Experimental Investigation into the Enhanced Diamagnetic Perturbations and Electric Currents Downstream of the High Power Helicon Plasma Thruster

Thesis (Ph.D.)--University of Washington, 2013The high power helicon (HPH) is a compact plasma source that can generate downstream densities of 1017-1018 m-3 and directed ion energies of 50-70 eV, without the need for grids that can corrode with use or requiring a larger engine diameter. Generating a quasi-neutral plasma beam that can stay collimated and impart significant power and momentum to a distant target in space has a variety of potential applications including beamed propulsion and the remediation of space debris. In order to understand and improve the coupling mechanism between the helicon source antenna and the downstream plasma, measurements were made in the plasma plume downstream of the propagating wave magnetic field and the diamagnetic perturbation of the background magnetic field with the presence of the plasma. This magnetic field perturbation (ΔB) peaks at more than 15 gauss in magnitude downstream of the plasma source and propagates tens of centimeters downstream, cancelling the base magnetic field provided by the experiment as it propagates. Taking the curl of this measured magnetic perturbation suggests a peak current density of 20 kA m-2. These diamagnetic perturbations and electric currents were correlated with an increase in wave-plasma coupling and increased acceleration of the plasma particles downstream. In order to increase the energy coupled into the plasma and drive a larger diamagnetic perturbation a further distance downstream a second, larger radius antenna was added roughly one wavelength downstream co-axially with the first antenna and driven in phase with the first. This resulted in improved collimation of the plasma beam over a meter downstream, increased diamagnetic perturbation, and an increase in the ion energies downstream of more than 20 eV. This work includes the development of a high power plasma source that is capable of generating a dense, collimated plasma beam with exhaust velocities comparable to devices of similar power levels but in a compact size without the need of electric grids; as well as measuring diamagnetic plasma perturbations that are larger than in any similar plasma experiment previously published, suggesting new capabilities for studying high beta (but cold and directed) plasmas in a laboratory setting

Development of a Rockoon Launch Platform and a Sulfur Fuel Pulsed Plasma Thruster CubeSAT

Amateur rocket launches are unable to reach heights much above 30 km due to the high drag of the dense lower atmosphere. Using a balloon to rise to an altitude of 30 km before launching is one means to increase a rockets range. An overview of the concept and a summary of the launch history for the University of Washington rockoon (rocket / balloon) program are given. Such a system will be capable of providing an inexpensive and reduced complexity launch method for student projects. Additionally, the university has recently opened a CubeSAT laboratory to give students hands-on experience with satellite hardware. Once in orbit, CubeSAT missions are limited, in part, due to an inability of low power thrusters to offset atmospheric drag. Recent results show that a coaxial sulfur-fuel Pulsed Plasma Thruster can provide a impulse/energy ratio of 20 mN/kW from a 10 J discharge, double of what a similar geometry Teflon variant is capable of. This increase in performance can provide CubeSATs the propulsion necessary for station-keeping in orbit. With launches planned over the next five years, the University of Washington aims to launch a 3U CubeSAT from a rockoon on a suborbital flight as a student project