Bulletin of the American Physical Society
70th Annual Gaseous Electronics Conference
Volume 62, Number 10
Monday–Friday, November 6–10, 2017; Pittsburgh, Pennsylvania
Session WF1: Reconfigurable and Interacting Plasmas |
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Chair: Katharina Stapelmann, North Carolina State University Room: Salon D |
Friday, November 10, 2017 10:00AM - 10:30AM |
WF1.00001: Plasmas for Reconfigurable Radio-Frequency Systems Invited Speaker: Sergey Macheret The presentation discusses properties of weakly ionized plasmas from the standpoint of their potential application to tunable and reconfigurable radio-frequency (RF) electronics: antennas, resonators, filters, limiters etc.~Plasmas have important advantages in comparison with other (e.g. semiconductor, ferrite etc.) solutions, especially in high-power regimes. Although the RF applications motivate the plasma research, the focus of this presentation is on the relevant fundamental aspects.~First, we show that plasmas can combine resistive, capacitive, and inductive properties and that all three can be tuned over very wide ranges. We then discuss recent proof-of-principle experiments on using simple gas discharges as tunable elements in resonant LC filters, resonators, and limiters. We then turn to plasma antennas and show that such antennas generally have lower gain than metallic antennas do, but the cross-coupling between different elements of an array is also lower, which is an important plasma advantage. Finally, we discuss the critical problem of Johnson-Nyquist noise and show that although conventional plasma antennas can be very ``noisy'', sustaining the plasma by nanosecond repetitive pulses could enable low-noise plasma antennas. [Preview Abstract] |
Friday, November 10, 2017 10:30AM - 10:45AM |
WF1.00002: Plasma Photonic Crystals using Arrays of Microplasma Jets Devices Hee Jun Yang, Jinhong Kim, Sung-Jin Park, J. Gary Eden Photonic crystals composed of microplasma and air can be made with arrays of microplasma jets devices. Compared to the solid-state photonic crystals, plasma photonic crystals are reconfigurable at electronic speeds. Also, both spatial period and refractive index can be controlled in plasma photonic crystals. Diameter of each microplasma jet is 400 $\mu $m and pitch to pitch distance is 1 mm and operated in He gas flow. With a distributed Bragg reflector (DBR) structure with periodicity of 1 mm, attenuation of wave occurs at 150 GHz. Calculations and characteristics of plasma photonic crystals will be discussed. Two-dimensional microplasma photonic crystals at 157 GHz have been demonstrated. [Preview Abstract] |
Friday, November 10, 2017 10:45AM - 11:00AM |
WF1.00003: Multiscale numerical modeling in plasma metamaterial systems Dylan Pederson, Konstantinos Kourtzanidis, Laxminarayan Raja Plasmas have found application in metamaterials (MM)as a negative or near-zeropermittivity component. The permittivity of a plasma depends on its electron density, which can be influencedby an applied field. This means that plasmas can be used in MM to actively control the passageof incident waves, leading to applications in switching and power limiting. Numerical modeling of MMis inherently challenging due to disparate spatial and temporal scales. MMcomponents are typically much smaller than the wavelength they're designed to interact with. When a microplasma is generated by the MM, then the scale lengthsbecomeeven more disparate. Furthermore, capturing interesting physics in the plasma sheath region poses an even harder challenge. In all, plasma MMscale lengths and times can vary over or orders of magnitude. Flux-conservative methods on tree-based grids have shown to be effective in simulating multiscale plasma dynamics in static fields. In this work we address the corresponding techniques for multiscale modeling of plasma dynamics in dynamic fields, and the treatment of those dynamic fields via a multiscale Finite-Difference Time-Domain technique. Usingthese techniques, we can adaptively refine the simulation mesh as the plasma moves in the domain. [Preview Abstract] |
Friday, November 10, 2017 11:00AM - 11:15AM |
