discharge cathode assembli ... Full text Cite

Far-field species distribution measurements on the BHT-600 hall thruster cluster

Conference Collection of Technical Papers - 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference · December 10, 2007 Measurements via the Top Hat Electric Propulsion Plume Analyzer (TOPAZ) on the Busek BHT-600 Hall thruster cluster are presented. TOPAZ incorporates a 'top ha design with an analyzer constant of 100 resulting in a wide energy-range capability and high angu ... Cite

The use of boron nitride for field effect electron emission

Conference Collection of Technical Papers - 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference · December 10, 2007 Boron nitride in the cubic phase has been considered a potential candidate for use as electron field emitters. This paper highlights results and challenges in characterizing boron nitride's suitability for use in electric propulsion applications and in des ... Cite

Nanoparticle electric propulsion for space exploration

Conference AIP Conference Proceedings · December 1, 2007 A new electrostatic thruster technology is under development at the University of Michigan using nanoparticles as propellant with micro-and nano-electromechanical systems. Termed the nanoparticle field extraction thruster (nanoFET), this highly integrated ... Full text Cite

A path based approach for optimizing low-thrust interplanetary trajectories

Conference Advances in the Astronautical Sciences · December 1, 2007 We use a path based approach to find optimal spacecraft trajectories. The algorithm searches for the control and states that generate a trajectory that is dynamically consistent. The path functions allow ephemeris constraints to be directly enforced ensuri ... Cite

The use of boron nitride for field effect electron emission

Conference Technical Digest of the 20th International Vacuum Nanoelectronics Conference, IVNC 07 · December 1, 2007 Full text Cite

Ion energy measurements near a dormant cathode in a multiple-cathode gridded ion thruster

Journal Article Physics of Plasmas · April 8, 2007 A rectangular ion thruster discharge chamber was investigated for operation with multiple discharge cathode assemblies (DCAs). The multiple cathode approach attempts to increase thruster throughput and lifetime by operating three DCAs sequentially, possibl ... Full text Cite

Effects of cathode configuration on hall thruster cluster plume properties

Journal Article Journal of Propulsion and Power · January 1, 2007 Clusters of Hall thrusters may be used to produce electric propulsion systems capable of operating at power levels in excess of the current state of the art One of the key factors to be considered in determining the optimum cluster architecture is the conf ... Full text Cite

Erosion processes of the discharge cathode assembly of ring-cusp gridded ion thrusters

Journal Article Journal of Propulsion and Power · January 1, 2007 An ion-thruster discharge-cathode-assembly erosion theory is presented based on near-discharge-cathodeassembly NSTAR plasma measurements and experimental results for propellant flow rate effects on ion number density. The plasma-potential structures are us ... Full text Cite

Hydrodynamic modeling of krypton and xenon propellant performance in a hall thruster

Conference Collection of Technical Papers - 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference · January 1, 2007 An axisymmetric hydrodynamic model of the plasma flow within a Hall thruster channel is used to model the differences between krypton and xenon propellants. Krypton offers a higher specific impulse and lower cost than xenon, but its overall efficiency is o ... Full text Cite

Experimental results and modeling advances in the study of the nanoparticle field extraction thruster

Conference Collection of Technical Papers - 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference · January 1, 2007 This paper presents experimental results and modeling advances concerning the nanoparticle Field Extraction Thruster (nanoFET) concept under development at the University of Michigan. The nanoFET concept offers an electric propulsion approach that can have ... Full text Cite

Field asymmetry and thrust control in the GDM fusion propulsion system

Conference Collection of Technical Papers - 43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference · January 1, 2007 One of the notable attributes of the Gasdynamic Mirror (GDM) fusion propulsion system is the fact that it lends itself readily to thrust control due to asymmetry in the magnetic field configuration. GDM is a magnetic plasma confinement device that has been ... Full text Cite

Performance and flatness of a multiple-cathode, rectangular ion thruster discharge chamber

Journal Article Journal of Propulsion and Power · January 1, 2007 Results from the extended life test of the Deep Space One flight spare ion engine show that enlargement of the discharge cathode assembly orifice due to erosion of the orifice by ion bombardment limits the throughput of the ion thruster, and therefore limi ... Full text Cite

Performance characteristics of a cluster of 5-kW laboratory hall thrusters

Journal Article Journal of Propulsion and Power · January 1, 2007 Performance characteristics of a 2 × 1 cluster of 5-kW Hall effect thrusters are investigated. The cluster and each thruster are evaluated over the power range of 1.5-6 kW at three facility pumping speeds. Analysis of the monolithic thrust measurements sho ... Full text Cite

Hall thruster cluster operation with a shared cathode

Journal Article Journal of Propulsion and Power · January 1, 2007 The effects of cluster cathode sharing on the performance of a 2 × 1 cluster of 5-kW Hall effect thrusters are investigated. The cluster is operated from 1.5-6 kW over a range of backpressures from 4.7 × 10-4 Pa Xe (3.5 × 10-6 torr Xe) to 1.2 × 10-3 Pa Xe ... Full text Cite

Dynamic electromagnetic field measurements of clustered Hall thrusters

Conference Collection of Technical Papers - AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference · December 1, 2006 In an effort to verify the existence of and study the characteristics of the dynamic magnetic fields generated by supplying inner and outer coil Hall thruster electromagnets with wide bandwidth (DC to 200 kHz) currents, B-dot probe experiments have been pe ... Cite

Nanoparticle electric propulsion: Experimental results

Conference Collection of Technical Papers - AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference · December 1, 2006 This paper presents experimental results concerning the nanoparticle Field Extraction Thruster (nanoFET) concept under development at the University of Michigan. The nanoFET concept offers an electric propulsion approach that can have a highly adjustable c ... Cite

Development of an annular helicon source for electric propulsion applications

Conference Collection of Technical Papers - AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference · December 1, 2006 The performance of typical electrostatic propulsion systems, such as the Hall thruster, is limited in part by inefficiencies in the electron bombardment ionization process. These limitations become especially pronounced at the operating conditions required ... Cite

Theoretical aspects of nanoparticle electric propulsion

Conference Collection of Technical Papers - AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference · December 1, 2006 The nanoparticle field extraction thruster (nanoFET), using charged nanoparticles to generate propulsive thrust, is currently under development at the University of Michigan. This paper discusses the theoretical aspects of nanoFET operation, including part ... Cite

Automating trade studies for optimal interplanetary electric propulsion missions

Conference Advances in the Astronautical Sciences · December 1, 2006 Conducting preliminary trade studies are critical in determining the feasibility of a mission and identifying how various spacecraft systems will scale. We develop an algorithm for automating trade studies for electric propulsion interplanetary missions. T ... Cite

Internal plasma potential measurements of a Hall thruster using plasma lens focusing

