2017 IEEE International Conference on Plasma Science (ICOPS)最新文献

{"title":"Absolute Instability at the Lower Band Edge in a Traveling Wave Tube","authors":"F. Antoulinakis, Y. Lau, P. Wong, A. Jassem","doi":"10.1109/PLASMA.2017.8496064","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496064","url":null,"abstract":"We provide a close examination of the beam mode and its interaction with the circuit mode in the immediate vicinity of the lower band edge in a traveling wave tube. We model the circuit mode as a hyperbola in the (w, k) plane in the immediate vicinity of the lower band edge, where w is the frequency and k is the wavenumber. We find that an absolute instability may arise, according to the Briggs-Bers criterion [1], if the beam current is sufficiently high, even if the beam mode intersects with the circuit mode at a point in the (w, k) plane with a positive group velocity. This threshold condition is deduced analytically and confirmed by numerical calculations. When the threshold current is exceeded, the Green’s function [1], at a fixed position, exponentiates in time as t to the 1/3 power initially, but as (wi*t) at later time, where wi is the imaginary part of the unstable polepinch root of w according to the Briggs-Bers criterion [1]. This finding differs from some previous works [2, 3]on absolute instabilities at the lower band edge, and points to the vulnerability to absolute instabilities at both the upper and lower band edges of a TWT.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114447493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of Carrier Gas on Nanosecond-Pulsed Plasma Discharge Generated in a Water Film Plasma Reactor","authors":"Huihui Wang, R. Wandell, B. Locke","doi":"10.1109/PLASMA.2017.8496199","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496199","url":null,"abstract":"Plasma discharge with liquid water has been widely studied due to its potential application in water treatment and chemical synthesis. Hydrogen peroxide, mainly formed by the recombination of hydroxyl radicals, is the major stable product of the plasma discharge with liquid water. The production rate of hydrogen peroxide is affected by operating conditions such as reactor type and input power1 2. In our previous work3, a nanosecond power supply with adjustable pulse width, input voltage and pulse frequency, was used to investigate how input power influences the hydrogen peroxide production in the water film reactor. In the present study we expand upon the previous work with this nanosecond pulsed plasma discharge by considering the influence of carrier gas (argon and helium) on the plasma properties and the formation of hydrogen peroxide. We hypothesize that the carrier gas influences the plasma properties that in turn affect the hydrogen peroxide production rate. The plasma properties, including electron density, gas temperature, and plasma volume, and the hydrogen peroxide production rate are measured in argon, helium, and argon/helium mixtures. We found that the helium plasma is more diffusive compared with the argon plasma. In addition, the helium plasma has a larger volume and lower electron density and gas temperature. These results may be due to the higher thermal conductivity of helium compared to argon. We also found that by combining helium with argon, thus increasing the thermal conductivity over that of pure argon, the plasma became more diffusive with the increasing percentage of helium in the gas mixture.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114679219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating a Lower Limit for the Magnetic Field in a TWT*","authors":"Necati Haytural, L. Oksuz, A. Gulec, F. Bozduman, Hakan Yeşiltepe","doi":"10.1109/PLASMA.2017.8496118","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496118","url":null,"abstract":"Stable operation is one of the challenging difficulties of a traveling wave tube when it comes to designing. Mismatches at the couplers, spreading of the beam more than necessary due to space-charge forces etc. may lead to self-excitations of the tube. The spreading of the beam may also lead to backward wave oscillations[1].For this reason the beam focusing is an important matter on TWT operation and strong magnetic fields are required for the confinement of the beam.In this study a lower limit for the magnetic field will be investigated for given beam parameters. CST Studio Suite will be used for modelling and simulations of a Ku band TWT [2].","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114989048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of varying end-capacitance in external antenna for inductively coupled plasma","authors":"D. H. Kim, H. Rhee, S. Nawaz, S. Yoon","doi":"10.1109/PLASMA.2017.8496033","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496033","url":null,"abstract":"Summary form only given. Modern inductively coupled plasma (ICP) gained a great interest in plasma-assisted material processing in semiconductor industry. This implied by key properties of ICP having high-density, uniform plasma at low pressure. We report the effect of endcapacitance dependency for ICP. The efficiency of ICP is normally measured via inductive coupling efficiency between antenna coil and the plasma 1. Our discharge chamber had 200mm diameter and consisted of three-turn external cylindrical antenna coil through pi-type matching network. End-capacitance is used to suppress electrostatic coupling to plasma. The suppression is one of key issue from material processing in field of semiconductor industry, as it causes sputtering of dielectric materials. In this work, the plasma density and the antenna voltages are measured by changing the end-capacitance. The end-capacitance herein is a vacuum variable capacitance (VVC) ranging from 50 pF to 500 pF. While adjusting the value of