Experimental Study of the Neutralization Process in Field- Emission Electric Propulsion (original) (raw)

Results of an experimental test campaign dealing with the neutralization on FEEP technology are reported together with simulations of the thermionic neutralizer chosen for the MICROSCOPE and LISA-Pathfinder missions. Stabilization of the floating potential is obtained instantaneously predicting a moderate charging of the spacecraft in a range of a hundred of Volts. Ion induced secondary electron emission negligible influence on neutralization process is demonstrated. Plasma parameters inside the vacuum chamber are roughly extrapolated from neutralizer performances and correlated with thruster propellant.

Neutraliser for FEEPs: review on the development status

Since year 2005 a new neutraliser concept has been developed, to be used for neutralisation of the positive charges in the beam of FEEP thrusters. The unit design is now mature for the flight phases of both the European LISA PF and Microscope programs. The device is based on a small light and low power consumption Barium impregnated cathode operating without the need of Xenon gas. The neutraliser works in a biased diode configuration allowing the extraction of electrons and their acceleration to be independent processes separately controlled by the Power Supply Unit. The qualification activities have been successfully completed on both the two mentioned programs. Lifetime tests are presently concluded under the MICROSCOPE program (1000h) and ongoing under the LISA PF one (6000h expected, more than 3500h, presently achieved). During ground tests these devices have demonstrated the ability to emit the specified current levels asking for a negative bias of few tens of Volts. Then, it i...

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