Journal Article Physics of Plasmas · November 7, 2006 Magnetic field topology has been found to be a central design concern for high-efficiency Hall thrusters. For future improvements in Hall thruster design, it is necessary to better understand the effects that magnetic field topology has on the internal pla ... Full text Cite

Internal plasma potential measurements of a Hall thruster using xenon and krypton propellent

Journal Article Physics of Plasmas · October 9, 2006 For krypton to become a realistic option for Hall thruster operation, it is necessary to understand the performance gap between xenon and krypton and what can be done to reduce it. A floating emissive probe is used with the Plasmadynamics and Electric Prop ... Full text Cite

Top hat electrostatic analyzer for far-field electric propulsion plume diagnostics

Journal Article Review of Scientific Instruments · February 6, 2006 The design, development, and testing of the top hat electric propulsion plume analyzer (TOPAZ) are presented for far-field electric propulsion plume diagnostics. The trend towards high-power thruster development will require plume diagnostic techniques cap ... Full text Cite

Magnetically filtered Faraday probe for measuring the ion current density profile of a Hall thruster

Journal Article Review of Scientific Instruments · February 6, 2006 The ability of a magnetically filtered Faraday probe (MFFP) to obtain the ion current density profile of a Hall thruster is investigated. The MFFP is designed to eliminate the collection of low-energy, charge-exchange (CEX) ions by using a variable magneti ... Full text Cite

Internal langmuir probe mapping of a hall thruster with xenon and krypton propellant

Conference Collection of Technical Papers - AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference · January 1, 2006 A cylindrical Langmuir probe is used with the Plasmadynamics and Electric Propulsion Laboratory High-speed Axial Reciprocating Probe system to map the plasma properties internal to the NASA-173Mv1 Hall thruster using xenon and krypton propellant. Measureme ... Full text Cite

Maximizing payload mass fractions of spacecraft for interplanetary electric propulsion missions

Journal Article Journal of Spacecraft and Rockets · January 1, 2006 Optimization of a spacecraft's interplanetary trajectory and electric propulsion system remains a complex and difficult problem. Simultaneously solving for the optimal trajectory, power level, and exhaust velocity can be difficult and time consuming. If th ... Full text Cite

Erosion processes of the discharge cathode assembly of ring-cusp gridded ion thrusters

Conference Collection of Technical Papers - 37th AIAA Plasmadynamics and Lasers Conference · January 1, 2006 An ion thruster discharge cathode assembly (DCA) erosion theory is presented based on near-DCA NSTAR plasma measurements and experimental results for propellant flow rate effects on ion number density. The plasma potential structures are utilized in an ion ... Full text Cite

MEMS gate structures for electric propulsion applications

Conference Collection of Technical Papers - AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference · January 1, 2006 A MEMS gate prototype is under development to extract and accelerate charged particles for use with Held emission cathodes and the nanoparticle field extraction thruster at the University of Michigan. Preliminary simulations suggest the desirability of a u ... Full text Cite

Krypton performance optimization in high-voltage hall thrusters

Journal Article Journal of Propulsion and Power · January 1, 2006 Krypton is being considered for use as a propellant to find approximate anode flow rates and discharge voltages for Hall thrusters. The NASA-173Mv 1 Hall effect thruster was used to characterize the performance of the krypton propellant. The thruster used ... Full text Cite

High-specific impulse Hall thrusters, part 1: Influence of current density and magnetic field

Journal Article Journal of Propulsion and Power · January 1, 2006 A laboratory-model Hall thruster with a magnetic circuit designed for high-specific impulse (2000-3000 s) was evaluated to determine how current density and magnetic field affect thruster operation. Results have shown for the first time that a minimum curr ... Full text Cite

Ion-energy plume diagnostics on the BHT-600 hall thruster cluster

Journal Article Journal of Propulsion and Power · January 1, 2006 The use of electrostatic analyzers to measure ion energy-to-charge distributions and angular trajectories of plasma exhaust particles for Hall thruster plume diagnostics, is discussed. Electrostatic analyzer consists of a sphere and a concentric shell with ... Full text Cite

Efficiency analysis of a hall thruster operating with krypton and xenon

Journal Article Journal of Propulsion and Power · January 1, 2006 Krypton has recently become the focus of attention in the Hall thruster community because of its relatively large specific impulse compared with xenon and its potential to operate with comparable efficiencies. However, before krypton can be considered a vi ... Full text Cite

Ion collection in Hall thruster plumes

Journal Article Journal of Propulsion and Power · January 1, 2006 The two nude Farade probes of differing design that are used simultaneously to measure the ion current density of a 5 kW Hall thruster are discussed. The ion current density distribution of the 173 Mv1 Hallthruster is measured with two probes over a wide r ... Full text Cite

High-specific impulse Hall thrusters, part 2: Efficiency analysis

Journal Article Journal of Propulsion and Power · January 1, 2006 Performance and plasma measurements of a high-specific impulse (2000-3000 s) Hall thruster were analyzed using a phenomenological performance model that accounted for a partially ionized plasma containing multiply charged ions. Anode efficiency over discha ... Full text Cite

Efficiency analysis of a hall thruster operating with krypton and xenon

Conference 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2005 Krypton has recently become the focus of attention in the Hall thruster community because of its relatively large specific impulse as compared to xenon and its potential to operate with comparable efficiencies. However, before krypton can be considered a v ... Cite

Evaluation and active control of clustered hall thruster discharge oscillations

Conference 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2005 While preliminary experiments with a cluster of four Busek 200-Watt (BHT-200-X3) Closed Drift Hall thrusters indicate reasonable performance scalability from single thruster experiments, cluster plume interactions are believed to give rise to an increased ... Cite

Interstellar probe: Breakthrough science enabled by nuclear propulsion

Journal Article Space Technology · December 1, 2005 It is the purpose of Interstellar Probe (ISP) to follow NASA's exploratory mission to cross the heliospheric boundary regions and, for the first time, enter our extra-solar galactic environment. Interstellar Probe has therefore captured the imagination of ... Cite

The effects of cathode configuration on hall thruster cluster plume properties

Conference 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2005 Clusters of Hall thrusters are being considered for use on a variety of missions requiring electric propulsion systems capable of operating at power levels in excess of the current state of the art. One of the key factors to be considered in determining th ... Cite

Application of dual grids to cold cathode/field effect electron emission

Conference 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2005 This paper will present an analysis of dual grid field emitter technology, illustrating the substantial power savings that can be obtained from existing technologies by controlling the final velocity of emitted electrons. Additionally, using two grids inst ... Cite

Interstellar probe: Breakthrough science enabled by nuclear propulsion

Conference IEEE Aerospace Conference Proceedings · December 1, 2005 1,2The purpose of Interstellar Probe (ISP) is to follow NASA's exploratory mission to cross the heliospheric boundary regions and, for the first time, enter our extra-solar galactic environment. Interstellar Probe has therefore captured the imagination of ... Full text Cite

