Bulletin of the American Physical Society
71st Annual Gaseous Electronics Conference
Volume 63, Number 10
Monday–Friday, November 5–9, 2018; Portland, Oregon
Session SF2: Thrusters (Other) |
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Chair: David Go, University of Notre Dame Room: Oregon Convention Center A105 |
Friday, November 9, 2018 8:00AM - 8:15AM |
SF2.00001: Laboratory experiments on a plasma-flow-state transition from diverging to stretching a magnetic nozzle Kazunori Takahashi, Akira Ando Axial magnetic field induced by a plasma flow in a divergent magnetic nozzle is measured when injecting the plasma flow from a radiofrequency (rf) plasma source located upstream of the nozzle. The source is operated with a pulsed rf power of 5 kW, and the high density plasma flow is sustained only for the initial 100 microseconds of the discharge. The measurement shows a decrease in the axial magnetic field near the source exit, whereas an increase in the field is detected at the downstream side of the magnetic nozzle. These results demonstrate a spatial transition of the plasma-flow state from diverging to stretching the magnetic nozzle, occurring more upstream than thought, where the importance of both the Alfven and ion Mach numbers is shown. [Preview Abstract] |
Friday, November 9, 2018 8:15AM - 8:30AM |
SF2.00002: Abstract Withdrawn
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Friday, November 9, 2018 8:30AM - 8:45AM |
SF2.00003: Water ion thrusters using micro ECR discharges for CubeSat projects Yoshinori Takao, Kengo Nakamura, Yosuke Sato, Hiroyuki Koizumi The use of CubeSats has dramatically been increased since 2013 because of the low cost and shot development period. Since the limitation of the size, weight, and power, only a few CubeSats have propulsion system for their missions, where their propulsion performance is still very low. Ion thrusters are one of the high-performance propulsion systems and a promising candidate for CubeSat missions requiring high $\Delta v$ (change in velocity) if the gas storage and feeding system is significantly miniaturized. Here, an ion thruster using water as the propellant has been proposed for 10-kg class CubeSats and its discharge characteristics have been investigated by three-dimensional particle-in-cell simulation with Monte Carlo collisions (PIC-MCC) and the direct simulation Monte Carlo (DSMC) method. The plasma source employs 4.2-GHz microwaves for the discharge and the size of the discharge chamber is 20 x 20 x 4 mm$^3$. Many reactions, such as ionization, rotational and vibrational excitation, attachment, detachment, charge transfer, etc., are incorporated in the MCC process. The simulation results have indicated that H$_2$O$^+$ and OH$^+$ are the major components of ion species in the discharge, which is a favorable result since these species dominantly contribute to the thrust. [Preview Abstract] |
Friday, November 9, 2018 8:45AM - 9:00AM |
SF2.00004: Spatiotemporal plasma heating mechanisms in a radio-frequency electrothermal microthruster James Dedrick, Scott Doyle, Andrew Gibson, Teck Ho, Roderick Boswell, Christine Charles, Mark Kushner Low power, compact and neutralizer-free propulsion sources are of significant interest for meeting the challenges of space missions with small satellites. Radio frequency (rf) electrothermal plasma thrusters provide enhanced spatial control of power deposition to the propellant for increased thrust. In this study, we investigate the mechanisms for electron and neutral-gas heating in an rf 13.56 MHz electrothermal microthruster operating in argon at 1.4-1.7 Torr plenum pressure. Two dimensional, fluid-kinetic simulations undertaken with the Hybrid Plasma Equipment Model corroborate measurements of the electron-impact excitation rate via phase-resolved optical emission spectroscopy. The relative role of each heating mechanism on the spatially resolved power deposition is investigated across the alpha-gamma mode transition and pressure gradient on-axis. Prospects for achieving enhanced control of the sheath dynamics, ion-power fraction and neutral-gas heating via “tailored” voltage waveforms are also discussed. [Preview Abstract] |
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