CHARACTERISTICS OF THE T-220HT HALL -EFFECT THRUSTER

In recent tests the plume current density profile, plume ion energy, and radiated EMI were characterized for Pratt & Whitney’s T -220HT Hall Effect thruster. The T-220HT is a high pow er (6 -20 kW) thruster designed for maximum peak thrust. Tests covered a power range from 8 -10 kW and discharge voltages of 300 and 600 V. Plume measurements at Air Force Research Laboratory (AFRL) facilities demonstrated plume widths narrower than typical Hall thrusters. Half angles containing 90% of the integrated plume flux were in the range of 27 -29 °. Radiated electromagnetic emissions were measured over a frequency range from 200 MHz to 60 GHz at The Aerospace Corporation. For discharge voltages at or below 300 V, EMI was below MIL -STD 461E limits except at a single peak below 1.4 GHz, where the limit was exceeded by only about 5 dB. Increasing the discharge voltage to 600 V noticeably increased emissions in this frequency range, but these were still generally below MIL -STD 461E. Plume ion energy spectra were also characterized at The Aerospace Corporation’s facility. An RPA (Retarding Potential Analyzer) was mounted at a downstream distance of 1 meter and was varied in position from 20 ° to 100 ° fro m the thruster centerline. Measurements generally confirmed the plume profile data taken at AFRL. Energy spectra confirm that the flux at high angles is dominated by low energy charge exchange ions.