Plasma properties downstream of a low-power Hall thruster

Journal Article Physics of Plasmas · December 1, 2005 Triple Langmuir probes and emissive probes were used to measure the electron number density, electron temperature, and plasma potential downstream of a low-power Hall thruster. The results show a polytropic relation between electron temperature and electro ... Full text Cite

Experimental investigation of electron collection to solid and slotted tape probes in a high-speed flowing plasma

Journal Article IEEE Transactions on Plasma Science · August 1, 2005 This paper presents the analysis and comparison of measurements of electron current collection to round cylinder, solid tape, and slotted tape electrodynamic-tether samples in a mesosonic flowing plasma. A Hall thruster was used to simulate a flowing unmag ... Full text Cite

Neutral density map of Hall thruster plume expansion in a vacuum chamber

Journal Article Review of Scientific Instruments · May 1, 2005 A neutral background pressure map of the large vacuum test facility (LVTF) is presented. The LVTF is mapped at cold anode flow rates of 5.25, 10.46, and 14.09 mgs. In addition, neutral background pressure maps are created at hot anode (i.e., discharge on) ... Full text Cite

Effect of backpressure on ion current density measurements in hall thruster plumes

Journal Article Journal of Propulsion and Power · January 1, 2005 The effects of facility backpressure and localized electric fields on the measured ion current densities of Hall thrusters are investigated. Langmuir probe measurements are taken in the near-field plasma surrounding a nude Faraday probe, which is located 1 ... Full text Cite

Internal plasma structure measurements of a hall thruster using plasma lens focusing

Conference 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2005 Magnetic field topology has been found to be a central design concern for high-efficiency Hall thrusters. For future improvements in Hall thruster design, it is necessary to better understand the effects that magnetic field topology has on the internal pla ... Full text Cite

Design and operation of a multiple-cathode, high-power, rectangular discharge chamber

Conference 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2005 A high-power, rectangular discharge chamber is being designed by the University of Michigan for operation with multiple discharge cathode assemblies (DCAs). The multiple cathode approach attempts to increase thruster lifetime by operating three DCAs sequen ... Full text Cite

Efficiency analysis of a high-specific impulse hall thruster

Conference 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2004 Performance and plasma measurements of the high-specific impulse NASA-173Mv2 Hall thruster were analyzed using a phenomenological performance model that accounts for a partially-ionized plasma containing multiply-charged ions. Between discharge voltages of ... Cite

Interstellar probe: Breakthrough science enabled by nuclear propulsion

Conference International Astronautical Federation - 55th International Astronautical Congress 2004 · December 1, 2004 It is the purpose of Interstellar Probe (ISP) to follow NASA's exploratory mission to cross the heliospheric boundary regions and, for the first time, enter our extra-solar galactic environment. Interstellar Probe has therefore captured the imagination of ... Cite

On the potential distribution in hall thrusters

Journal Article Applied Physics Letters · September 27, 2004 A model of the plasma flow in the hall thruster channel was developed that takes into account the two-dimensional current conservation effect and relies on some experimental input parameters. The model was used to predict the nonuniform potential distribut ... Full text Cite

Ion-Energy Diagnostics in an SPT-100 Plume from Thrust Axis to Backflow

Journal Article Journal of Propulsion and Power · January 1, 2004 Of primary concern with the integration of Hall thrusters on conventional satellite designs is the possible damaging effect of high-energy exhaust ions impinging upon spacecraft surfaces. This paper reports on measurements of plasma ion-energy distribution ... Full text Cite

Vacuum chamber pressure maps of a hall thruster cold-flow expansion

Journal Article Journal of Propulsion and Power · January 1, 2004 A technique for calibrating a vacuum chamber in terms of pressure to account for elevated back pressure while testing Hall thrusters was presented. As a first step in this process, a neutral gas background pressure map of the Large Vacuum Test Facility (LV ... Full text Cite

Plasma properties in the plume of a hall thruster cluster

Journal Article Journal of Propulsion and Power · January 1, 2004 The Hall thruster cluster is an attractive propulsion approach for spacecraft requiring very high-power electric propulsion systems. Plasma density, electron temperature, and plasma potential data collected with a combination of triple langmuir probes and ... Full text Cite

Overview of electric propulsion research in U.S. academia

Conference 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2003 An overview is presented of electric propulsion research carried out in U.S. academic institutions. Universities in the U.S. are engaged in a wide range of research, varying from fundamental studies in micro thruster concepts, to future flight involving ma ... Cite

Comparison of Discharge plasma parameters in a 30-cm nstar type ion engine with and without beam extraction

Conference 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2003 Double Langmuir probe measurements are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring cusp ion thruster. Discharge plasma data taken with and without beam extraction exhibit ... Cite

Ion species fractions in the far-field plume of a high-specific impulse Hall thruster

Conference 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2003 An ExB probe was used to measure the ion species fractions of Xe+, Xe2+, and Xe3+ in the farfield plume of the NASA-173Mv2 laboratory-model Hall thruster. The thruster was operated at a constant xenon flow rate of 10 mg/s and discharge voltages of 300-900 ... Full text Cite

Ion voltage diagnostics in the far-field plume of a high-specific impulse Hall thruster

Conference 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2003 The effects of the magnetic field and discharge voltage on the far-field plume of the NASA-173Mv2 laboratory-model Hall thruster were investigated. A cylindrical Langmuir probe was used to measure the plasma potential and a retarding potential analyzer was ... Full text Cite

The effects of clustering multiple Hall thrusters on plasma plume properties

Conference 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2003 Clusters of Hall thrusters have been proposed as a means of achieving electric propulsion systems capable of operating at very high power levels. To facilitate testing in existing vacuum facilities, initial tests have focused on a cluster of low-power Buse ... Full text Cite

Low-current, xenon orificed hollow cathode performance for in-space applications

Journal Article Journal of Propulsion and Power · January 1, 2003 An experimental investigation of the operating characteristics of 3.2-mm-diam orificed hollow cathodes was conducted to examine low-current and low flow-rate operation. Cathode power for self-sustaining keeper operation was minimized with an orifice aspect ... Full text Cite

A high-speed probe positioning system for interrogating the discharge plasma of a 30 cm ion thruster

Conference 38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2002 A method for delivery of a symmetric double probe into the discharge chamber of a 30-cm diameter ringcusped ion thruster is discussed. Motivation for direct access of the electrostatic probe to the discharge chamber stems from the need to characterize the ... Cite

The role of magnetic field topography in improving the performance of high-voltage hall thrusters

Conference 38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · December 1, 2002 Investigations of high-voltage Hall thrusters have indicated a peak in the efficiency versus voltage characteristic that limited the maximum efficiency to specific impulses of less than 3000 s. This peak is believed to be primarily a trait of modern magnet ... Cite

