Vacuum rated flow controllers for inert gas ion enginesElectrical propulsion systems which use a gas as a propellant require a gas flowmeter/controller which is capable of operating in a vacuum environment. The presently available instruments in the required flow ranges are designed and calibrated for use at ambient pressure. These instruments operate by heating a small diameter tube through which the gas is flowing and then sensing the change in temperature along the length of the tube. This temperature change is a function of the flow rate and the gas heat capacity. When installed in a vacuum, the change in the external thermal characteristics cause the tube to overheat and the temperature sensors are then operating outside their calibrated range. In addition, the variation in heat capacity with temperature limit the accuracy obtainable. These problems and the work in progress to solve them are discussed.
Document ID
19870053862
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Pless, L. C. (California Institute of Technology Jet Propulsion Laboratory, Pasadena, United States)