2008 IEEE 35th International Conference on Plasma Science最新文献

{"title":"MHD simulation of conical plasma liners implosion","authors":"V. Gasilov, A. Boldarev, S. D'yatchenko, E. Kartasheva, O. Golkhovskaya, E. Grabovskiy, V. Alexandrov, I. Frolov, A. Gribov, A. Gritsuk, Y. Laukhin, S. Medovschikov, G. Volkov, K. Mitrofanov, G. Oleynik, A. Samokhin, V.I. Zayatsev, P. Sasorov, V. Smirnov","doi":"10.1109/PLASMA.2008.4591076","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591076","url":null,"abstract":"MHD numerical simulations are applied for multiparameter studies of quasi-spherical magnetic compression of plasma liners created by conical multiwire arrays electrical explosion at ANGARA-5-1 facility (TRINITI) with the discharge current 2 to 3 MA and the pulse rise time about 100 ns. The description of the plasma dynamics at different stages of implosion is reproduced as a result of simulation. Numerical and experimental time profiles of voltage drop at the load and soft X-ray yield power are compared. The effect of the geometry changes upon the implosion process is studied. Numerical simulation is based on 2D RMHD code MARPLE (IMM RAS) using unstructured triangular grids. The code implements one-fluid two-temperature MHD model, grid-characteristic method for radiative energy transfer and the model of prolonged plasma ablation to simulate plasma source. The governing MHD system of is completed by electrical equation for the full circuit including the generator itself, leading-in systems and the discharge chamber with the plasma in it. Equations of state, transport and kinetic coefficients, opacity and emissivity coefficients are taken from the tables. The behavior of the discharge is satisfactorily described in general by the above RMHD model. The plasma ablation model appeared to have a significant effect on both the entire scheme of plasma dynamics and such values as voltage drop at the load and soft X-ray yield power. The improvement of this model based on experimental and theoretical estimations is an issue of the day in 2D and 3D Z-pinch simulations. The MARPLE code calibrated against the conical liners simulations proved to be a useful tool for computations aimed to optimization of the experimental setup for 3D implosion of plasma.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74696404","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 collisional, capacitive RF sheath: models with and without the approximation of a sharp electron edge","authors":"R. Brinkmann","doi":"10.1109/PLASMA.2008.4590656","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590656","url":null,"abstract":"The transition from quasi-neutrality to charge depletion is one of the characteristic features of the plasma boundary sheath. For modeling purposes, this transition is often described in terms of the so-called step model which assumes a sharp transition point s (electron step) where the electron density ne drops from a value equal to the ion density ni (in the bulk, x>s) to a value of zero (in the sheath, x<s). Inserted into Poisson's equation, the step model yields an expression for the field which is realistic deep in the sheath but fails to merge correctly into the ambipolar field of the bulk. This work studies the consequences of that approximation for the example of the collision-dominated, capacitive RF sheath by Lieberman. The equations of the model combine an equation of continuity and a mobility ansatz for the ion fluid with the assumption of quasi-static Boltzmann equilibrium for the electrons and with Poisson's equation for the field. The modulation is controlled by the amplitude of the harmonic RF current. First, the model is solved exactly, using a relaxation scheme on a suitable spatio-temporal discretization. Then, the step approximation is applied which recovers Lieberman's semi-analytical solution. It is demonstrated that the step approximation induces a spurious divergence of the ion density at the sheath edge and prevents a matching of the sheath model to a bulk model. Integral sheath quantities, on the other hand, like the capacitance or the overall voltage drop, are faithfully reproduced, provided that the applied RF voltage is large compared to the thermal voltage Te/e. The consequences of this finding for the modeling of RF plasmas are discussed. Also studied is the performance of a recently proposed improved approximation of the Boltzmann-Poisson equation which treats the transition from quasi-neutrality to charge depletion more rigorously. It is shown that this approximation avoids the spurious divergence of the step model and leads to better agreement with the numerical solution.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74027343","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":"Bremmstrahlung target optimization for reflex triodes","authors":"S. Swanekamp, B. Weber, S. Stephanakis, D. Mosher","doi":"10.1063/1.2963090","DOIUrl":"https://doi.org/10.1063/1.2963090","url":null,"abstract":"Coupled particle-in-cell (PIC) and Monte Carlo simulations of the reflex triode have been performed with tantalum foil thicknesses varying between 2.5 mum (0.0056 times the CSDA range at 1 MeV) to 250 mum (0.56 the CSDA range at 1 MeV). The PIC/Monte Carlo simulations are in good agreement with reflex triode experiments on Gamble II at 1 MV, 1 MA. Experimental measurements and simulations both show that the dose is maximized for a foil thickness of about 20 mum. For foils thicker than 20 mum, the analysis shows that fewer of the 10-100 keV photons escape the foil reducing the dose. For foils thinner than 20 mum, the dose decrease is due to a loss of electron confinement to the foil allowing electrons to drift radially outward and strike a low-atomic-number foil holder which causes the dose to decrease. An examination of the electron orbits shows that for all foil thicknesses electrons initially flow radially inward under the influence of the strong self-magnetic field. If the foil is thick, then electrons lose a significant amount of energy with each interaction with the foil and are absorbed close to the point where they initially interact with the foil. If the foil is thin, electrons lose very little energy with each pass. For very thin foils, the simulations show that, with each pass, the electrons move outward in radius a distance of approximately twice the Larmor radius. Therefore, for thin foils, there are a limited number of passes the electrons can make before moving out of the diode where they strike the foil holder. Based on these results, a formula is derived that is able to predict fairly well the anode thickness that optimizes the dose.