Analysis of chamber simulations of long collecting probes in high-speed dense plasmas

Journal Article IEEE Transactions on Plasma Science · October 1, 2002 Chamber tests of simulated electrodynamic tethers (EDTs) of different geometries operating in a dense high-speed plasma are described. The geometries tested and described here are cylindrical and flat-ribbon tape. By moving the probe samples relative to th ... Full text Cite

Considerations on the role of the Hall current in a laboratory-model thruster

Journal Article IEEE Transactions on Plasma Science · April 1, 2002 Hall current magnitude and spatial distribution are presented for the plasma discharge in the University of Michigan/Air Force Research Laboratory P5 5 kW laboratory-model Hall thruster. The data are calculated from direct, probe-based measurements of the ... Full text Cite

The effects of nude faraday probe design and vacuum facility backpressure on the measured ion current density profile of hall thruster plumes

Conference 38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2002 The effects of dissimilar probe design and facility backpressure on the measured ion current densities of Hall thrusters are investigated. JPL and GRC designed nude Faraday probes are used to simultaneously measure the ion current density of a 5 kW Hall th ... Full text Cite

Current collection to long conductors with wide geometries for bare electrodynamic tether applications: A laboratory update

Conference 40th AIAA Aerospace Sciences Meeting and Exhibit · January 1, 2002 We describe chamber tests of simulated electrodynamic tethers (EDTs) of different geometries operating in a dense, high-speed plasma. The geometries tested and described here were cylindrical and flat-ribbon. Several important conclusions that can be drawn ... Full text Cite

Preliminary plume characterization of a low-power Hall thruster cluster

Conference 38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2002 In an effort to understand the technical issues related to running multiple Hall effect thrusters in close proximity to each other, testing of a cluster of four Busek BHT-200-X3 devices has begun in Chamber 6 at the Air Force Research Laboratory. Prelimina ... Full text Cite

Pressure map of a facility as a function of flow rate to study facility effects

Conference 38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2002 A neutral gas background pressure map of the Large Vacuum Test Facility (LVTF) at the University of Michigan is presented. The LVTF was mapped at a series of cold anode flow rates corresponding to P5 Hall thruster operating conditions of 1.5, 3.0, and 9.0 ... Full text Cite

An experimental investigation of the internal magnetic field topography of an operating Hall thruster

Journal Article Physics of Plasmas · January 1, 2002 Full text Cite

Plume study of a 1.35-kW SPT-100 using a ExB probe

Journal Article Journal of Spacecraft and Rockets · January 1, 2002 The ion energy distributions of Xe1+, Xe2+, and Xe3+ ions in the SPT-100 plume obtained 50 cm and 1 m from the thruster exit with an ExB probe are presented. Most of the ion species distribution functions exhibit features associated with both Maxwellian an ... Full text Cite

Correlating laser induced fluorescence and molecular beam mass spectrometry ion energy distributions

Journal Article Journal of Propulsion and Power · January 1, 2002 Full text Cite

Analysis of chamber simulations of long probes in high-speed, dense plasmas

Conference 39th Aerospace Sciences Meeting and Exhibit · December 1, 2001 We describe chamber tests of simulated electrodynamic tethers (EDTs) of different geometries operating in a dense, high-speed plasma. The geometries tested and described here were cylindrical and flat-ribbon. Several important conclusions that can be drawn ... Cite

Development of the linear gridless ion thruster

Conference 37th Joint Propulsion Conference and Exhibit · December 1, 2001 The design of the Linear Gridless Ion Thruster, or LGIT, is presented in detail. The LGIT is a hybrid thruster that combines an ionization stage similar to those normally found on gridded ion engines with the acceleration mechanism of a Hall effect thruste ... Cite

Review of the EP activities of US academia

Conference 37th Joint Propulsion Conference and Exhibit · December 1, 2001 A review of electric propulsion (EP) research activities at academic institutions throughout the United States is presented. The research presented here encompasses experimental, computational, and theoretical investigations of a wide variety of electric p ... Cite

Internal plasma potential profiles in a laboratory-model Hall thruster

Journal Article Physics of Plasmas · February 1, 2001 The Plasmadynamics and Electric Propulsion Laboratory High-speed Axial Reciprocating Probe system is used in conjunction with a floating emissive probe to measure plasma potential in the discharge chamber of the P5 Hall thruster. Plasma potential measureme ... Full text Cite

Experimental investigation of hall thrusterinteral magnetic field topography

Conference 37th Joint Propulsion Conference and Exhibit · January 1, 2001 Magnetic field measurements were made in the discharge channel of the 5-kW-class P5 laboratory-model Hall thruster to investigate what effect the Hall current has on the static, applied magnetic field topology. The P5 was operated at 1.6 kW and 3.0 kW with ... Full text Cite

Considerations on the role of the hall current in a laboratory-model thruster

Conference 37th Joint Propulsion Conference and Exhibit · January 1, 2001 Hall current magnitude and spatial distribution are presented for the plasma discharge in the University of Michigan/Air Force Research Laboratory P5 5 kW laboratory-model Hall thruster. The data are calculated from direct, probe-based measurements of the ... Full text Cite

Ground simulations of electron current to wide probes for electrodynamic tethers

Conference 37th Joint Propulsion Conference and Exhibit · January 1, 2001 We describe chamber tests of simulated electro dynamic tethers (EDTs) of different geometries operating in a dense, high-speed plasma. The geometries tested and described here were cylindrical and flat-ribbon. Several important conclusions that can be draw ... Full text Cite

Computation of the interior and near-field flow of a 2-kW class hall thruster

Conference 37th Joint Propulsion Conference and Exhibit · January 1, 2001 A time-accurate 2D axisymmetric Hybrid PIC-MCC model is used to simulate the plasma flow in the acceleration channel and near-field plume of a Hall thruster. The model is applied to the P5 Hall thruster due to known magnetic configuration and the availabil ... Full text Cite

Near- and far-field characterization of stationary plasma thruster plumes

Journal Article Journal of Spacecraft and Rockets · January 1, 2001 A comprehensive investigation of Hall thruster plume plasma ion energy distribution functions and ion charge state has been made on both flight- and laboratory-model engines. An energy analyzer, mass spectrometer, and E × B probe were used to characterize ... Full text Cite

Near-field ion energy and species measurements of a 5-kW hall thruster

Journal Article Journal of Propulsion and Power · January 1, 2001 A molecular beam mass spectrometer has been used to determine the ion composition and energy distribution of the P5 5-kW class laboratory Hall thruster. A skimmer was used to obtain a sample of the plasma 10 cm downstream of the thruster exit plane. The th ... Full text Cite

