2016 IEEE International Conference on Plasma Science (ICOPS)最新文献

{"title":"Effects of electron beam focusing on virtual cathode formation in virtual cathode oscillator","authors":"Se-Hoon Kim, Chang-Jin Lee, J. Rhee, Young-Maan Cho, Ji-Eun Baek, K. Ko","doi":"10.1109/PLASMA.2016.7533984","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7533984","url":null,"abstract":"As a high power microwave (HPM) source, virtual cathode oscillator has been studied due to its simplicity. A lot of experiments on virtual cathode oscillator has been conducted and reported to study the characteristics and to increase its efficiency. In order to increase its efficiency, ballistic focusing of an electron diode has been studied. And it is reported that the efficiency of virtual cathode oscillator is somewhat increased through the ballistic focusing.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"518 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133226577","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":"Role of ionization dynamics on copper ion acceleration driven by intense short pulse laser and ultra-thin film interaction","authors":"Jinqing Yu, C. McGuffey, F. Beg","doi":"10.1109/PLASMA.2016.7534171","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534171","url":null,"abstract":"Summary form only given. Acceleration of copper ions from ultra-thin targets by a short pulse laser (30fs) with intensity of 10²⁰ W/cm² were systematically studied using two-dimensional relativistic Particle-in-Cell code EPOCH2D¹, which includes an ionization module. It was found that ionization dynamics play an important role in heavy ion acceleration, particularly in the generation of quasi-mono-energetic ion bunches. These bunches were generated from the both sides of target and accelerated by the sheath fields on the surfaces, being attributed from ionization dynamics and Target Normal Sheath Acceleration (TNSA)^2,3. In study of 20 nm copper target, higher charge state ions Cu⁺²⁶ and Cu⁺²⁷ were generated by the laser pulse directly from the target front side. On the target rear side, we detected quasi-mono-energetic Cu⁺²⁰, Cu⁺²¹, Cu⁺²², Cu⁺²³, Cu⁺²⁴ and Cu⁺²⁵ ion bunches. The peak energy increased with ion charge number from 82 MeV (Cu⁺²⁰) to 157 MeV (Cu⁺²³), and the particle number was around 4.5×10⁸ ~ 7×10⁸ for each ion species. A scan of target thickness was made to find an optimum thickness for ion acceleration for the given laser parameters, which was 10 nm. The effect of impurities was also considered in which quasi-mono-energetic O⁺⁷ and O⁺⁸ ion bunches were obtained with O⁺⁸ bunches accelerated to a peak energy of 85 MeV. In this work, it is clear that much more information of ions was obtained than normal PIC simulations, which further helped us to understand the whole interaction process to improve ion acceleration experimental design.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115550600","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":"Experiments on electrothermal instability as a seed for Magneto-Rayleigh-Taylor instability on accelerating, ablating foils","authors":"A. Steiner, D. Yager-Elorriaga, P. Campbell, S. Patel, N. Jordan, Y. Lau, R. Gilgenbach","doi":"10.1109/PLASMA.2016.7534281","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534281","url":null,"abstract":"Summary form only given. The electrothermal instability (ETI) arises whenever a current-carrying material has a resistivity that depends on temperature. When resistivity, η, increases with increasing temperature, ETI causes striations to form perpendicular to the direction of current. On pulsed-power-driven, ablating metallic loads, this process can cause sections of the target to ablate earlier than the bulk material, creating a macroscopic surface perturbation on the plasma-vacuum interface. Experiments are underway on the MAIZE 1-MA linear transformer driver at the University of Michigan to study surface perturbations produced by ETI as seeding for the Rayleigh-Taylor (MRT) instability on imploding liner [1] and accelerating foil plasmas [2]. Target foils are fabricated at the Lurie Nanofabrication Facility at UM by depositing ultrathin (200 to 500 nm) coatings of aluminum or titanium on 1.5 μm Chemplex Ultra-Polyester films. Foil thicknesses are chosen to maintain the same mass between shots, and the materials are chosen to provide substantially different values of dη/dt, which impacts the growth rate of the electrothermal instability. Targets are ablated and accelerated by driving a current of 500 to 600 kA on MAIZE, and the accelerated plasmas are imaged using a 12-frame laser imaging system. Images of these plasmas are compared to determine if initial plasma interface perturbations are measurably different on targets of different materials, with the same mass, but different ETI growth rates.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115563023","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":"Realistic surface reaction modeling for 3D feature profile simulation of fluorocarbon-based plasma etch process","authors":"Yeong-Geun Yook, H. S. You, Y. Im, Won-Seok Chang","doi":"10.1109/PLASMA.2016.7534064","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534064","url":null,"abstract":"Summary form only given. One of the emerging challenges in next generation device is to achieve the high aspect ratio contact holes using fluorocarbon plasma. However, it is regarded that the predictable simulation for these processes is beyond current science and technology due to their inherent complexity of fluorocarbon plasma. To address these issues, we have developed a realistic and ultrafast 3D topography simulator of semiconductor plasma processing coupled with zero-D bulk plasma models. In this work, we introduce a surface reaction model to capture the realistic surface reaction phenomena under the fluorocarbon plasma. This surface reaction