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74086837","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":"Simulation of Doppler reflectometry in turbulent plasmas","authors":"C. Lechte, U. Stroth, G. Conway","doi":"10.1109/PLASMA.2008.4591012","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591012","url":null,"abstract":"The absolute plasma density fluctuation strength and its dependence on the fluctuation wave number is determined using Doppler reflectometry as plasma diagnostic. Finite difference time domain code IPF-FD3D is used to investigate the dependence of the returned power from the various plasma conditions.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74112877","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":"Solenoidal transport of low-voltage (≤ 20 kV) sheet beams","authors":"J. Pasour, K. Nguyen, T. Antonsen, P. Larsen, B. Levush","doi":"10.1109/PLASMA.2008.4591040","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591040","url":null,"abstract":"This paper investigates solenoidal transport and show that it is not only feasible but preferred for certain types of devices. In particular, interest in low-voltage (<20 kV), high-power (~10 kW) W-band amplifiers has led to design an extended interaction klystron (EIK) that employs a solenoidal (~9 kG) transport configuration using permanent magnets. The much stronger magnetic field that can be achieved with a solenoidal magnet configuration allows significantly higher perveance beams to be transported, and simulations show excellent beam stability with essentially no current loss over distances of several diocotron growth lengths (typically several cm for millimeter-wave (MMW) device parameters). Semi-empirical scaling laws have been developed that relate the critical beam parameters (voltage, current density, emittance, and aspect ratio) and projected amplifier performance (power and efficiency) to the magnetic focusing strength. The implications of these relationships for the design of compact, low-voltage MMW amplifiers will be presented, and a permanent magnet solenoidal field configuration suitable for a MMW EIK will be described.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74116597","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":"Surface wave microplasma for localized etching","authors":"J. Narendra, J. Zhang, T. Grotjohn, N. Xi, J. Asmussen","doi":"10.1109/PLASMA.2008.4590733","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590733","url":null,"abstract":"A microwave re-entrant cavity is applied to create a miniature beam of plasma species. A miniature microwave plasma discharge is created using 2.45 GHz microwave energy to generate a discharge inside 1-2 mm inner diameter (i.d.) tubes with a micromachined aperture on the end. Through this aperture the plasma stream for materials processing is formed. The diameter of the plasma stream considered in this study ranges from 2 millimeters down to 10's microns. The I/V characteristics obtained from probe measurements show that the plasma ions pass through the aperture with a aperture hole diameter as small as 14 microns. Additional measurements of the microplasma generated in the discharge tube are performed to determine the electron temperature and gas temperature. Langmuir probe measurements give an electron temperature of approximately 2 eV when the pressure is in the range of 1 - 5 Torr. Optical emission spectroscopy measurements of argon/nitrogen discharge mixtures at 1 Torr in a 2 mm tube with 33 W microwave power give a temperature of 600K - 1200K dependent on the percent argon and nitrogen. The plasma discharge in the tube discharge region is modeled using both a global model and a surface wave discharge model. The flow of the plasma discharge/beam from the source, through the aperture, and down to the substrate surface is also modeled. The modeling results will be compared to experimental results for the size and shape of the region processed by the plasma discharge/beam. A CAD-guided automated path generation system is developed to assist manufacturing micro-structures/patterns automatically using the microplasma applicator. An argon/SF feed gas mixture is used to create a plasma stream with radicals for silicon etching. Also, the etching of Ultra- nanocrystalline Diamond (UNCD) is performed using an argon/oxygen plasma. Data will be reported on the etch results including etch rate and pattern profile for both gas chemistries.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74118813","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":"Theoretical and experimental study of an argon free burning arc dicharge at very high-pressure and low-intensity","authors":"E. Izquierdo, J. González-Aguilar, L. Fulcheri","doi":"10.1109/PLASMA.2008.4590715","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590715","url":null,"abstract":"This paper deals to study a low current intensity, very high-pressure (PGt105 Pa) free-burning argon arc discharge in a tip-tip configuration. A 2D axisymmetric two-temperature fluids model has been developed. The model contains three chemical species (e, Ar, Ar+), the appropriated thermodynamics and transport properties expressed as a function of electron and heavy temperatures and pressure, and the electrodes sheath submodel. Theoretical results were compared with experimental data obtained under pressure comprised between 0,1 to 10 MPa and 0.1 to 500 mA. Highest voltages are obtained at very high pressures and low current intensities. Theoretical model indicates that pressure increment causes an arc diameter reduction. This is due to the augmentation of radial heat losses by natural convection at arc fringes and by conduction due to a better energy transfer by neutral- electrons collisions. Surprisingly, the very high-pressure conditions seems having a stabilizing effect on the arc discharge.