2007 IEEE 34th International Conference on Plasma Science (ICOPS)最新文献_第6页

Avalanche Injection and Lock-On in Photoconductive Semiconductor Switches 光导半导体开关中的雪崩注入和锁定

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345660

H. Hjalmarson, K. Kambour, C. Myles, R. Joshi

{"title":"Avalanche Injection and Lock-On in Photoconductive Semiconductor Switches","authors":"H. Hjalmarson, K. Kambour, C. Myles, R. Joshi","doi":"10.1109/PPPS.2007.4345660","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4345660","url":null,"abstract":"Optically-triggered, high-power photoconductive semiconductor switches (PCSS's) composed of semi-insulating GaAs carry current in high carrier-density filaments after the optical trigger is discontinued. This highly conductive mode of operation is called lock-on. The properties of these filaments can be explained by collective impact ionization theory in which energy redistribution by carrier-carrier scattering within the filament enhances the impact ionization rate. This allows these filaments to be sustained by fields which are relatively low compared to the bulk breakdown fields. For GaAs, the sustaining lock-on field is approximately 4.5 kV/cm. For this talk, a hydrodynamic implementation of the collective impact ionization theory is used to compute the temporal evolution of these filaments following optical triggering. These continuum calculations are based on previous calculations in which the steady-state properties of filaments are computed using a Monte Carlo method to solve the Boltzmann equation. The same method will be used to calculated avalanche injection effects in a GaAs avalanche photodiode. The two modes of operation, lock-on and avalanche, will be compared and contrasted. In addition, the effects of carrier recombination at defects will also be discussed.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132975592","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}

引用次数: 0

Numerical Simulation of Beam Interaction with Plasma and Gas in Diodes for Flash X-Ray Radiography 闪烁x射线照相二极管中光束与等离子体和气体相互作用的数值模拟

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345847

I. V. Glazyrin, A. V. Karpeev, Y. Kandiev, O. G. Kotova, D. Modestov, V. Plokhoi, S. N. Shcherbakova, E.Yu. Smirnov

{"title":"Numerical Simulation of Beam Interaction with Plasma and Gas in Diodes for Flash X-Ray Radiography","authors":"I. V. Glazyrin, A. V. Karpeev, Y. Kandiev, O. G. Kotova, D. Modestov, V. Plokhoi, S. N. Shcherbakova, E.Yu. Smirnov","doi":"10.1109/PPPS.2007.4345847","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4345847","url":null,"abstract":"Summary form only given. A number of questions should be solved in the course of development of new diodes for radiographic applications. (1) In self magnetically pinched diodes plasma near electrodes can significantly affect electron beam focusing and Bremsstrahlung formation. (2) It is necessary to know the influence of angle spread and initial rotation of electron beam on focusing properties. (3) If gas-filled focusing cell is used, the result depends on choice of gas density. To answer the above questions PICNIC hybrid code was developed, which consists of several interrelated parts: 2D PIC code calculating dynamics of relativistic particles (electrons and ions), 3D FDTD solver for Maxwell equations, 2D MHD description for thermal electrons and ions, Monte-Carlo code PPJZMA defining particles momentum and angle after collisions. For the calculation of magnetic field the current through the anode surface is accounted. Generator parameters were the next. Diode with gas-filled focusing cell is analyzed for generator with parameters: 5 MV voltage with 30 kA current. For self-magnetically pinched diode the generator used 10.0 MV, 200 kA, 50 nsec FWHM electric pulse.Calculation results show, that diodes operate in different regimes depending on current value: initially quasi-uniform beam motion in vacuum, then unstable motion of high-current electron beam in plasma. Return current and magnitudes of local current densities inside plasma play an important role in these collective effects of beam-plasma interactions. These processes significantly depend on beam initial parameters, spread of angle velocities and energies. For rod-pinch diode incidence angles of electrons during Bremsstrahlung generation may vary in 50deg.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132643190","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}

引用次数: 0

Flash X-Ray Diffraction System for Ultrafast Temperature and Phase Transition Measurements 用于超快温度和相变测量的闪光x射线衍射系统

