Recommended Practice for Flow Control and Measurement in Electric Propulsion Testing

Abstract

Accurate control and measurement of propellant flow to a thruster is one of the most basic and fundamental requirements for operation of electric propulsion systems, whether they be in the laboratory or on flight spacecraft. Hence, it is important for the electric propulsion community to have a common understanding of typical methods for flow control and measurement. This paper addresses the topic of propellant flow primarily for the gaseous propellant systems that have dominated laboratory research and flight application over the last few decades, although other types of systems are also briefly discussed. Although most flight systems have employed a type of pressure-fed flow restrictor for flow control, both thermal-based and pressure-based mass flow controllers are routinely used in laboratories. Fundamentals and theory of operation of these types of controllers are presented, along with sources of uncertainty associated with their use. Methods of calibration and recommendations for calibration processes are presented. Finally, details of uncertainty calculations are presented for some common calibration methods and for the linear fits to calibration data that are commonly used.

Ion thrusters for electric propulsion: Scientific issues developing a niche technology into a game changer

“…Already today, there are a number of publications dealing with this subject and defining useful practices for a number of procedures such as measuring thrusts, measuring pressures, calculating pumping speeds, flow control, and various types of diagnostics. [268][269][270][271][272][273][274]…”

Impact of Propellant Species on Hall Effect Thruster Electrical Facility Effects

“…All experiments detailed in this work were performed using the Aerojet Rocketdyne T-40 HEToriginally developed by Space Power, Inc., in collaboration with the Keldysh Research Center and Matra Marconi Space [36]. The T-40 HET is a laboratory-model HETwith a design operational power range of 50-300 W [34,36].…”

“…All experiments detailed in this work were performed using the Aerojet Rocketdyne T-40 HEToriginally developed by Space Power, Inc., in collaboration with the Keldysh Research Center and Matra Marconi Space [36]. The T-40 HET is a laboratory-model HETwith a design operational power range of 50-300 W [34,36]. To address the loss mechanisms relevant for low-power HET operation, the T-40 HET leverages design heritage from the Aerojet Rocketdyne 3.4 kW T-140 HET as well as a patented magnetic circuit design [36].…”

“…The T-40 HET is a laboratory-model HETwith a design operational power range of 50-300 W [34,36]. To address the loss mechanisms relevant for low-power HET operation, the T-40 HET leverages design heritage from the Aerojet Rocketdyne 3.4 kW T-140 HET as well as a patented magnetic circuit design [36]. The performance of the T-40 HET operating with krypton and xenon has been mapped by prior investigations [34].…”

“…The controllers were calibrated before each test by measuring gas pressure and temperature as a function of time in a known control volume. The mass flow controllers have an uncertainty of 0.01 mg∕s for both the cathode and anode flows [36].…”