Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articlePlasma 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 ...
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Journal articleAerospace · 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 ...
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Journal articleJournal 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 ...
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Journal articlePlasma 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. ...
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Journal articlePhysics 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 ...
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Journal articlePhysics 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 ...
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Journal articlePhysics 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 ...
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Journal articleJournal 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, ...
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Journal articleJournal 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 ...
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Journal articleThe 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 ...
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Journal articleJournal 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 ...
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Journal articleIEEE 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 ...
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Journal articlePhysics 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 ...
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Journal articleJournal 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 ...
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Journal articleReview 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 ...
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Journal articleJournal 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 ...
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Journal articleReview 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 ...
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Journal articlePlasma 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 exp ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articlePlasma 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 ...
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Journal articleIEEE 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 ...
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Journal articlePlasma 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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'[ ...
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Journal articleReview 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 ...
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Journal articlePhysics 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 ...
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Journal articleReview 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 ...
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Journal articleReview 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 ...
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Journal articleReview 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 ...
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Journal articlePlasma 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleReview 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articlePhysics 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articlePhysics 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 ...
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Journal articlePhysics 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 ...
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Journal articleReview 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 ...
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Journal articleReview 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleSpace 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 imag ...
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Journal articlePhysics 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 ...
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Journal articleIEEE 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 ...
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Journal articleReview 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) ...
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Journal articleJournal 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 ...
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Journal articleApplied 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleIEEE 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 ...
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Journal articleIEEE 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 ...
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Journal articleJournal 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 a ...
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Journal articlePhysics 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleIEEE 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 ...
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Journal articleIEEE 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 ...
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Journal articleJournal 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 ...
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Journal articleReview 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 ...
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Journal articleIEEE 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 ...
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Journal articleJournal 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 ...
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Journal articleIEEE 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 ...
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Journal articleIEEE 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 ...
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Journal articleIEEE 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 ...
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Journal articleMaterials 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 ...
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Journal articleJournal 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 ...
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Journal articleIEEE 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 ...
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Journal articleJournal 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 ...
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Journal articlePhysics 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 ...
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Journal articleJournal 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 ...
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Journal articleTransactions 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 ...
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Journal articleJournal 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 ...
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Journal articleReview 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleReview 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 ...
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Journal articleReview 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 ...
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Journal articlePhysics 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 ...
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Journal articleJournal 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 ...
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Journal articleIEEE 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 ...
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Journal articleReview 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 sens ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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Journal articleJournal 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 ...
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