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79228345","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 xenon and tin discharge produced plasma EUV light source","authors":"M. Watanabe, N. Kishi, J. Yamada, O. Sakuchi, J. Fei, Zhu Qiushi, A. Okino, K. Horioka, E. Hotta","doi":"10.1109/PLASMA.2008.4590703","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590703","url":null,"abstract":"Recently, a lot of progresses have been made in the field of gas discharge and laser assisted extreme ultraviolet (EUV) light sources. In order to realize the EUV lithography, we have been developing the discharge produced plasma EUV light source with either Xe or Sn fuels. A Xe gas jet Z-pinch discharge system has been developed for generating high quality debris-free EUV emission. A 25kA pulsed power supply system has been constructed and introduced. Observation of optical characteristics are presently in progress. Also, the laser triggered discharge produced plasma with Sn electrode system has been constructed. In our system, after Nd-YAG laser was irradiated on Sn electrode surface for triggering the main discharge, EUV radiation will occur from the generated Sn plasma between electrodes and be collected radially. The maximum discharge current of about 6 kA with a pulse width of 500 ns was supplied to anode-cathode gap. In present study, EUV radiation emitted from gas jet Z- pinch Xe plasma and laser triggered Sn discharge produced plasma was quantitatively measured using an in-band calorimeter. Time-resolved in-band source image measurement was also conducted using a pinhole camera system.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84611010","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":"Atmospheric oxygen-helium plasma surface modification of medical plastics","authors":"P. Guschl, R. Hicks, S. MacDavid","doi":"10.1109/PLASMA.2008.4590932","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590932","url":null,"abstract":"This study examines the effect of atmospheric pressure plasma treatment on the surface energy and adhesive bond strength of three medical polymers: acetal copolymer (AC), polycarbonate (PC) and polyethylene terephthalate (PET). Surface treatments were applied with a two-inch plasma beam source and reactive oxygen-helium (~1-3 vol% O2) plasma under 150 and 200 W RF power. Through contact angle measurements and surface energy calculations, the response of these polymers to the plasma was found to be unique. Surface activation was rapid, occurring within 5 to 10 seconds of exposure. The PC and PET surface energies approached ges 70 dyne/cm. The acetal copolymer initially jumped to 58 dyne/cm, then declined with further plasma exposure, possibly due to etching or chain scission of the polymer. Langmuir-Hinshelwood reaction kinetics provided an excellent fit to the surface energy versus time data. Subsequent adhesion tests with epoxy, urethane and acrylate glues revealed large increases in adhesive bond strength for the AC (+50-300%), PC (+20-60%) and PET (+100-350%) following exposure times of 0.25 to 40 s under the plasma beam. At the meeting, I will describe the mechanism for activation of the polymer chains with the atmospheric pressure oxygen plasma.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84958721","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":"Temporal and spatial evolution of carbon ion beam emission in plasma focus discharges","authors":"A. Henriquez, H. Bhuyan, M. Favre, H. Chuaqui, E. Wyndham","doi":"10.1109/PLASMA.2008.4590965","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590965","url":null,"abstract":"Summary form only given. In plasma focus (PF) a high density, high temperature, short duration Z-pinch like plasma column is formed, following a radial compression phase. The PF is a well known source of energetic ion beams, of characteristic energy from hundreds of keV to tens of MeV. Several theoretical and computational models have been developed in an attempt to explain the ion production and acceleration mechanism in PF discharges. Despite this theoretical effort, a complete explanation of the ion emission mechanism is still not available. We have performed a detailed investigation on the time evolution and angular distribution of PF ion beams. We have previously characterized the main features of ion beam emission in a low energy, 1.8 kJ, 160 kA Mather type PF device, operating in methane. In the present investigation axial and radial biased Faraday cup ion probes, which are also sensitive to XUV radiation, were used simultaneously in conjunction with a radial X-ray detector to correlate the ion beam emission with the different stages in the PF dynamics. We have observed that the ion beams emitted radially are mostly associated with the radial compression phase of the PF discharge, prior to the formation of a Z-pinch like plasma column. At this stage the ion beams composition is dominated by C+2 ions. At later times, around the maximum compression phase, the axial emission becomes dominant and the ion beam composition is found to be mainly C+4 and C+5 ions. In general, the axial ion beam emission is found to be of much higher characteristic energy and flux than the radial emission. These results indicate that no unique mechanism for ion beam emission in PF can be assumed. Based on the time correlations and measured properties of the ion beams, the plasma conditions at the time of the different stages in the ion emission will be discussed, in order to assess the validity of current PF ion beam emission models, which account for different properties of the beams, such as characteristic energy scaling and angular distribution.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85025768","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}