Development of small-scale microwave discharge ion thruster

摘要

Study of a small-scale ion engine (diameter of 2.5 cm, input microwave power up to 25 W) utilizing microwave-discharged plasma for space propulsion is reported. The ion extraction tests are conducted under several conditions such as the input microwave power range of 15-25 W, the Ar gas (as propellant) flow rate range of 1.5-3.5 sccm, and two types of antenna shape (L-type or disk antenna). In the tests, ion beam currents and distributions of ion beam current density are measured. As a result, maximum ion current of 8.2 mA is attained at input power of 25 W and Ar gas flow rate of 3.15 sccm with the L-type antenna. Ion production cost and propellant utilization efficiency are estimated from the ion current measurements to examine performances of the thruster. The plasma parameter measurements of electron temperature and density in the plasma source are also carried out. (C) 2004 Elsevier Ltd. All rights reserved.