model is based on a two-layer model that considers plasma etch kinetics at a mixed layer of fluorocarbon and target material under the existence of a steady-state fluorocarbon passivation layer during plasma etching. The key parameters in this surface reaction model are extracted by previously reported data or fitting experimental data from several diagnostic tools in a fluorocarbon plasma system. Based on this model, useful information such as the thickness of polymer passivation layer, and deposition/etch rate can be obtained by functions of the incidence ion energy, neutral and ion fluxes. Finally, we demonstrate that 3D feature profile simulation coupled with this realistic surface reaction model can lead to better understanding of the emerging issues in plasma etch process, such as necking, bowing, etch stops and twisting during high aspect ratio contact hole etch in semiconductor plasma process.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"9 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124278616","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":"Optical emission spectroscopy of dielectric barrier discharges with multiple current peaks","authors":"V. P. Boudriau, L. Stafford","doi":"10.1109/PLASMA.2016.7533975","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7533975","url":null,"abstract":"Summary form only given. Dielectric barrier discharges (DBDs) at atmospheric pressure can be operated in either filamentary or homogenous regime. The former is characterized by many short and erratic current pulses while the latter has a broad and well-defined current peak per half-cycle of the applied sinusoidal voltage. In selected conditions, homogeneous discharges can exhibit more than one current peak. However, the physics driving such multiple current peak discharges remains unexplored. In this work, time-resolved optical emission spectroscopy (OES) is used analyze the time evolution of the plasma characteristics and discharge regime in DBD operated in nominally pure He (3 SLPM, UHP grade). As described previously, the discharge was sustained in a plane-to-plane configuration (1 mm gap between the two alumina dielectric plates), with a sinusoidal applied voltage of either 1.3 or 2.5 kV peak-to-peak, and a frequencies of either 6 or 12 kHz. In addition to the expected emission lines from the He I n=3 levels (triplet and singlet states), OES spectra recorded from He2 (bandhead at 640 nm) as well as from Ar I (750.4 nm, bottle impurity). All He n=3 lines sharply rose before the current peaks and then decreased before the discharge current reached maximum values. On the other hand, for Ar I, maximum line intensities were observed after the discharge current peaks maxima. Over the range of experimental conditions investigated, Ar I excited states are mostly populated by Penning reactions with He metastable atoms such that their time behaviors corresponds to the evolution of the population of He n=2 states (in relative units). This set of data along with all He n=3 line intensities were coupled to the predictions of a collisional-radiative model using the electron temperature Te (assuming Maxwellian electron energy distribution function) as the only adjustable parameter. For single current peak discharges, Te decreased from about 1 eV early in the discharge cycle to 0.2 eV at the current maximum (and during discharge extinction). Such decrease of Te with increasing discharge current is ascribed to the Townsend-to-glow transition. In presence of additional current peaks, only small rises in Te values were observed, indicating that the discharge remains in glow mode.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114584970","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":"Enhancement of betatron x-rays in a laser plasma accelerator","authors":"Liming Chen","doi":"10.1109/PLASMA.2016.7534321","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534321","url":null,"abstract":"Summary form only given. Betatron radiation is a highly collimated laser-driven hard x-ray source with fs duration which generated by electron transversely oscillation during acceleration in underdense plasmas. We will present our recent progress in enhancing acceleration to optimize the x-ray photon yield/energy. 1) A new method is demonstrated for generating intense betatron x-rays using a clustering gas target [ 1]. The yield of the Ar x-ray betatron emission has been measured to be 2x108 photons/pulse. Simulations point to the existence of clustering as a contributor to the DLA mechanism, leading to higher accelerated electron charge (x40) and much larger electron wiggling (-8 μm) amplitudes in the plasma channel, thereby finally enhancing the betatron x-ray photons. 2) Another concept of generation of bright betatron radiation during electron acceleration was newly invented [2]. Two electron bunches were injected sequentially into the wakefield. The first one is a mono-energetic electron bunch with energy of GeV level, and the second one is injected continuously with large charge and performs resonantly transverse oscillation with large amplitude during the subsequent acceleration, which results in the enhancement of betatron x-ray emission. After optimize interaction conditions, Gamma-rays with yield reaches to 10 11 can be obtained by using 200TW laser [3]. 3) In order to control the stability of betatron x-ray generation as well as enhance its yield and energy, ionization injection with N2 gas is studied. In experiment, we obtained stably accelerated monoenergetic electron beams with energy spread 5% only for the first time [4]. 109 photons in hard xrays and 108 photons in gamma-rays are stimulated, results in a peak brightness 1023 phs/s/mm2/mrad2/(0. 