capacitor, V-I value flowing through antenna was measured. The test RF discharge parameters are 13.56 MHz, applied up to 4000 W, gas pressure was maintained constant 0.2 Torr. For changing endcapacitance we measured the voltage at two points, before and after antenna coil namely Vin and Vout, using a highvoltage probe. E-H mode transition power and ion current are measured with respect to range of end-capacitance. Ion Current was measured using a floating harmonic method. With increasing the end-capacitance, the ratio of Vout/Vin has increased simultaneously. Less RF power is required for the E-H mode transition when VVC is tuned to higher capacitance. The inductive coupling is more efficient for the case where E-H mode transition is lower. The measured ion current is 2 times higher for changing Vout/Vin ratio from 0.33 to 7.15. The plasma density of ICP is associated with the resonance of inductance and capacitance of the antenna coil. The impedance of antenna, which is adjustable by changing the end-capacitance, determines the plasma-potential oscillation, voltage and current on the coil. With endcapacitance optimization, the plasma density is increased by lowering the antenna wall loss and accelerating ions by selfbias DC voltages. Varying the end-capacitance of antenna and to find optimum capacitance for antenna design has enabled to build effective ICP system.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"392 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116392748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of an Electron-Beam Pumped Arf Excimer Laser *","authors":"T. Petrova, G. Petrov, M. Wolford, A. Schmitt, J. Giuliani, S. Obenschain","doi":"10.1109/PLASMA.2017.8496233","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496233","url":null,"abstract":"We present here initial efforts to advance the modeling of electron-beam-pumped ArF lasers. These efforts will be tested against experiments using the NRLElectrafacility. The advantages of using ArF as a driver for direct drive laser fusion compared to KrF [1]are: shorter wavelength (193 nm for ArF* vs. 248 nm for KrF*) and broader bandwidth. Use of ArF driver should lead to more robust higher-energy-gain fusion implosions than KrF, with an even larger advantage over the 351 nm laser technology used on NIF. The smaller absorption cross section by F2 with ArF [2]is an advantage in constructing large, high-energy amplifiers. In addition, it may have higher intrinsic efficiency than KrF [3]. A theoretical model of an e-beam pumped ArF* excimer laser is under development. One of the goals of this work is to understand the energy deposition in Ar-F2mixture for ArF lasers and compare to Ar-Kr-F2mixture for KrF lasers [4, 5]. The collisional rates with electrons are obtained as a function of F2concentration and power deposition by solving the steady-state Boltzmann equation for the electron energy distribution function. We use the concept of excitation-to-ionization ratios to obtain slowly varying rates over a wide range of input parameters such as beam power, gas pressure, and initial gas composition. These rates are coupled to a 1D time-dependent plasma chemistry based on NRLOrestessuite of numerical models. It includes plasma chemistry reactions and vibrational population kinetics of ArF* molecules, coupled to a 3D-radiation transport for the amplified spontaneous emission (ASE). The input parameters are the e-beam temporal profile, gas composition, and system geometry (type of laser amplifier configuration with initial laser seed characteristics). Measurable plasma parameters, such as species concentrations, electron and gas temperatures, as well as laser parameters, such as small signal gain, non-saturable absorption, saturated laser intensity, and AES are calculated as a function of input power and gas composition in the e-beam high-power regime. The model results are compared with the limited experimental measurement literature for ArF lasers.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123592630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic 3D Microplasma Photonic Crystal By 3D Printing","authors":"P. P. Sun, P. P. Sun, S. Zhong, J. Eden, Runyu Zhang, P. Braun, Wenyuan Chen","doi":"10.1109/PLASMA.2017.8496314","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496314","url":null,"abstract":"Three dimensional microplasma photonic crystal (3D MPPhC) is first time realized through 3D printing method. The layerlayer building method is only one embodiment for building the microstructures to confine the plasma. The 3D MPPhC proposed here for achieving highly tunable and reconfigurable material systems for electromagnetic responses in the millimeter wave or extremely high frequency regimes. The plasma crystal periodic structure arrays confined in the microstructures have been successfully realized within a volume large than 16.25 cm3, for example, can serve as a reconfigurable bandpass filter, beam splitter or router, attenuator, or phase shifter for frequencies up to and beyond 1THz. The mm-wave transmission responses from 110 – 170 GHz have been recorded with the strong responses. The dynamic tunings are demonstrated through the addressability of the microplasma array in three dimensions, including electron density, collisional frequency and crystal latter constants. We believe the capability of controlling the arrays of microplasma as dynamic material in three dimensions, in combination of the isotropic geometry, provide the versatile abilities to control the electromagnetic responses including but not limited to photonic band gap. The details will be introduced in the conference.