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345546

D. Morgan, D. Macy, M. Madlener, J. Morgan

{"title":"Flash X-Ray Diffraction System for Ultrafast Temperature and Phase Transition Measurements","authors":"D. Morgan, D. Macy, M. Madlener, J. Morgan","doi":"10.1109/PPPS.2007.4345546","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4345546","url":null,"abstract":"A novel ultrafast diagnostic for determining bulk temperature and phase transitions for polycrystalline metal objects has been developed. The diagnostic consists of a 38-stage Marx bank with a cable-coupled X-ray diode that produces a 35-ns pulse of mostly 0.71 Angstrom monochromatic X rays, and a P-43 fluor coupled to a cooled charge-coupled device camera by a coherent fiber-optic bundle for detection of scattered X rays. The X-ray beam is collimated to a 1deg divergence in the scattering plane with the combination of a 1.5-mm tungsten pinhole and a 1.5-mm diameter molybdenum anode. The X-ray diode, in a needle-and-washer configuration, is heavily shielded in all directions other than the collimated beam. The X-ray diode has a sealed reentrant system, which allows the X rays to be produced inside a vacuum containment vessel, close to the sample under study. The direct correlation between the solid-state structure and the coherent X-ray diffraction pattern from a metal surface allows an unequivocal determination of a phase transition. This correlation has been tested in the laboratory with samples of indium and tin. For both metals, diffraction lines were observed at temperatures just below the melt temperature, along with background consisting of Compton scattering and sample fluorescence. Upon melt, the diffraction lines were observed to disappear; however, the background from Compton scattering and sample fluorescence remained. Flash X-ray diffraction also enables direct ultrafast measurements of the bulk temperature of the sample under study. According to the Debye-Waller theory, the diffracted line intensity reduces as the temperature of the sample increases. The amplitude of the reduced diffracted signal also depends on the Debye temperature of the sample, the scattering angle of the diffracted X rays, and the X-ray wavelength. The feasibility of using the Debye-Waller theory for flash X-ray diffraction measurements of the bulk temperature is currently being studied.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131103346","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}

引用次数: 0

Bioactivity and Corrosion Resistance of NiTi After Calcium Plasma Immersion Ion Implantation 钙等离子体浸泡离子注入后NiTi的生物活性和耐蚀性

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345830

X. Liu, S. Wu, P. Chu, Y. Chan, C. Chung, C. Chu, K. Yeung, W. Lu, K. Cheung, K. Luk

{"title":"Bioactivity and Corrosion Resistance of NiTi After Calcium Plasma Immersion Ion Implantation","authors":"X. Liu, S. Wu, P. Chu, Y. Chan, C. Chung, C. Chu, K. Yeung, W. Lu, K. Cheung, K. Luk","doi":"10.1109/PPPS.2007.4345830","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4345830","url":null,"abstract":"Summary form only given. Plasma immersion ion implantation (PHI) is an effective approach to enhance the surface properties of various types of biomaterials. In order to enhance the surface bioactivity and corrosion resistance of NiTi shape memory alloy, calcium ions were implanted into NiTi alloys that have been pre-plasma-implanted with oxygen and nitrogen. The results are compared to samples without pre-treatment. The bioactivity of calcium-implanted NiTi was evaluated by immersion tests in simulated body fluid (SBF). The surface of NiTi before and after immersion tests was characterized by X-ray photoelectron spectroscopy (XPS). The XPS results reveal that the structure of the calcium-implanted layer in all the samples is composed of calcium oxide and gradually becomes a Ca-P layer after a period incubation in SBF. This Ca-P film also can be detected by scanning electron microscopy (SEM). To evaluate the anti-corrosion performance of NiTi, electrochemical potentiodynamic polarization tests were conducted on the NiTi samples in SBF. NiTi samples with pre-oxygen and nitrogen plasma implantation exhibit better corrosion resistance than single calcium-implanted samples. Our results indicate that calcium implantation can enhance the bioactivity of NiTi alloy due to the formation of calcium phosphate on the surface of the alloy. Plasma ion implantation can also improve the corrosion resistance of NiTi.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133496748","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}

