Bulletin of the American Physical Society
65th Annual Gaseous Electronics Conference
Volume 57, Number 8
Monday–Friday, October 22–26, 2012; Austin, Texas
Session CT4: Microdischarges I |
Hide Abstracts |
Chair: Larry Overzet, University of Texas at Dallas Room: Salon DE |
Tuesday, October 23, 2012 8:00AM - 8:15AM |
CT4.00001: Characterisation of a rf micro hollow cathode discharge and its interactions with nearest neighbours Sam Dixon, Rod Boswell, Christine Charles, John Holland, Wes Cox A novel microplasma hollow cathode plasma source of 4 mm diameter and driven by 13.56 MHz is investigated using 3D sweeps of Langmuir probes in the downstream plasma expansion region. Initial results suggest that the plasma expansion is a simple diffusion from the exit orifice of the 30 mm long cylindrical source region. By making comprehensive measurements of the plasma plumes produced by two micro hollow cathode sources separated by differing distances, the mutual interaction between these components of the system have been determined with the aim of determining whether a much larger array of sources could be envisioned. The effectiveness of the plasma in dissociating reactive species was tested using SF$_{6}$ and measuring etch patterns on unbiased silicon wafers. The results have been modeled and show that it is indeed possible to produce a uniform spread of active species over large areas. [Preview Abstract] |
Tuesday, October 23, 2012 8:15AM - 8:30AM |
CT4.00002: Microhollow Cathode Sustained Discharge with Split Third Electrodes Sharmin Sultana, Jichul Shin The characteristics of stable, non-equilibrium, diffuse glow micro-hollow cathode sustained discharge (MCSD) with split third electrodes at moderate to atmospheric pressure in various flow rates are studied experimentally. Enlargement of sustained discharge volume in a split-electrode configuration is about eight times larger than that in a single planar third electrode case. At 100 Torr a maximum expansion of sustained glow discharge is measured as large as 10.3 mm with nine split third electrodes. Analytic estimate of average electron number density at the maximum expansion is measured to be as high as 2.99x10$^{10}$ cm$^{-3}$ at 5 mA third electrode current. In the presence of 0.1 slpm gas flow, the discharge region increases to 18.8 mm with corresponding estimated density of 2.48x10$^{10 }$cm$^{-3}$ at the same third electrode current. For specific pressure ranges, Faraday dark space is clearly visible near the MHCD hole. In the presence of gas flow across the gap, the sustained discharge is affected by linear momentum of the gas flow and its characteristics are altered accordingly such as current distribution over the electrodes. Feasibility of developing a flow velocimetry by using this dynamic phenomenon of MCSD with split electrodes is also studied. [Preview Abstract] |
Tuesday, October 23, 2012 8:30AM - 9:00AM |
CT4.00003: Impact of gas heating on an rf-plasma structure in a microcell at high pressure Invited Speaker: Toshiaki Makabe In a micro-plasma confined in a small volume at atmospheric pressure, we may have to consider the influence of the local heating of feed gases on the inner plasma parameters, plasma production rate etc. A capacitively coupled micro-plasma in an axisymmetric two dimensional space is theoretically investigated in Ar driven at 13.56 MHz as a typical example. The governing equation of temperature in a gas phase and on a wall is joined with conventional system equations of electrons, ions and long-lived metastable molecules as well as the potential based on the relaxation continuum (rct) model. We first stress in the micro-plasma at atmospheric pressure that an electron with intermediate energy plays an important role in plasma production through stepwise ionization in the presence of high-density metastable having a low ionization threshold. A new sustaining mechanism in the rf-CCP will be demonstrated. That is, the rf micro-plasma is sustained in the instantaneous anode-phase of the powered electrode. Secondly we bring up the enhancement of the net ionization rate by high energy electrons through the increase of the local reduced field, E(r,t)/N(r), under the appearance of a broad minimum of the number density of the heated neutral gas. In the later part of the talk, we will discuss the historically development of the basic concept, reduced-field, employed in the field of collisional low temperature plasmas. [Preview Abstract] |
Tuesday, October 23, 2012 9:00AM - 9:15AM |
CT4.00004: Particle-in-Cell Simulations of ns-pulse and RF driven microdischarges Alexandre Likhanskii, Sergey Macheret Over past decades, microplasma devices (MPDs) became popular research subject for their unique properties and wide range of applications, such as optical emitters, transistors, electron/ion sources, etc. However, MPD integration into electric circuits for consequent transition into industrial applications requires both reduction of MPD sizes and more detailed understanding of the physics behind its operation. In the presentation, we will demonstrate results of kinetic simulation of the state-of-the-art MPD, developed at UIUC and/or at Lockheed Martin, using Tech-X's code VORPAL. We will investigate the dependences of ignition voltage and relevant plasma parameters (such as EEDF, charge carrier density, etc.) during quasi steady-state MPD operation on gas pressure and applied voltage profile. [Preview Abstract] |
Tuesday, October 23, 2012 9:15AM - 9:30AM |
CT4.00005: Microwave-Excited Microplasma Thrusters Using Surface Wave and Electron Cyclotron Resonance Discharges Daisuke Mori, Tetsuo Kawanabe, Yoshinori Takao, Koji Eriguchi, Kouichi Ono Downsizing spacecrafts has recently been focused on to decrease mission costs and to increase launch rates, and missions with small satellites would bring a great advantage of reducing their risks. Such a concept supports a new approach to developing precise, reliable, and low-cost micropropulsion systems. We have studied two types of microwave-excited microplasma thrusters, using surface wave-excited and electron cyclotron resonance-excited discharges. Microwaves of S-band (4 GHz) and X-band (11 GHz) were employed to excite the plasma in these experiments, with the feed or propellant gases of Ar and He. A microplasma thruster of electrothermal type consisted of a surface wave-excited microplasma source, and a converging-diverging micronozzle to obtain the thrust. For 11-GHz microwaves at a power of 6 W, a thrust of 1.1 mN and a specific impulse of 90 s were obtained at an Ar gas flow rate of 40 sccm, where the plasma electron density was 1.2$\times$10$^{20}$ m$^{-3}$, and the gas temperature was 1.5$\times$10$^{3}$ K; under the same conditions for 4-GHz microwaves, the thrust, specific impulse, electron density, and gas temperature were 0.93 mN, 80 s, 7.0$\times$10$^{19}$ m$^{-3}$, and 8.0$\times$10$^{2}$ K, respectively. A microplasma thruster of electromagnetic type had a microplasma source excited by electron cyclotron resonance with external magnetic fields, to obtain the thrust through accelerating ions by ambipolar electric fields. Optical emission spectrum was dominated by Ar$^{+}$ ion lines in the microplasma thruster of electromagnetic type, owing to higher electron temperatures at lower feed-gas pressures. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700