Simulating ionospheric plasma with a hollow cathode in a large vacuum chamber

Journal Article Journal of Spacecraft and Rockets · January 1, 2001 A plasma environment closely approximating the ionosphere can be generated by a hollow cathode assembly in a large vacuum chamber. This capability allows examinations of ionospheric-plasma phenomena in a controlled setting without, in most cases, relying o ... Full text Cite

Spacecraft interaction test results of the high performance hall system SPT-140

Conference 35th Intersociety Energy Conversion Engineering Conference and Exhibit · December 1, 2000 Ground rests were performed to help characterize modes of interaction between the SPT-140 Hall thruster and spacecraft components. The experiments were performed at NASA Glenn Research Center and at the University of Michigan. Measurements were made of thr ... Cite

FMT-2 discharge cathode erosion rate measurements via laser- induced fluorescence

Conference 35th Intersociety Energy Conversion Engineering Conference and Exhibit · December 1, 2000 Relative erosion-rates and impingement ion production mechanisms have been identified for the discharge cathode of a 30 cm ion engine using laser-induced fluorescence (LIF). Mo and W erosion products as well as neutral and singly ionized xenon were interro ... Cite

Status of US testing of the High Performance Hall System SPT-140 Hall thruster

Conference 38th Aerospace Sciences Meeting and Exhibit · December 1, 2000 The High Performance Hall System (HPHS) program supports the development and flight qualification of a 4.5 kW electric propulsion system that includes the SPT-140 Hall thruster. The Air Force Research Laboratory (AFRL) and International Space Technology, I ... Cite

Laser-induced fluorescence characterization of ions emitted from hollow cathodes

Journal Article IEEE Transactions on Plasma Science · December 1, 2000 Laser-induced fluorescence (LIF) was used to measure the mean and variance of the velocity distribution of xenon ions emitted from two hollow cathode assemblies operating at low power. High-energy ions detected in plume-mode and spot-mode operation are con ... Full text Cite

An investigation of internal ion number density and electron temperature profiles in a laboratory-model Hall thruster

Conference 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2000 Experiments have been conducted at the University of Michigan Plasmadynamics and Electric Propulsion Laboratory (PEPL) to investigate the acceleration and ionization mechanisms in the P5 laboratory-model Hall thruster. A cylindrical, double Langmuir probe ... Full text Cite

Spacecraft interaction test results of the high performance hall system SPT-140

Conference 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2000 Ground rests were performed to help characterize modes of interaction between the SPT-140 Hall thruster and spacecraft components. The experiments were performed at NASA Glenn Research Center and at the University of Michigan. Measurements were made of thr ... Full text Cite

Developing field emitter array cathode systems for electrodynamic tether propulsion

Conference 35th Intersociety Energy Conversion Engineering Conference and Exhibit · January 1, 2000 Field Emitter Array Cathodes (FEAC) are a new technology being developed for several potential spacecraft electron emission and charge control applications. Instead of a single hot (i.e. high powered) emitter, or a gas dependant plasma contactor, FEAC syst ... Full text Cite

Developing field emitter array cathode systems for electrodynamic tether propulsion

Conference 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2000 Field Emitter Array Cathodes (FEAC) are a new technology being developed for several potential spacecraft electron emission and charge control applications. Instead of a single hot (i.e. high powered) emitter, or a gas dependant plasma contactor, FEAC syst ... Cite

FEA cathodes (FEACs) for space based applications

Journal Article IEEE International Conference on Plasma Science · January 1, 2000 The capability of field emitter array cathodes (FEAC) for space applications as a function of materials, geometry, and space charge limitations is analyzed by FEA. The parameters equipped of FEAC is in terms of emission performance, lifetime, operational c ... Full text Cite

Very-near-field plume investigation of the anode layer thruster

Journal Article Journal of Propulsion and Power · January 1, 2000 The plasma properties of the very-near-field (10-50 mm) plume of the D55 anode layer thruster (TAL) were measured. The D55 is the 1.35-kW TAL counterpart to the SPT-100 and was made by the Central Scientific Research Institute of Machine Building of Kalini ... Full text Cite

Development of a high-speed, reciprocating electrostatic probe system for Hall thruster interrogation

Journal Article Review of Scientific Instruments · January 1, 2000 The use of electrostatic probes to measure local plasma parameters inside the discharge chamber of a Hall thruster presents significant difficulties. The high-temperature, dense plasma, and Hall current in the accelerating channel heat the probe rapidly ca ... Full text Cite

Laser-induced fluorescence characterization of ions emitted from hollow cathodes

Journal Article IEEE Transactions on Plasma Science · January 1, 2000 Laser-induced fluorescence (LIF) was used to measure the mean and variance of the velocity distribution of xenon ions emitted from two hollow cathode assemblies operating at low power. High-energy ions detected in plume-mode and spot-mode operation are con ... Full text Cite

FMT-2 discharge cathode erosion rate measurements via laser-induced fluorescence

Conference 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 2000 Relative erosion-rates and impingement ion production mechanisms have been identified for the discharge cathode of a 30 cm ion engine using laser-induced fluorescence (LIF). Mo and W erosion products as well as neutral and singly ionized xenon were interro ... Cite

Numerical thermal model of NASA solar electric propulsion technology application readiness ion thruster

Journal Article Journal of Propulsion and Power · January 1, 2000 A thermal computer model of the 30-cm NASA solar electric propulsion technology application readiness (NSTAR) xenon ion thruster has been produced using a lumped-parameter thermal nodal-network scheme. This model contains 104 nodes on the thruster and was ... Full text Cite

Optimization of Hall thruster magnetic field topography

Journal Article IEEE International Conference on Plasma Science · January 1, 2000 The improvement of the performance and component lifetime of a closed drift Hall thruster, as well as a decrease of plume divergence and plasma-spacecraft interaction is a goal of many research efforts at the University of Michigan. A three-dimensional mag ... Full text Cite

Experimental investigation of Hall thruster magnetic field topography

Journal Article IEEE International Conference on Plasma Science · January 1, 2000 Magnetic field measurements are made in the discharge channel of the Plasmadynamics and Electric Propulsion Laboratory (PEPL) 5 kW P5 Hall thruster. The P5 operating conditions were maintained throughout the experiment at a discharge voltage and current of ... Full text Cite

Plasma density measurements inside a laboratory model Hall thruster using a resonance probe diagnostic

Journal Article IEEE International Conference on Plasma Science · January 1, 2000 Plasma density measurements are made in the discharge chamber of the Plasmadynamics and Electric Propulsion Laboratory (PEPL) P5 laboratory model Hall thruster. A thruster operating condition of 300 V and 5.4 A is maintained throughout the experiment. A re ... Cite

Space based applications for FEA cathodes (FEAC)

Journal Article Materials Research Society Symposium-Proceedings · January 1, 2000 Cold cathodes such as field emitter arrays offer the potential to benefit or enable space-based applications of critical commercial, government, or military importance by providing an electron source that is low power, low cost, requires no consumables, po ... Full text Cite

