Vacuum Test of a Novel Green-Propellant Thruster for Small Spacecraft

摘要

The Propulsion Research Laboratory at Utah State University has recently developed an inherently safe, low cost, and "green" alternative to in-space propulsion systems based on hydrazine. When fully developed, this technology has the potential for "drop in" replacement of many hydrazine propulsion applications. The power efficient system can be started, stopped, and restarted with a high degree of reliability. Prototypes with thrust levels varying from 4.5 to 900 N have been developed and tested. Previously, industry standard market assessment tools had estimated the TRL of this technology between 3 and 4, with a primary deficiency being systems assessments in a vacuum environment. To upgrade the TRL, a series of tests of a flight weight 25-N thruster with 3-D printed fuel grains was performed at the NASA Marshall Space Flight Center's ER-23 Propulsion Research Laboratory. Both ambient and vacuum test results are presented. These results clearly demonstrate the advantages of additive manufacturing including rapid, low-power ignition, low O/F shift, system scalability, and high specific impulse. Multiple burn tests allowed statistical characterization of ignition timing and burn-to-burn performance variability. Results demonstrating soft-vacuum specific impulse values exceeding 275 s are presented. When scaled to hard-vacuum conditions, specific impulse is expected to top 300 s.