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123598659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study Of An Ultra-Fast Atmospheric Pressure Air Discharge In A Pin-To-Plate Geometry","authors":"J. Pouvesle, S. Iséni, S. Dozias, É. Robert","doi":"10.1109/PLASMA.2017.8496158","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496158","url":null,"abstract":"In this work, a pin-to-plate reactor operating in air at ambient temperature and pressure is investigated. Driven with a high-voltage (HV) ns pulse generator with sub-ns rise time excitation up to 50 kV, the discharge is ignited within a gap ranging from 0.5 to 25 mm. Although pin-to-plate discharges have been widely studied over the last century, the system offers the advantage to ignite the discharge in the over-voltage regime allowing for minimizing gas heating (at least in the single shot regime) and the production of highly energetic electrons due to the intense electric field (EF). As already shown, the discharge expends in very large and homogeneous volume (up to 20 mm diameter) within the gap. This is of high interest for atmospheric pressure volume treatment concerning either degradation of pollutants, assisted combustion ignition or activation of materials 1.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122117739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasma-Liquid Interaction For Treatment Of Hydraulic Fracturing Wastewater","authors":"J. Groele, J. Foster","doi":"10.1109/PLASMA.2017.8496056","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496056","url":null,"abstract":"Reactive species produced through plasma-liquid interaction is investigated for treatment of hydraulic fracturing wastewater. Unconventional shale gas and oil extraction has resulted in over 1.74 trillion liters of combined wastewater between 2005 and 2014, most of which has been injected into Class II disposal wells and removed from the water cycle 1. High total dissolved solid (TDS) concentrations that can exceed 260,000 mg/L limit the viability of contemporary treatment technologies due to intensive energy requirements and low throughputs, leading to the prominence of deep-well injection for wastewater management. Local water scarcity and seismic concerns motivate the need for a feasible treatment option that allows for wastewater recycling.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117180827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Studies on the Nonlinear Coupling in Atmospheric Dual Radio-Frequency Dielectric Barrier Discharge","authors":"Z. Zhang, Q. Nie, Z. Y. Wang, B. Jiang","doi":"10.1109/PLASMA.2017.8496196","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496196","url":null,"abstract":"Dielectric barrier discharges (DBD) as a common method to generate plasmas with high density, low gas temperature, and abundant active particle under atmospheric pressure have been widely investigated in the past decades. Among these researches, the investigation on plasma parameters modulation represents a novel and budding focus. According to our previous works of DBD driven by dual-frequency, it has been demonstrated to provide a possible approach of controlling both averaged electron density and gas temperature independently based on the nonlinear frequency coupling effect. In this work, we used one-dimensional fluid model with semi-kinetic method, systemically studied the nonlinear behavior of the dual radio-frequency driven DBD. In term of the results of effective electron energy distribution function (EEDF) and electron impact ionization rate, it is found that the variations of power density and phase relationship provide separate control over the electron density, mean electron energy and gas temperature. Moreover, mode transitions are discussed in this paper. It is shown that there exist three kinds of discharge modes, which are governed by the nonlinear dynamics in the plasma sheath. Among which, the ionization in α mode is determined by the nonlinear coupling electron heating and local momentary charge density. While in γ mode, the ionization is caused mainly by the electron avalanches. In summary, the dual radio-frequency applied in DBD system is found to generate a nonlinear synergistic effect between two frequencies, which can provide a possible approach to enhance control over the plasma parameters.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124028322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron Interactions With Plasma Feed Gases","authors":"Rakesh Bhavsar, Mohit Swadia, M. Vinodkumar, C. Limbachiya","doi":"10.1109/PLASMA.2017.8496265","DOIUrl":"https://doi.org/10.1109/PLASMA.2017.8496265","url":null,"abstract":"Major feed gases for plasma generation of F atoms are CF 4, SF 6 and NF 3. The etching process is determined by creation of F atoms through Dissociative Electron Attachment of CF 4 and by dissociation of CF 4 molecule through electronic excitation and ionization. Hence the estimation of excitation as well as ionization cross sections of e-molecule processes are required. Radicals of feed gases (CFx etc.) play important role in anisotropic etching. Also, restriction of emission of Perfluoro compunds and Global Warming Potential stimulates changes in feed gases. Therefore electron impact studies including computation of various cross sections and investigation of anion formation and resonances are major areas of interest. In this work we report various electron impact total cross sections, resonances and target properties for plasma feed gases and fluoro compounds over an extensive range of impact energies (0.1 eV - 5000 eV). Below 15 eV, we use ab-initio calculations with fixed nuclei approximation employing the molecular R-matrix method 1 and above the threshold of the target we employ the well-established Spherical Complex Optical Potential formalism 2.","PeriodicalId":145705,"journal":{"name":"2017 IEEE International Conference on Plasma Science (ICOPS)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129725321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}