Ion-energy diagnostics in the plasma exhaust plume of a Hall thruster

Journal Article Journal of Propulsion and Power · January 1, 2000 Of primary concern with the integration of Hall thrusters on conventional satellite designs is the possible damaging effect of high-energy exhaust ions impinging upon spacecraft surfaces. This paper reports on measurements of plasma ion-energy distribution ... Full text Cite

Spectroscopic characterization of FMT-2 discharge ionization processes

Journal Article IEEE International Conference on Plasma Science · January 1, 2000 Discharge cathode erosion, a major failure mechanism for ion engines, is fundamentally interconnected with ionization processes. Three-component laser induced fluorescence (LIF) and emission spectroscopy measurements downstream of the FMT-2 ion engine char ... Cite

Mass spectral measurements in the plume of an SPT-100 Hall thruster

Journal Article Journal of Propulsion and Power · January 1, 2000 Knowledge of the ion species emitted by the SPT-100 Hall thruster provides considerable insight to basic thruster performance. To gain detailed information concerning the composition of the plume plasma, a unique molecular beam mass spectrometer was constr ... Full text Cite

Performance of field emission cathodes in xenon environments

Conference IEEE International Conference on Plasma Science · December 1, 1999 Field emission (FE) cathodes are currently being considered to supply electrons in electric propulsion systems for propellant ionization and ion beam neutralization. Hollow cathodes with thermionic electron emitters typically used with Hall and ion thruste ... Cite

Density and spectral measurements using a 34 GHz interferometry system

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 Interferometry was used to investigate the impact of the plasma plume of the University of Michigan P5 thruster on microwave signals. Measurements were made at 34 GHz using a newly built Ka-band interferometer and also at 17 GHz similar to other measuremen ... Cite

Laser induced fluorescence characterization of ions emitted from hollow cathodes

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 Laser induced fluorescence (LIF) was used to measure the mean and variance of the velocity distribution of xenon ions emitted from two hollow cathode assemblies operating at low power. High-energy ions detected in plumemode and spot-mode operation are cons ... Cite

Resonance-probe measurements of plasma densities in electric-propulsion plumes

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 We are developing a resonance-probe plasma diagnostic that uses a microwave network analyzer for use in electric-propulsion research. To show the feasibility of our resonance-probe implementation, we have measured plasma densities in the plume of the 5-kW- ... Full text Cite

Plume study of a 1.35 kw spt-100 using an exb probe

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 The ion energy distribution of each ion species in the SPT-100 plume was obtained at various angles off thruster axis at 1 m and 50 cm from the thruster exit using an ExB probe. Each peak of the measured ExB probe traces was fitted using a model based on t ... Cite

Near-field ion energy and species measurements of a 5 kw laboratory hall thruster

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 The Plasmadynamics and Electric Propulsion Laboratory (PEPL) has used its Molecular Beam Mass Spectrometer (MBMS) to determine the ion energy distribution of the P5 5 kW laboratory Hall thruster. A skimmer was used to obtain a sample of the plasma in the n ... Cite

Low-current hollow cathode evaluation

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 An experimental investigation of the operating characteristics of 3.2 mm diameter orificed hollow cathodes was conducted to examine low-current and low flow rate operation. Cathode power was minimized with low orifice aspect ratio and the use of an enclose ... Cite

The far-field plasma environment of a hollow cathode assembly

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 Using a hollow cathode assembly (HCA) in a large vacuum chamber, such as the University of Michigan’s Large Vacuum Test Facility (LVTF), provides the capability of generating a plasma environment that closely approximates that of the ionosphere. This capab ... Full text Cite

Laser induced fluorescence measurement of ion velocities in the plume of a hall effect thruster

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 Laser induced fluorescence (LIF) was used to measure the mean and variance of the velocity distribution of xenon ions in the plume of the P5 Hall thruster. The data indicate an acceleration region extending several centimeters downstream of the exit plane. ... Cite

Hall thruster discharge chamber plasma characterization using a high-speed axial reciprocating electrostatic probe

Conference 35th Joint Propulsion Conference and Exhibit · January 1, 1999 Electron temperature, number density, plasma potential and floating potential were measured in the interior and very-near-field region of the P5 Hall thruster using the newly developed High-speed Axial Reciprocating Probe (HARP) positioning system. The HAR ... Full text Cite

Identifying charge-exchange collision products within the ion-energy distribution of electrostatically accelerated olasmas

Journal Article Physics of Plasmas · January 1, 1999 When used in flowing electrostatically accelerated plasmas, electrostatic energy analyzers, such as Retarding Potential Analyzers (RPA's) or Cylindrical Mirror Analyzers (CMA's), occasionally yield data which seem implausible: for a known applied plasma ac ... Full text Cite

Modeling of Stationary Plasma Thruster-100 Thruster Plumes and Implications for Satellite Design

Journal Article Journal of Propulsion and Power · January 1, 1999 A computational model of a stationary plasma thruster (SPT) has been developed using a quasineutral particle-in-cell/direct simulation Monte Carlo (PIC-DSMC) model. This model is based on theoretical work showing that the plume consists of a quasineutral p ... Full text Cite

Exhaust beam profiles of hall thrusters

Journal Article Transactions of the Japan Society for Aeronautical and Space Sciences · February 1, 1998 The exhaust plume profiles of Hall thrusters are measured with Langmuir probes and beam-ion collectors. The results show that 95% of total beam-ion current exists within the angle of 70 degrees off the thruster centerline. The divergent angle decreased wit ... Cite

Thermographic investigation of 3.2 mm diameter orificed hollow cathodes

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 In an effort to support the needs of emerging low-power electric propulsion systems, efficient, low-current hollow cathodes are being developed at the NASA Lewis Research Center. A thermal model of the hollow cathode is currently under development, and a l ... Full text Cite

Field emission array cathodes for electric propulsion systems

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 Compatibility issues associated with using field emission array (FEA) cathodes as the electron sources for Hall and ion thrusters were explored and FEA cathode performance is discussed. The cathode environment was characterized using a Faraday probe and NP ... Full text Cite

Performance characteristics of a 5 kW laboratory hall thruster

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 The University of Michigan and United States Air Force Research Laboratory have jointly developed a 5 kW class Hall effect thruster. This thruster was developed to investigate, with a variety of diagnostics, a thruster similar to that specified by IHPRPT g ... Full text Cite

Parametric investigation of orifice aspect-ratio on low current hollow cathode power consumption

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 As part of an effort to develop efficient hollow cathodes for the International Space Station and low power electric propulsion systems, the effects of orifice length-to-diameter aspect-ratio on the performance of 0.5 to 2 A hollow cathodes were examined t ... Full text Cite