引用次数: 0

A Compact Fast Marx Generator with Repetition Rate 10Hz 紧凑型快速马克思发生器，重复频率10Hz

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345517

W. Xie, H. Liu, H. Li, W. Dai, J. Den

引用次数: 0

Two-Dimensional Collisionless Weakly-Ionized Plama in Fluid Approximation

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345591

V. Ciodyak, N. Sternberg

{"title":"Two-Dimensional Collisionless Weakly-Ionized Plama in Fluid Approximation","authors":"V. Ciodyak, N. Sternberg","doi":"10.1109/PPPS.2007.4345591","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4345591","url":null,"abstract":"Summary form only given. In laboratories and various applications, plasmas are always multidimensional. In basic research experiments and in the majority of plasma processing reactors, the finite plasma cylinder is the most common plasma shape. In the diffusion limit described by the Schottky model, the two-dimensional plasma density profile for a finite cylinder of length 2L and diameter 2R is the product of the corresponding one-dimensional solutions, namely, n(x,r)/n0 = cos(pix/2L) . J0(2.4r/R). Because of this, even when the Schottky model is not applicable (such as in the cases of collisionless ions, or variable ion mobility), the representation of the plasma spatial distribution by the product of the corresponding one-dimensional solutions has remained a common approach at low gas pressures. In this presentation, numerical solutions for the two-dimensional fluid model of a collisionless weakly-ionized plasma cylinder for arbitrary aspect ratios L/R will be demonstrated. The behavior of the ionization frequency, plasma densities at the radial and axial boundaries, the spatial plasma profile, the plasma flux, as well as the entering angle of ions at the plasma boundary for a wide range of the aspect ratio will be analyzed. The obtained results w ill show that for cylindrical collisionless plasma, the spatial plasma profile cannot be represented by the product of the corresponding one-dimensional solutions. Moreover, in the limiting cases of small and large aspect ratios, the plasma distribution along the longer length (L or R) approaches the diffusion distribution, which corresponds to the highly collisional ion motion, although the ion motion in this direction is collisionless.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127603552","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}

引用次数: 0

No Removal by NS Pulsed Streamer Discharge NS脉冲流光放电不去除

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345630

T. Tokuichi, D. Wang, T. Namihira, S. Katsuki, H. Akiyama

{"title":"No Removal by NS Pulsed Streamer Discharge","authors":"T. Tokuichi, D. Wang, T. Namihira, S. Katsuki, H. Akiyama","doi":"10.1109/PPPS.2007.4345630","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4345630","url":null,"abstract":"Summary form only given. The conventional methods such as SCR method, Electron Beam method and Lime-gypsum method could not treat exhaust gases completely. In addition, the energy efficiency and the cost in the conventional ways are still negative situation. In recent years, the pollution control techniques using electric discharge plasmas which could attract attention as the low cost and high energy efficient exhaust gas treatment method, have been widely studied. In our laboratory, pulsed streamer discharge plasmas which are one of the non-thermal plasmas have been used to treat exhaust gases. Since a pulse width of applied voltage has a strong influence on the energy efficiency of the removal of pollutants, the development of a short pulse generator is of paramount importance for practical applications. In this work, ns pulse generator which can output the 5ns pulsed voltage is developed. Furthermore, the NO removal experiment is conducted using the ns pulse generator. As the results, the ns pulsed discharge has an advantage in energy efficiency for NO removal in comparison with sub-mus pulsed discharge. As the characteristics of NO removal using the ns pulsed streamer discharge, the polarity of and the amplitude of applied voltage to the reactor have significant influences on the improvement of energy efficiency of NO removal. On the other hands, it is clear that the longer length of and the smaller diameter of the coaxial discharge reactor give the higher energy efficiency. The maximum energy efficiency of NO removal by ns pulsed streamer discharges reaches 1.5 mol/kWh at 60% of NO removal ratio.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131639862","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}

