Performance characterization of a high efficiency gas-fed pulsed plasma thruster

Abstract

We present a characterization of the performance of a recently developed gas-fed pulsed plasma thruster (GF-PPT) at low discharge energies (≤5 J). The impulsive thrust measurements were made using EPPDyL's high-accuracy interferometric microthrust stand. The thruster is best suited for small satellite applications and is operated in an unsteady pulsed mode (3 µs/pulse). It is the result of a series of design iterations aimed at achieving the highest thrust efficiencies for unsteady electromagnetic acceleration at low discharge energies. The use of advanced nonlinear magnetic switching technology, which insured a total system inductance of 3-4 nH, combined with an electrode geometry and radial gas injection that favor low profile losses, yielded a total efficiency of 50% at 5 J with argon (at an impulse bit of 32 µNs and a mass bit of .2 µg/shot). This is the highest measured efficiency ever reported for a PPT at this low energy level. Moreover, the low mass utilization efficiency problem that plagued previous gas-fed pulsed

Dimensionless performance model for gas-fed pulsed plasma thrusters

“…[4] and [9]. The impulse data taken with small mass bit values in those papers is currently under investigation for contamination due to diffusion pump oil and should not be considered a valid indication of GFPPT performance.…”

Gas-Fed Pulsed Plasma Thrusters: Fundamentals, Characteristics and Scaling Laws

“…A detailed description of the SRL family of GFPPTs has been given in other papers [53,44,10] and will only be summarized here. A steady-state power supply charges the PPT capacitor bank which is discharged at a finite duty cycle between two co-axial electrodes where gas has been injected just before the pulse (see Fig.…”

“…Recent work has resulted in a complete solution [53] to this problem by using state-of-theart pulse power technology raising the propellant utilization efficiency to well above 90%. This solution is illustrated in Fig.…”

“…Previous performance measurements at EPPDyL [53,44] as well as Fairchild Republic [4] in 1966 have been shown to be influenced by diffusion pump oil contamination. A thin oil-film is believed to build up on the thruster electrodes between impulse measurements and influence the discharge dynamics due to the small mass bit nature (< 2^ig per pulse) of GFPPT operation.…”

“…Different designs of ignitors have been tested in the past by measuring the voltage and current waveforms to infer the energy efnciency [69] but few images of the initiation history of a GFPPT discharge exist in the literature. Recently, a family of high-repetition rate co-axial geometry GFPPTs have been introduced and tested by Science Research Labs, Inc. and Princeton University [53,44]. The high-repetition rate allows a propellant utilization of nearly 100% by stringing multiple pulses together into a tight burst.…”