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Sample records for plasma electron temperature

  1. Theoretical determination of electron temperature in electron-cyclotron plasmas

    SciTech Connect

    Uhm, H.S.; Lee, P.H.; Kim, Y.I.; Kim, J.H.; Chang, H.Y.

    1995-12-31

    A basic theory of the plasma electron temperature in ECR plasmas has been reported in recent studies in connection with application to the plasma etching technologies. However, the previous theoretical study of the ECR plasmas is primitive and ad hoc. The authors therefore develop a theory for plasmas generated by the electron-cyclotron-resonance (ECR) mechanism and an experiment is conducted to compare the theoretical prediction and experimental measurements. Due to a large electron mobility along the magnetic field, electrons move quickly out of the system, leaving ions behind and building a space charge potential, which leads to the ambipolar diffusion of ions. In a steady-state condition, the plasma generation by ionization of neutral molecules is in balance with plasma loss due to the diffusion, leading to the electron temperature equation, which is expressed in terms of the plasma size, chamber pressure, and the ionization energy and cross section of neutrals. The electron temperature decreases as the chamber pressure increases. Based on the ambipolar diffusion of ions, a self-consistent theory of the plasma density profile is developed. The power balance condition leads to the plasma density equation, which is also expressed in terms of the electron temperature, the input microwave power and the chamber pressure. It is shown that the plasma density increases, reaches its peak and decreases, as the chamber pressure increases from a small value (0.1 mTorr). After carrying out an experimental observation, it is concluded that the theoretical predictions of the electron temperature and plasma density agree remarkably well with experimental data.

  2. Electron temperature dynamics of TEXTOR plasmas

    NASA Astrophysics Data System (ADS)

    Udintsev, Victor Sergeevich

    2003-11-01

    To study plasma properties in the presence of large and small MHD modes, new high-resolution ECE diagnostics have been installed at TEXTOR tokamak, and some of the already existing systems have been upgraded. Two models for the plasma transport properties inside large m/n = 2/1 MHD islands have been found to give estimations for the heat diffusivities, which are much lower than the global plasma heat diffusivity, which is in agreement with previous measurements in different tokamaks. The 3D-reconstruction of large m/n = 2/1 modes in TEXTOR with the help of all available ECE diagnostics allows modelling the island as a structure with closed flux surfaces. The main plasma heat flux flows through the X-point area probably along stochastic magnetic field lines. The confinement is improved within the magnetic island, compared to the background plasma. This is confirmed by a temperature profile flattening and sometimes even a secondary peaking inside the island, compared to the X-point. Making use of the mode rotation, assumed to be a rigid rotor, it has been possible to obtain information on the topology of the m = 1 precursor mode leading to sawtooth collapses. It becomes clear that this precursor cannot be described by an m = 1 cold tearing mode island but by a hot crescent wrapped around a cold high-density bubble. In the future multi-chord ECE-imaging will allow this mode reconstruction without the assumption of the rotation to be rigid. From the measurements of the broadband temperature and density fluctuations one can conclude that the turbulent structures inside the q = 1 surface are separated from the turbulence outside the q = 1 surface. This fits nicely with the observation that q = 1 surface acts as a barrier for the thermal transport. Correlation length and time measured inside q = 1 are in agreement with the observed turbulent heat diffusivity. Qualitative studies of non-thermal electrons at different heating regimes (ECRH and Ohmic) at TEXTOR were done

  3. A simple model for electron temperature in dilute plasma flows

    NASA Astrophysics Data System (ADS)

    Cai, Chunpei; Cooke, David L.

    2016-10-01

    In this short note, we present some work on investigating electron temperatures and potentials in steady dilute plasma flows. The analysis is based on the detailed fluid model for electrons. Ionizations, normalized electron number density gradients, and magnetic fields are neglected. The transport properties are assumed as local constants. With these treatments, the partial differential equation for electron temperature degenerates as an ordinary differential equation. Along an electron streamline, two simple formulas for electron temperature and plasma potential are obtained. These formulas offer some insights, e.g., the electron temperature and plasma potential distributions along an electron streamline include two exponential functions, and the one for plasma potential includes an extra linear distribution function.

  4. Measurement of electron density and temperature in plasmas

    NASA Technical Reports Server (NTRS)

    Billman, K. W.; Rowley, P. D.; Presley, L. L.; Stallcop, J.

    1972-01-01

    Application of two laser wavelengths passing through plasma measures electron density and temperature. Function depends on determining absorption of light at two wavelengths. Nature of reaction is explained and schematic diagram of equipment is included.