引用次数: 3

Pulsed Corona in Water: Pulse Generation and Applications 水中脉冲电晕:脉冲的产生和应用

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4345645

W. Hartmann, M. Roemheld, K. Rohde, F. Spieß

{"title":"Pulsed Corona in Water: Pulse Generation and Applications","authors":"W. Hartmann, M. Roemheld, K. Rohde, F. Spieß","doi":"10.1109/PPPS.2007.4345645","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4345645","url":null,"abstract":"Summary form only given. Removal of organic pollution from water is of increasing concern for drinking water as well as for many industrial processes. Application of pulsed corona discharges is a known possibility to attack that problem by producing highly active radicals in-situ, without using additional chemistry. To investigate the efficiency of submerged pulsed corona discharges in water we have built a laboratory scale, parallel-plate, flow-type reactor that is part of a closed loop water circulation system. A pulsed voltage is applied across the electrodes. One of the electrodes is coated with a porous ceramic layer in order to create local field enhancements to initiate corona discharges. For energisation of the plasma reactor a pulse generator has been developed which is based on a capacitor discharge initiated by a semiconductor switch. A pulse transformer, followed by two magnetic pulse compression stages, produces voltage pulses with amplitudes of up to 37 kV at a pulse width of 0.3 mus. Simulation of the circuit behavior leads to good agreement with voltage and current measurements. Details of the pulse generator and first experimental results concerning the efficiency of radicals production are presented. Depending on the conductivity of the water to be treated, pulse currents of > 600 A at a voltage of 37 kV are obtained for electrode sizes of around 50 cm2. The efficiency of the radical production is measured in terms of the hydrogen peroxide (H2O2) concentration, which is formed by recombination of hydroxyl radicals (OH) at sufficiently high concentrations downstream of the plasma reactor. At pulse repetition rates of 20 to 100 Hz, H2O2 concentrations of up to several mg/l are produced. Production efficiencies have been measured to be in the range of up to ap1 g/kWh.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115378633","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}

引用次数: 0

Effect of Attenuation in Synchronous and Non-Synchronous Beam-Wave Interactions 同步与非同步波束波相互作用中的衰减效应

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4346010

D. Dialetis, D. Chernin, T. Antonsen, B. Levush

{"title":"Effect of Attenuation in Synchronous and Non-Synchronous Beam-Wave Interactions","authors":"D. Dialetis, D. Chernin, T. Antonsen, B. Levush","doi":"10.1109/PPPS.2007.4346010","DOIUrl":"https://doi.org/10.1109/PPPS.2007.4346010","url":null,"abstract":"Summary form only given. The gain of a traveling wave tube, in which the beam velocity is closely matched to the phase velocity of a slow circuit wave, decreases as the circuit loss increases. However, sufficiently far from synchronism an increase in circuit loss will cause an increase in gain - a phenomenon well known as the resistive wall instability. Between these extremes there are parameter regimes in which the gain is relatively insensitive to loss. A careful analytical study of a beam interacting with the slow wave fields propagating on a sheath helix, itself supported by a lossy dielectric sleeve, illustrates these effects. The central goal of this study is to determine whether the approximate treatment of circuit attenuation in the CHRISTINE ID large signal helix TWT simulation code is sufficiently accurate for the largest values of attenuation encountered in TWTs (in and near severs), for all operating voltages. Our approach has been to develop an exact small signal theory and associated code for the analysis of a beam interacting with a slow wave supported by a sheath helix. In this paper we will describe the approximate model for attenuation used in CHRISTINE as well as the exact ID small signal model. Numerical results from both models and comparisons using a C-band helix TWT will be presented.","PeriodicalId":446230,"journal":{"name":"2007 IEEE 34th International Conference on Plasma Science (ICOPS)","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115531070","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}

引用次数: 0

Influence of Resistance of Electric Arc on Transients Due to Disconnector Switching in Air-Insulated Substations 空气绝缘变电站隔离开关电弧电阻对暂态的影响

2007 IEEE 34th International Conference on Plasma Science (ICOPS) Pub Date : 2007-06-17 DOI: 10.1109/PPPS.2007.4652549

S. Carsimamovie, Z. Bajramovic, M. Veledar, M. Ljevak, A. Carsimamovic, P. Osmokrović

引用次数: 1