Near-field investigation of ions emitted from a hollow cathode assembly operating at low-power

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 RPA and Langmuir probe measurements were made in the near-field plume on the axis of a hollow cathode assembly (HCA). High-energy ions were detected at low-powers consistent with the detection of such ions at high powers in previous investigations. The abs ... Cite

Propellant lonization and mass spectral measurements in the plume of an SPT-100

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 Knowledge of the ion species emitted by the SPT-100 Hall thruster provides considerable insight to the basic thruster performance. In order to gain detailed information concerning the composition of the plume plasma a custom molecular beam mass spectromete ... Cite

Ion energy diagnostics in the plume of an SPT-100 from thrust axis to backflow region

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 Of primary concern with the integration of Hall thrusters on conventional satellite designs is the possible damaging effect of high-energy exhaust ions impinging upon spacecraft surfaces. This paper reports on measurements of plasma ion energy distribution ... Full text Cite

Electromagnetic wave scattering experiments in hall thruster plasma plumes

Conference 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit · January 1, 1998 We report on electromagnetic wave (EM) scattering experiments using a 17 GHz signal propagated through an electric propulsion Hall thruster plume at different radial and axial distances. The goals of the experiments were to evaluate the spectral modificati ... Full text Cite

Microwave plume measurements of a closed drift hall thruster

Journal Article Journal of Propulsion and Power · January 1, 1998 The plasma plume from a closed drift hall thruster has been characterized using a 17-GHz microwave diagnostic system. Electron number density profiles are obtained throughout the thruster plume via differential phase measurements. A functional model of pla ... Full text Cite

Field emission array cathode performance in electric propulsion system environments

Conference IEEE International Conference on Plasma Science · January 1, 1998 The recent drive towards utilizing electric propulsion systems for micro spacecraft warrants the development of efficient, low power and low propellant consumption cathodes. Because of the lower limits on size, power and propellant consumption of hollow ca ... Cite

A Hall probe diagnostic for low density plasma accelerators

Journal Article Review of Scientific Instruments · January 1, 1998 A Hall probe diagnostic was developed for use with plasma thrusters. The Hall generators were mounted at the end of a stainless steel tube heat exchanger. Ceramic cement and a Pyrex tube were used as radiation and particle flux shields, respectively. A the ... Full text Cite

Transport-property measurements in the plume of an SPT-100 hall thruster

Journal Article Journal of Propulsion and Power · January 1, 1998 To understand the interaction between the SPT-100 thruster and the spacecraft, accurate knowledge of exhaust plume properties must be obtained. This investigation utilized a suite of interrelated diagnostic probes in an effort to provide detailed knowledge ... Full text Cite

The effect of an auxiliary discharge on anode sheath potentials in a transverse discharge

Journal Article Journal of Applied Physics · April 15, 1997 A novel scheme that employs the use of an auxiliary discharge has been shown to reduce markedly anode sheath potentials in a transverse discharge. An 8.8 A low-pressure argon discharge in the presence of a transverse magnetic field was used as the plasma s ... Full text Cite

Flexible microwave system to measure the electron number density and quantify the communications impact of electric thruster plasma plumes

Journal Article Review of Scientific Instruments · February 1, 1997 A microwave interferometer has been implemented that can map the local electron density in two directions, and determine chamber effects such as resonances and multipath through the use of a network analyzer. The same system can be used for communications ... Full text Cite

A molcular beam mass spectrometer for hall thruster plume studies: Preliminary data

Conference 33rd Joint Propulsion Conference and Exhibit · January 1, 1997 The motivation behind the construction of a Molecular Beam Mass Spectrometer (MBMS) for transport property measurements in Hall thruster plumes is presented. This system utilizes a set of orifice plates to skim off a small beam of plasma from the plume of ... Cite

Impact of anode layer thruster plumes on satellite communications

Conference 33rd Joint Propulsion Conference and Exhibit · January 1, 1997 Microwave interferometry was used to investigate the impact of the plume of a D-55 anode layer thruster on satellite communications. A 17 GHz microwave signal was transmitted through the plume in order to measure phase shift and signal attenuation at vario ... Cite

Very near-field plume investigation of the D55

Conference 33rd Joint Propulsion Conference and Exhibit · January 1, 1997 The plasma properties of the very near-field (10 to 50 mm) plume of the D55 anode layer thruster (TAL) were measured as part of an effort lead by NumerEx of Albuquerque, NM to model the processes within TALs. The D55 is the 1.35 kW TAL counterpart to the S ... Cite

Gridded retarding pressure sensor for ion and neutral particle analysis in flowing plasmas

Journal Article Review of Scientific Instruments · January 1, 1997 Although classical electrostatic plasma probes can provide detailed information regarding electrons and ions, these devices rely on charge-carrying particles both for energy filtering and for detection. Neutral particles are transparent to such diagnostics ... Full text Cite

Approximating collisional freestream attenuation at transitional knudsen numbers

Journal Article AIAA Journal · January 1, 1997 Full text Cite

Ionic and neutral particle transport property measurements in the plume of an SPT-100

Conference 32nd Joint Propulsion Conference and Exhibit · January 1, 1996 In order to understand the interaction between the SPT-100 thruster and the spacecraft accurate knowledge of exhaust plume properties must be obtained. This investigation utilized a suite of inter-related diagnostic probes in an effort to provide detailed ... Full text Cite

RF signal impact study of an SPT

Conference 32nd Joint Propulsion Conference and Exhibit · January 1, 1996 Stationary plasma thrusters (SPTs) are currently being tested and considered for use aboard next generation spacecraft for North-South station keeping, repositioning, and orbit transfer due to their high thrust efficiency and nearly optimal specific impuls ... Full text Cite

The D-100 performance and plume characterization on krypton

Conference 32nd Joint Propulsion Conference and Exhibit · January 1, 1996 The performance of a D-100 thruster with anode layer, designed to operate on xenon at a nominal operating power of 4.5 kW, was investigated during operation on krypton. This evaluation was preliminary to a more thorough investigation of D-100 operation on ... Full text Cite

Very-near-field plume study of a 1.35 kw SPT-100

Conference 32nd Joint Propulsion Conference and Exhibit · January 1, 1996 Ion current density and electron number density profiles were measured in the very-nearfield plume of a 1.35 kW stationary plasma thruster (SPT-100) loaned from Space Systems/Loraland Fakel Enterprises. In order to take these measurements without significa ... Full text Cite

Plume characterization of the SPT-100

Conference 32nd Joint Propulsion Conference and Exhibit · January 1, 1996 The following provides a first year summary of a research program sponsored by the AFOSR to characterize the SPT-100 for far-field plume plasma and transport properties as well as thruster operation impact to electromagnetic signals used for communication, ... Full text Cite

A gridded retarding pressure sensor for ion and neutral particle analysis in flowing plasmas

