Preliminary thrust characterization of the T-Series hollow cathode thrusters for all-electric spacecraft

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Description/Abstract

This paper characterizes thrust performance of a T5 hollow cathode and a variant of the T6 hollow cathode modified for improved operational characteristics. Both forms of device display impressive propulsive performance and bring to light their potential for application as microthrusters. The T5 hollow cathode is shown to work in an almost purely electrothermal heating mode generating specific impulse as high as 427s with argon while operating below 100W. The acceleration mechanism is shown to be almost entirely electrothermal. The variant on the T6 cathode is able to produce specific impulse of over 1050s with xenon and argon; however the dominant acceleration mechanism low flow rates is shown to be almost entirely electromagnetic effectively constituting a low power, low flow magneto-plasma-dynamic thruster. The T6 cathode displayed very low discharge voltages ~12V and stable operation while carrying currents as high as 30-Amps on flow rates of less than 0.1mgs-1 down to 0.04mgs-1 with xenon. This investigation highlights the importance of electrode geometry in hollow cathode thruster design and indeed in all other applications of hollow cathode where flow rates should be minimized.