Development of Miniature Microwave Discharge Neutralizer for Miniature Ion Thruster

Abstract

A miniature microwave discharge neutralizer has been developed in order to develop the miniature ion engine system. Extracted electron currents from the microwave discharge neutralizer are measured for two neutralizers, cylindrical discharge chamber with monopole antenna and the same discharge chamber as miniature microwave discharge ion thruster developed at Kyushu University for two orifice diameters. The former shows that the extracted electron current is 14 mA at incident microwave power of 4 W, 6 mA at incident microwave power of 2 W at mass flow rate of 0.005 mg/s. This small extracted current would be due to the large loss on the discharge chamber wall. On the other hand, the best extracted electron current of the latter, is 11 mA at mass flow rate of 0.005 mg/s and incident microwave power of 4 W, by optimizing the orifice diameter or position of the orifice plate. From the poor performance at incident microwave power of 2 W, the plasma- microwave coupling is worse than that of the former.