Conference 32nd Joint Propulsion Conference and Exhibit · January 1, 1996 Although classical electrostatic plasma probes can provide detailed information regarding electrons and ions, these devices rely on charge-carrying particles both for energy filtering and detection Neutral particles are transparent to such diagnostics. In ... Full text Cite

An investigation into the role that a transverse magnetic field plays in the formation of large anode sheath potentials

Journal Article Physics of Plasmas · January 1, 1996 A 9.25 A low-pressure (45-55 mTorr) hollow cathode arc discharge has been used to simulate plasma processes that occur at the anode of magnetoplasmadynamic accelerators used for space propulsion applications. The interest in the near-anode region is relate ... Full text Cite

Near- and far-field plume studies of a one-kilowatt arcjet

Journal Article Journal of Propulsion and Power · January 1, 1996 To support studies of transport in arcjet plumes, axial and radial profiles of electron temperature, electron number density, stagnation pressure, and flowfield were obtained over an extensive volume of the plume of a 1-kW arcjet operating on hydrogen. All ... Full text Cite

Effect of electron re-population of the near-anode region on the measured anode fall voltage of a transverse discharge

Conference IEEE International Conference on Plasma Science · January 1, 1996 In an attempt to reduce the large anode fall voltages associated with transverse discharges, the use of a secondary discharge to introduce or generate more electrons in the near-anode region is investigated. Changes in near-anode plasma properties are meas ... Cite

Ion acoustic wave characterization in a moving plasma to find bulk flow velocity

Conference IEEE International Conference on Plasma Science · January 1, 1996 The bulk flow velocity is an important parameter in characterizing moving plasmas, such as electric propulsion plasma plumes. The bulk flow velocity can be found directly through interpretation of the propagating characteristics of an ion acoustic wave. Th ... Cite

Preliminary pulsed MPD thruster performance

Conference 31st Joint Propulsion Conference and Exhibit · January 1, 1995 A thrust stand was modified, and a primary calibration technique was developed to evaluate the performance of applied-field pulsed magnetoplasmadynamic thrusters (MPDTs) for 10 kW class solar electric orbit transfer vehicle (SEOTV) missions. The NASA Lewis ... Full text Cite

Determining thruster plume impingement forces and free stream dynamic pressure from impact pressure measurements at transitional Knudsen numbers

Conference 31st Joint Propulsion Conference and Exhibit · January 1, 1995 This paper presents a comprehensive theoretical numerical, and experimental investigation of the phenomena encountered when analyzing exo-atmospheric plume impingement loads. An analytic model combined with Monte Carlo simulations is used to study the rela ... Cite

Microwave plume measurements of an SPT-100 using xenon and a laboratory model SPT using krypton

Conference 31st Joint Propulsion Conference and Exhibit · January 1, 1995 The plasma plumes from two stationary plasma thrusters (SPTs), a flight qualified SPT-100 using xenon and a laboratory model SIT using krypton, have been measured using microwave diagnostic systems capable of differential phase, differential amplitude, and ... Full text Cite

An investigation of stationary plasma thruster performance with krypton propellant

Conference 31st Joint Propulsion Conference and Exhibit · January 1, 1995 The objective of this research was to characterize the performance of a 1.35 kW stationary plasma thruster (SPT) with krypton as the propellant. Research carried out by Bugrova et al. [l] demonstrated that SPT performance on krypton is comparable to that o ... Cite

Nonintrusive Electron Number Density Measurements in the Plume of a 1 kW Arcjet Using a Modern Microwave Interferometer

Journal Article IEEE Transactions on Plasma Science · January 1, 1995 Reported here is the use of a microwave interferometric technique for making nonintrusive measurements of plasma electron number density in the plume of a space electric propulsion thruster. The technique is capable of providing good sensitivity and accura ... Full text Cite

The adverse effect of perpendicular ion drift flow on cylindrical triple probe electron temperature measurements

Journal Article Review of Scientific Instruments · December 1, 1994 The cylindrical triple probe method is an attractive technique for measuring electron temperatures (Te) and electron number densities (ne) in a variety of plasmas sources. In practice, however, the cylindrical triple probe can be sensitive to sources of er ... Full text Cite

Anode power deposition in an applied-field segmented anode mpd thruster

Journal Article Journal of Propulsion and Power · January 1, 1994 Anode heat flux measurements of a water-cooled segmented anode applied-field MPD thruster were made to investigate anode heat transfer phenomena. Pure argon and argon-hydrogen mixtures were used as propellants for a variety of thruster currents, propellant ... Full text Cite

Use of permanent magnets to reduce anode losses in mpd thrusters

Journal Article Journal of Propulsion and Power · January 1, 1994 Results from previous studies indicate that the anode fall, the principal source of anode heating in MPD thrusters, increases monotonically with the electron Hall parameter calculated from electron temperature, number density, and magnetic field data obtai ... Full text Cite

Anode power deposition in magnetoplasmadynamic thrusters

Journal Article Journal of Propulsion and Power · January 1, 1993 Results of anode heat-flux and anode fall measurements from a multimegawatt self-field quasisteady magnetoplasmadynamic (MPD) thruster are presented. Measurements were obtained with argon and helium propellants for a variety of currents and mass flow rates ... Full text Cite

Anode power deposition in a MPD thruster with a magnetically annulled hall parameter anode

Conference AIAA/ASME/SAE/ASEE 28th Joint Propulsion Conference and Exhibit, 1992 · January 1, 1992 Results from previous studies indicate that the anode fall increases monotonically with the electron Hall parameter calculated from electron temperature, number density, and magnetic field data obtained near the anode. In an attempt to reduce the anode fal ... Full text Cite

Anode power deposition in quasisteady magnetoplasmadynamic thrusters

Journal Article Journal of Propulsion and Power · January 1, 1992 Spatially resolved anode heat flux measurements of a pulsed quasisteady magnetoplasmadynamic (MPD) thruster have been made by embedding thermocouples to the inner surface of a hollowed anode. Results obtained using argon propellant at mass flow rates of 4 ... Full text Cite

Anode power deposition in quasi-steady MPD thrusters

Conference AlAA/DGLR/JSASS 21st International Electric Propulsion Conference, 1990 · January 1, 1990 Spatially resolved anode heat flux measurements of a pulsed quasi-steady MPD thruster have been made by embedding thermocouples to the inner surface of a hollowed anode. Results obtained using argon propellant at mass flow rates of 4 and 16 g/s with the th ... Cite

INVESTIGATION OF BEAMED-ENERGY ERH THRUSTER PERFORMANCE.

Conference AIAA Paper · December 1, 1986 The objective of this study was to determine the performance of an External Radiation Heated (ERH) Thruster. In this thruster, high intensity laser energy is focused to ignite either a Laser Supported Combustion (LSC) wave or a Laser Supported Detonation ( ... Cite