1%BW). Quick injection, acceleration and oscillation in the wake of the ionization injected electron leads to the effective resonant betatron oscillation, which result in gamma -ray photon energy and peak brilliance beyond that of 3rd generation synchrotron facilities [5].","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114997416","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":"Analysis on the discharge process of a particle beam triggered gas switch","authors":"W. Tie, Lixue Zhou, Y. Zhang, Q. Zhang, R. Han","doi":"10.1109/PLASMA.2016.7534041","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534041","url":null,"abstract":"Summary form only given. A transient optical diagnostic system for studying the discharge characteristics of a particle beam triggered gas switch was built, so that the temporal and spatial evolution of particle beam was observed in real time and the velocity curves of particle beam under different gas pressures were obtained. And the discharge processes of two spark gaps were photoelectric diagnosed and analyzed respectively. The results showed that, the particle beam moved forward in a bullet mode, and the speed of which increased with the decrease of pressure and decreased with time growing. At the initial time, the speed of the particle beam could reach 3.68×106cm/s. The positive and negative streamers were occurred in the triggered gap and particle-beam gap respectively. At the lowest working coefficient 47.2%, the delay time of the two gaps was 34.2ns and 42.1ns, which were basically same as optical diagnostic results. The particle beam triggering was a non-penetrating induced discharge method, and the electric field of the head of discharge channel was enhanced through injecting electrons to the spark gap. The discharge process was accelerated from electron avalanche to streamer, and it was conducive to the rapid closure of the switch.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123501512","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":"Isolated, high voltage arbirtary pulse generator","authors":"K. Miller, T. Ziemba, J. Prager, I. Slobodov, J. Picard","doi":"10.1109/PLASMA.2016.7534028","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534028","url":null,"abstract":"Eagle Harbor Technologies, Inc. has developed an Arbitrary Pulse Generator (APG) with isolated high voltage output. The EHT APG can produce output pulses with voltages up to 10 kV and fast rise time (100 ns) at high pulse repetition frequency (up to 100 kHz) with a user-adjustable duty cycle from 0-100%. The isolated output allows the pulse generator to be connected to loads that need to be biased. These pulser generators utilize modern silicon carbide (SiC) MOSFETs, which offer lower switching and conduction losses while allowing for higher switching frequency capabilities compared to IGBTs. This pulse generator has applications for RF plasma heating; inductive and arc plasma sources; magnetron driving; and generation of arbitrary pulses at high voltage, high current, and high pulse repetition frequency in the semiconductor processing, non-equilibrium plasma source, and material processing communities.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125990082","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":"Recent advances in theory and experiment of metamaterial-based high power radiation sources","authors":"Z. Duan, Yanshuai Wang, Xianfeng Tang, Zhanliang Wang, Y. Gong","doi":"10.1109/PLASMA.2016.7534379","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534379","url":null,"abstract":"Metamaterials are artificial materials engineered to have properties that have not yet been found in nature such as reversed Cherenkov radiation (RCR). Currently, research in metamaterials is turning from theory to application exploration. The emerging metamaterials bring new developing opportunities in the conventional high power microwaves and vacuum electronics due to the exotic properties such as miniaturization, high power and high efficiency1. In this talk, two kinds of new all-metal metamaterials are briefly introduced. Thus the novel slow-wave structures are proposed based on the metamaterials and metal waveguides operating the cut-off frequencies, which is quite different from the normal case2, 3. And then we have studied the high frequency characteristics such as dispersion, interaction impedance, and transmission and reflection properties through simulation and “cold” experiment. Finally, two metamaterials-based high power radiation sources with a sheet beam and a traditional pencil beam have been studied by PIC simulations, respectively. For the sheet beam device, the peak output power is 1.5 MW at 2.90 GHz and electronic efficiency is 12.5%. For the pencil beam device, the peak output power is 4 MW at 2.454 GHz and electronic efficiency is 31.5%. In the near future, the “hot” experiments will be done.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125000707","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":"Migration of multipactor trajectories via higher-order mode perturbations","authors":"S. Rice, J. Verboncoeur","doi":"10.1109/PLASMA.2016.7534360","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534360","url":null,"abstract":"Multipactor1,2 is a resonant phenomenon in which an electromagnetic field causes a free electron to impact a surface, resulting in the surface emitting one or more secondary electrons. If the surface geometry and electromagnetic fields are appropriately arranged, the secondary electrons can then be accelerated and again impact a surface in the bounding geometry. If the net number of secondary electrons participating in multipactor is non-decreasing, then the process can repeat indefinitely. This phenomenon is of considerable practical interest in the design and operation of radio frequency (RF) resonant structures, windows, and supporting structures.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"1809 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129689292","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}