Bulletin of the American Physical Society
58th Annual Meeting of the APS Division of Plasma Physics
Volume 61, Number 18
Monday–Friday, October 31–November 4 2016; San Jose, California
Session UO7: Electric Propulsion and Water-Plasma Interactions |
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Chair: Kristina Lemmer, Western Michigan University Room: 212 AB |
Thursday, November 3, 2016 2:00PM - 2:12PM |
UO7.00001: ABSTRACT WITHDRAWN |
Thursday, November 3, 2016 2:12PM - 2:24PM |
UO7.00002: Laser characterization of electric field oscillations in the Hall thruster breathing mode Christopher Young, Andrea Lucca Fabris, Natalia MacDonald-Tenenbaum, William Hargus Jr., Mark Cappelli Hall thrusters are a mature technology for space propulsion applications that exhibit a wide array of dynamic behavior, including plasma waves, instabilities and turbulence. One common low frequency (10--50 kHz) discharge current oscillation is the breathing mode, a cycle of neutral propellant injection, strong ionization, and ion acceleration by a steep potential gradient. A time-resolved laser-induced fluorescence diagnostic non-intrusively captures this propagating ionization front in the channel of a commercial BHT-600 Hall thruster manufactured by Busek Co. Measurements of ion velocity and relative ion density (using the $5d[4]_{7/2} - 6p[3]_{5/2}$ Xe II transition at 834.95 nm, vacuum) reveal a dynamic electric field structure traversing the channel throughout the breathing mode cycle. [Preview Abstract] |
Thursday, November 3, 2016 2:24PM - 2:36PM |
UO7.00003: Evaluating the accuracy of recent electron transport models at predicting Hall thruster plasma dynamics Mark Cappelli, Christopher Young We present continued efforts towards introducing physical models for cross-magnetic field electron transport into Hall thruster discharge simulations. In particular, we seek to evaluate whether such models accurately capture ion dynamics, both averaged and resolved in time, through comparisons with measured ion velocity distributions which are now becoming available for several devices. Here, we describe a turbulent electron transport model [1] that is integrated into 2-D hybrid fluid/PIC simulations of a 72 mm diameter laboratory thruster operating at 400 W. We also compare this model's predictions with one recently proposed by Lafluer et al [2]. Introducing these models into 2-D hybrid simulations is relatively straightforward and leverages the existing framework for solving the electron fluid equations. The models are tested for their ability to capture the time-averaged experimental discharge current and its fluctuations due to ionization instabilities. Model predictions are also more rigorously evaluated against recent laser-induced fluorescence measurements of time-resolved ion velocity distributions [3]. [1] M.A. Cappelli, C.V. Young, E. Cha, and, E. Fernandez, Physics of Plasmas 22, 114505 (2015). [2] T. Lafleur, S. D. Baalrud, and P. Chabert, Phys. Plasmas 23, 053503 (2016). [3] C.V. Young, A. Lucca Fabris, and M.A. Cappelli, IEPC 2015-437p, 34th International Electric Propulsion Conference Hyogo-Kobe, Japan, July 4--10, 2015. [Preview Abstract] |
Thursday, November 3, 2016 2:36PM - 2:48PM |
UO7.00004: Performance Characterization of Ion Thruster with Isolated Magnet Rings Neil Arthur, John Foster Many ion sources use magnetic multipole confinement to increase the primary electron containment length. The magnetic circuit increases ion source efficiency and plasma density. A multipole source consists of rings or rows of magnets of alternating polarity. In multipole sources, the bulk of the discharge current is collected at the magnet surface, through the relatively narrow leak width. Ion engines for space propulsion are one application of multipole ion sources. Here we characterize a four ring, broad beam ion source under simulated beam extraction using typical performance metrics for ion engines while biasing the magnetic rings individually. By biasing the magnetic cusps, through isolated, conformal electrodes placed on the magnet rings, the current distribution to each individual cusp can be modified. The effect of ring bias on ion beam current, propellant utilization efficiency, and discharge losses is measured over a broad range of ring bias. Previous experiments have shown that the current distribution to the rings can be controlled, and this current distribution has tangible effects on the plasma properties and ion source operation. The goal is to gain insight into which magnetic ring current distributions will yield enhancements in engine performance. [Preview Abstract] |
Thursday, November 3, 2016 2:48PM - 3:00PM |
UO7.00005: ABSTRACT WITHDRAWN |
Thursday, November 3, 2016 3:00PM - 3:12PM |
UO7.00006: Uncertainty propagation in modeling of plasma-assisted hydrogen production from biogas Shadi Zaherisarabi, Ayyaswamy Venkattraman With the growing concern of global warming and the resulting emphasis on decreasing greenhouse gas emissions, there is an ever-increasing need to utilize energy-production strategies that can decrease the burning of fossil fuels. In this context, hydrogen remains an attractive clean-energy fuel that can be oxidized to produce water as a by-product. In spite of being an abundant species, hydrogen is seldom found in a form that is directly usable for energy-production. While steam reforming of methane is one popular technique for hydrogen production, plasma-assisted conversion of biogas (carbon dioxide + methane) to hydrogen is an attractive alternative. Apart from producing hydrogen, the other advantage of using biogas as raw material is the fact that two potent greenhouse gases are consumed. In this regard, modeling is an important tool to understand and optimize plasma-assisted conversion of biogas. The primary goal of this work is to perform a comprehensive statistical study that quantifies the influence of uncertain rate constants thereby determining the key reaction pathways. A 0-D chemical kinetics solver in the OpenFOAM suite is used to perform a series of simulations to propagate the uncertainty in rate constants and the resulting mean and standard deviation of outcomes. [Preview Abstract] |
Thursday, November 3, 2016 3:12PM - 3:24PM |
UO7.00007: Vortex Stabilized Plasma for Rapid Water Disinfection {\&} Pharmaceutical Degradation Ady Hershcovitch Good quality drinking water is dwindling for large segments of the world population. Aggravating the problem is proliferation of antibiotics in the water supply, which give rise to drug resistant pathogens. One option for water supply increase is recycling waste and polluted water by inexpensive, environmentally friendly methods. Presently disinfection uses chemicals and UV radiation. Chemicals are limited by residual toxicity, while UV consumes much electricity. Current methods can remove only certain classes of drugs due to their large variety of physical and chemical properties. Plasmas in water are very attractive for degrading all pharmaceuticals and deactivating pathogens: intense arc current can physically break up any molecular bonds. UV radiation, ozone, etc. generation inside the water volume disinfects. Present utilized plasmas: glow, pulsed arcs are not power efficient; vortex stabilized plasmas are power efficient that can advance water treatment state-of-the-art by orders of magnitude. Proposed technique\textbf{ }features novel components facilitating large diameter vortex stabilized in-water arcs with optimized plasma parameters for maximal UV-C emission; and harvests hydrogen centered by the vortex. [Preview Abstract] |
Thursday, November 3, 2016 3:24PM - 3:36PM |
UO7.00008: ABSTRACT MOVED FROM U07.8 to JP10. |
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