Krypton ion thruster performance

Abstract

Preliminary data were obtained from a 30 cm ion thruster operating on krypton propellant over the input power range of 0.4-5.5 kW. The data are presented, and compared and contrasted to those obtained with xenon propellant over the same input power envelope. Typical krypton thruster efficiency was 70 percent at a specific impulse of approximately 5000 s, with a maximum demonstrated thrust-to-power ratio of approximately 42 mN/kW at 2090 s specific impulse and 1580 watts input power. Critical thruster performance and component lifetime issues were evaluated. Order-of-magnitude power throttling was demonstrated using a simplified power-throttling strategy. parative assessment of overall thruster performance and lifetime expectations to that obtained with xenon propellant. Apparatus and Procedure A 30 cm diameter laboratory-model ion thruster was used to conduct the performance tests. The thruster, originally developed and optimized for xenon, 7 incorporated a segmented-anode geometry consisting of 3 stainless steel segments and has an exterior chamber of 0.76 mm thick cold rolled steel. The thruster uses a 'reverse-injection' propellant system for the main flow to reduce the neutral loss rate associated with the use of krypton propellant. A low-mass magnetic circuit design was employed using samarium-cobalt permanent magnets arranged to form a ring-cusp field boundary. 6's Conventional hollow cathodes, consisting of a molybdenumrhenium alloy tube and a thoriated tungsten orifice plate were employed in the discharge chamber and in the neutralizer. The orifice diameters of the discharge and the neutralizer cathodes were 1.52 mm and 0.51 mm, respectively. The cathodes utilize porous tungsten inserts impregnated with a low work function compound as the

Luminescence Measurements of the Kr+/Kr2+ + Kr Collision Systems

“…The generation of high energy ions can result in erosion of the walls of acceleration channels. [6][7][8] The divergence of the ion beam after passing through the exit plane is generally e -+ Kr  Kr * + e - (1)  Kr n+* + (n + 1)e - (2) e -+ Kr +  Kr n+* + ne -…”

“…e -+ Kr m  Kr * + e - (4)  Kr n+* + (n + 1)e - (5) Kr + + Kr  Kr * + Kr +* (6) Kr 2+ + Kr  Kr * + Kr 2+* (7)…”

Ion thruster development at NASA Lewis Research Center

“…Thirty and fifty centimeter diameter thrusters with dished iota optics satisfy most requirements in the 5 kW to 25 kW power range. Xenon, krypton, and argon thrusters provide thrust efficiencies of about 70% at specific impulses of 3000 s, 5000 s, and 7500 s, respectively ( Patterson andWilliams 1992 andPatterson andRawlin 1988). In all power ranges the major efforts are directed towards develophkg long-life, lightweight thrusters as well as efficient, light-weight power processors.…”