Experimental Characterization of a Micro-Hall Thruster

Theoperation andperformance of amicro-Hall thruster are characterized.The thruster is coaxial in design,with a 0.5 mm channel width and 4 mm outer diameter. The magnetic circuit includes a samarium cobalt permanent magnet generating approximately 0.7 T at the exit plane and 1 T inside the channel. Operation with a commercial hollow cathode neutralizer is achieved in the 10–40 W power range with an anode flow rate of 0:12–0:20 mg=s of xenon. The measured thrust is in the range of 0.6–1.6 mN for an anode flow rate of 0:17–0:20 mg=s and an applied voltage of 110–275 V. Anode thrust efficiency and specific impulse are in the range of 10–15 % and 300–850 s, respectively, for the same conditions. Relatively broad ion energy distributions and large beam divergence are observed from an analysis of the plume using a retarding potential analyzer and ion current probe. The discharge exhibits the characteristic Hall thruster “breathing mode ” instability in the 35–70 kHz frequency range. Nomenclature Ei = ion energy e = elementary electric charge F = thrust f = breathing mode frequency g0 = universal gravitation constant Id = discharge current Isp = anode specific impulse Ji = total ion current measured in the plume ji = angle-dependent ion current L = characteristic size of discharge mi = ion mass _m = anode mass flow rate Te = electron temperature Ud = discharge voltage vi = ion velocity vn = neutral velocity = anode thrust efficiency c = cold probe floating potential e = emissive probe floating potential p = plasma potential I.