High Power Helicon Thruster

The High Power Helicon (HPH) plasma thruster under development at MSNW and the University of Washington is an emerging electrode-less in-space thruster that is potentially capable of high thrust level (1-2 Newtons) at moderate power levels of 20 to 50 kW. Unlike previous lower power (2 to 5 kW) helicon thruster schemes, which have been shown to produce moderate temperature of 5 to 10 eV thermal plasmas, the HPH axial and radial plasma characteristics show that the plasma is created in the helicon coil and is then accelerated in the axial direction downstream away from the HPH. The bulk acceleration of the plasma is believed to be due to a directional coupling of the plasma electrons with the helicon wave field, which in turn transfers energy to the ions via an ambipolar electric field. Downstream energy distribution functions obtained with an ion energy retarding field analyzer show a highly non-thermal or beamlike supersonic ion flow away from the HPH thruster. The system is very versatile and is capable of operation at variable input power levels in either pulsed or DC modes. Additionally, the HPH system has been shown to operate utilizing different propellants with hydrogen, nitrogen, argon and xenon having been tested to date. Baseline Isp levels for argon, nitrogen and hydrogen are 1500, 3000 and 5000 respectfully, giving some variability in Isp and thrust by the choice of propellants or propellant mixtures. Current work focuses on the optimization of the system and increasing output plasma power levels.