An experimental investigation of alternative propellants for the helicon double layer thruster

Abstract

Ion energy distribution functions are measured using a retarding field energy analyser located 7.5 cm downstream of a helicon double layer plasma source, respectively, operating with four molecular gases: nitrogen (N 2), methane (CH 4), ammonia (NH 3) and nitrous oxide (N 2 O). For radiofrequency powers of a few hundred watts, and a magnetic field diverging from about 0.013 T (130 G) in the source to about 0.001 T (10 G) in the exhaust, an ion beam is detected for each propellant over a very similar operating pressure range (∼0.023 Pa (0.17 mTorr) to ∼0.267 Pa (2 mTorr)), as a result of spontaneous electric double layer formation near the exit of the plasma source. The characteristics of the ion beam versus operating pressure closely follow those previously obtained in argon, xenon and hydrogen. The ion beam exhaust velocity in space is found to be in the 17-19 km s −1 range in N 2 , 21-27 km s −1 range in CH 4 and NH 3 and 14-16 km s −1 range in N 2 O.

Performance characterization of a helicon double layer thruster using direct thrust measurements

“…The lifetime of the HDLT is not limited by grid erosion mechanisms and the thruster produces a quasi neutral plume, therefore a hollow cathode or alternative beam neuralising device is made redundant. Proof of concept and thruster functionality has been demonstrated for a variety of propellants, magnetic field topologies and source tube dimensions [3,4,5,6].…”

Temporal evolution of double layers in pulsed helicon plasmas

“…The resultant ion acceleration to supersonic speeds and the characteristic high ion densities of helicon discharges motivated researchers from the Australian National University ͑ANU͒ to propose the helicon double layer thruster ͑HDLT͒ concept. 2 Although the specific impulse and thrust of the HDTL are low compared to conventional thrusters, the possibility of electrically steering the ejected ion beam, 3 stable operation at very low pressure in a variety of gases, 4 and the possibility of high energy efficiency 5 are sufficiently intriguing that HDLT optimization studies have continued. For example, recent studies have shown that the overall energy efficiency can be significantly improved by replacing the heavy solenoids used to generate the axial magnetic fields with smaller and lighter permanent magnets.…”

Space Simulation Testing of the Helicon Double Layer Thruster Prototype

“…nitrogen, nitrous oxide, oxygen and carbon dioxide (Charles, 2004;Charles et al, 2006Charles et al, , 2008bCharles, 2009;Charles et al, 2009).…”