Background Pressure Effects on Ion Velocity Distribution Within a Medium-Power Hall Thruster

5 torr). In addition to varying the background pressure, the radial magnetic field of the thruster was varied (by a factor of 2) between low- and high-strength configurations. The low- strength configuration produced large-magnitude anode current oscillations, whereas the high-strength configuration produced small current oscillations. Ion axial velocity distribution function peaks were used to approximate ion energy and, in turn, axial electric field strength. Acceleration profiles of the tested thruster operatingconditionswerecompared.Highbackgroundpressureoperationwasobservedtoshifttheionacceleration regionupstreaminthedischargechannel. Thewidthofthevelocitydistributionscorrelatedstrongly tothemagnetic field strength. The high magnetic field strength configuration produced narrow velocity distribution functions, whereas the low magnetic field strength configuration led to a broad velocity distribution.