Dynamic electromagnetic field measurements of clustered Hall thrusters
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 performed. Several different locations were mapped and all three components of the magnetic field were recorded. A Helmholtz coil is used for high frequency calibration of the B-dot probe while a commercial Gaussmeter is used for DC magnetic field measurements and calibrations. These experiments show the electromagnets' coils do indeed experience inductive behavior at the higher frequencies but that the magnetic performance agrees well with theory. Voltage signals from the various current and magnetic field probes are processed into frequency space to visualize signal power spectrums. Several Bode plots are also constructed using the excitation current as the input of transfer functions representing the magnetic field frequency response to chirp-type excitation.
