Integrated Liquid Bismuth Propellant Feed System

A prototype bismuth propellant feed and control system was constructed and operated in conjunction with a propellant vaporizer. An electromagnetic pump was used in this system to provide fine control of the hydrostatic pressure, and a new type of in-line flow sensor was developed in an attempt to provide an accurate, real-time measurement of the mass flow rate. High-temperature material compatibility was a driving design requirement for the pump and flow sensor, leading to the selection of Macor for the main body of both components. Post-test inspections of both components revealed no degradation of the material. In separate proof-of-concept experiments, the pump produced a linear pressure rise as a function of current that compared favorably with theoretical pump pressure predictions, with a pressure of 10 kPa at 30 A. Preliminary flow sensor measurements have been made at a bismuth flow rate of 6 mg/s ± 6%. A real-time controller was successfully used to control the entire system, simultaneously monitoring all power supplies and performing data acquisition duties.