WF1.00004: Ultrasound Generation from Arrays of Microcavity Plasmas Jinhong Kim, Sung-Jin Park, Gary Eden The generation of ultrasound (20 -- 250 kHz) by arrays of microcavity plasmas has been demonstrated. When the microplasmas are excited by a sinusoidal voltage (20 -- 60 kHz), harmonics as high as m $=$ 12 are detected by a condenser microphone. Each of the ultrasound harmonics matches the harmonics observed in the Fourier representation of the microplasma array current. The intensity of ultrasound can be adjusted by altering the geometry of the microcavity plasmas. Due to the limited bandwidth of the condenser microphone, the highest detectable frequency of in these experiments is 250 kHz at present. As an alternative to microphone detection, a modified Michelson interferometer has been constructed and has successfully detected ultrasound emission from the plasma arrays at frequencies up to 400 kHz. [Preview Abstract] |
Friday, November 10, 2017 11:15AM - 11:30AM |
WF1.00005: Research on Initial Plasma Development in the Laser Triggered Vacuum Switch Yuchen Liu, Zhenghao He In this paper, a multi-electrode laser-triggered vacuum switch (LTVS) is developed to meet the requirements of the pulsed power technology. A pre-breakdown current trigger circuit has been built to investigate the initial process before the switch closes. Under the effects of the pulse laser, the target material generates initial plasma, then the plasma develops and increases because of the effects from electric field. It is found that the initial plasma current increases with the increase of the main gap voltage and the laser energy, and the initial charge amount generated by the laser trigger is approximately the same as the logarithm of the peak power of the laser. [Preview Abstract] |
Friday, November 10, 2017 11:30AM - 11:45AM |
WF1.00006: Next generation high-current switching devices, based on Cs-Ba plasma. Aleksandr Mustafaev, Victor Kuznetsov, Vladimir Soukhomlinov, Artem Grabovskiy In this talk we discuss the research into plasma's electro kinetic parameters of Knudsen high-current diode and triode switching devices. It was found that the phenomenon of spontaneous current breakage has a big influence on the efficiency of discharge quenching. Unique regimes for grid discharge quenching were attained: the increase in the modulated power is accompanied by the decrease in the power consumption. Unprecedented energy parameters were obtained: stable frequency modulation in the range from 1 to10 kHz, an anode potential of 50 V, the electric power density of 5 kW/cm$^{\mathrm{2\thinspace }}$and the efficiency more than 95{\%}. Experiments with the grid-less modulator based on the thermionic diode demonstrate the following results: The current modulation is formed as result of plasma structure generation in the electrode gap without applying any external forces. The experiments on the Cs-Ba Knudsen diode demonstrate the feasibility of creating a full current modulation at an ignition voltage of 5\textellipsis 6~V and a discharge current density of \textasciitilde 10 A/cm$^{\mathrm{2}}$. At a gap of 0.2\textellipsis 2 mm, a stable current and voltage modulation of 5\textellipsis 20~kHz frequency exists in a Cs-pressure range from 1.5\textbullet 10$^{\mathrm{-3}}$ to 3.5\textbullet 10$^{\mathrm{-3}}$Torr. The possibility of the modulation process control via additional external forces was discovered. [Preview Abstract] |
Friday, November 10, 2017 11:45AM - 12:00PM |
WF1.00007: FEM Simulation of Antenna Self-Inductance Effects in ICP Makoto Moriyama, Keiji Nakamura, Ivan Ganachev Inductively coupled plasma (ICP) has been widely used in the manufacturing of semiconductor devices. It is generated by inductive electric (E) field produced by the RF current of a coil antenna isolated from the plasma by a dielectric window. Large-amplitude RF voltage appears along the coil due to the coil's self-inductance resulting in strong electrostatic E-field near the antenna terminals. This amounts to capacitive coupling and increases the negative (with respect to the plasma bulk) self-bias potential on the window surface Acceleration in this sheath produces more energetic ions, and the ion bombardment often causes unwanted window sputtering. In this study we estimate sheath formation and self-bias voltage using commercially available FEM software. In one example ion bombarding energy of about 100 eV was observed in a 20 mTorr argon ICP driven by 13.56 MHz 40 App RF current in a one-turn coil antenna. The self-induced RF voltage at the antenna terminals was 1200 Vpp. The plasma was cylindrical with radius of 30 cm and height of 15 cm, which are typical conditions and size for plasma sources used in semiconductor device manufacturing. Next we will aim to evaluate antenna and electrostatic-shield designs for reducing the unwanted capacitive coupling [Preview Abstract] |
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