Measurement of xenon viscosity as a function of low temperature and pressure

Stanley P. GrisnikNational Aeronautics and Space AdministrationLewis Research CenterCleveland, Ohio 44135AbstractThe measurement of xenon gas viscosity at lowtemperatures (175 to 298 K) and low pressures (350 to760 torr) has been performed in support of Hall Thrustertesting at NASA Lewis Research Center. Themeasurements were taken using the capillary flowtechnique. Viscosity measurements were repeatable towithin 3 percent. The results in this paper are in agreementwith data from Hanley and Childs and suggest that thedata from Clarke and Smith is approximately 2 percentlow. There are no noticeable pressure effects on xenonabsolute viscosity for the pressure range from 350 to760 torr.IntroductionAn interest in Russian electric propulsion technologies,specifically "Hall effect" thrusters, has increased due totheir potential to increase the performance of Westernspacecraft. Testing of these thrusters has been performedat NASA Lewis Research Center, to identify plumeproperties, performance limits, and component lifelimitations. 1 Of interest is the Russian "thermal throttle,"a capillary tube that uses resistive heating to vary theviscosity and density of the gas flowing through it andtherefore throttle the mass flowrate. The thermal throttleoperates at propellant pressures of 200 to 400 torr, andtemperatures as low as -90 °C during cold soak testing.Difficulties with thermal throttle operation at the lowtemperatures and pressures seen in the NASA Lewistesting has prompted the need for xenon viscosity data.During the course of this work, limited sources of xenonviscosity data were identified.