Analysis of Xenon Flow Calibration Techniques for Electric Thruster Testing

In assessing the performance characteristics of Hall-effect thrusters (RETs) and ion engines, it is important to have an accurate estimate of the propellant flow rate to the engine. The difficulty lies in accurately measuring the very low flow rates, below 1 mg/s of xenon gas. Most test facilities use commercial calibration-certified mass flow controllers and meters. However, these flow meters drift over time from their calibration. Recalibration is typically an expensive and time consuming task which can only he performed at a few select locations; therefore it is desirable for an in-house calibration verification system to be available to detect calibration drift. Here we examine the theory %of constant-volume calibration, and propose a cost effective constant-volume flow rate verification apparatus. Performed in collaboration with ERC, Inc., Edwards AFB, CA.