  5. Electron temperature and density measurements of laser induced germanium plasma

    SciTech Connect

    Shakeel, Hira; Arshad, Saboohi; Haq, S. U. Nadeem, Ali

    2016-05-15

    The germanium plasma produced by the fundamental harmonics (1064 nm) of Nd:YAG laser in single and double pulse configurations have been studied spectroscopically. The plasma is characterized by measuring the electron temperature using the Boltzmann plot method for neutral and ionized species and electron number density as a function of laser irradiance, ambient pressure, and distance from the target surface. It is observed that the plasma parameters have an increasing trend with laser irradiance (9–33 GW/cm{sup 2}) and with ambient pressure (8–250 mbar). However, a decreasing trend is observed along the plume length up to 4.5 mm. The electron temperature and electron number density are also determined using a double pulse configuration, and their behavior at fixed energy ratio and different interpulse delays is discussed.

  6. Isoelectronic line intensity ratios for plasma electron temperature measurement (invited)

    NASA Astrophysics Data System (ADS)

    Marjoribanks, Robin S.; Budnik, Fredric; Kulcsár, Gábor; Zhao, Liang

    1995-01-01

    Strictly speaking, temperature is uniquely defined only in plasmas which are in complete thermodynamic equilibrium. In typical laser-produced plasmas, measurement of electron temperature amounts to a parametrization of some part of the distribution of electron energies, typically inferred from the recombination continuum, or from the ratio of spectral lines that are implicitly dependent on the electron distribution. Where the plasma is highly transient, suffers appreciable opacity, or is subject to a background radiation field, the interpretation of temperature from disparate spectral lines can become untrustworthy. For these complicated plasmas, a conceptually simpler spectral line diagnostic offers great advantages. A technique has been introduced that begins with plasmas that include two elements of similar atomic number, in a known ratio, and compares isoelectronic lines from ions that differ only in their nuclear charge Z, and thus in their ionization potentials χi. Since these two have different values of the same dimensionless parameter Te/χi, the ratio of intensities of isoelectronic lines can be interpreted to determine the temperature Te. The technique and its areas of advantage are described, the applications made to the special problems of laboratories elsewhere are summarized, and this particular progress in application to laser plasmas produced by high-intensity picosecond pulses are reported here.

  7. Separation of finite electron temperature effect on plasma polarimetry.

    PubMed

    Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori

    2012-12-01

    This study demonstrates the separation of the finite electron temperature on the plasma polarimetry in the magnetic confined fusion plasma for the first time. Approximate solutions of the transformed Stokes equation, including the relativistic effect, suggest that the orientation angle, θ, and ellipticity angle, ε, of polarization state have different dependency on the electron density, n(e), and the electron temperature, T(e), and that the separation of n(e) and T(e) from θ and ε is possible in principle. We carry out the equilibrium and kinetic reconstruction of tokamak plasma when the central electron density was 10(20) m(-3), and the central electron temperatures were 5, 10, 20, and 30 keV. For both cases when a total plasma current, I(p), is known and when I(p) is unknown, the profiles of plasma current density, j(φ), n(e), and T(e) are successfully reconstructed. The reconstruction of j(φ) without the information of I(p) indicates the new method of I(p) measurement applicable to steady state operation of tokamak.

  8. Separation of finite electron temperature effect on plasma polarimetry

    SciTech Connect

    Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori

    2012-12-15

    This study demonstrates the separation of the finite electron temperature on the plasma polarimetry in the magnetic confined fusion plasma for the first time. Approximate solutions of the transformed Stokes equation, including the relativistic effect, suggest that the orientation angle, {theta}, and ellipticity angle, {epsilon}, of polarization state have different dependency on the electron density, n{sub e}, and the electron temperature, T{sub e}, and that the separation of n{sub e} and T{sub e} from {theta} and {epsilon} is possible in principle. We carry out the equilibrium and kinetic reconstruction of tokamak plasma when the central electron density was 10{sup 20} m{sup -3}, and the central electron temperatures were 5, 10, 20, and 30 keV. For both cases when a total plasma current, I{sub p}, is known and when I{sub p} is unknown, the profiles of plasma current density, j{sub {phi}}, n{sub e}, and T{sub e} are successfully reconstructed. The reconstruction of j{sub {phi}} without the information of I{sub p} indicates the new method of I{sub p} measurement applicable to steady state operation of tokamak.

  9. Langmuir solitons in a plasma with inhomogeneous electron temperature

    NASA Astrophysics Data System (ADS)

    Gromov, Evgeny M.; Malomed, Boris A.

    2015-06-01

    Dynamics of Langmuir solitons is considered in plasmas with spatially inhomogeneous electron temperature. An underlying Zakharov-type system of two unidirectional equations for the Langmuir and ion-sound fields is reduced to an inhomogeneous nonlinear Schrödinger equation with spatial variation of the second-order dispersion and self-phase modulation coefficients, induced by a spatially inhomogeneous profile of the electron temperature. Analytical trajectories of motion of a soliton in the plasma with an electron-temperature hole, barrier, or cavity between two barriers are found, using the method of integral moments. The possibility of the soliton to pass a high-temperature barrier is shown too. Analytical results are well corroborated by numerical simulations.

  10. Equatorial plasma bubbles with enhanced ion and electron temperatures

    NASA Astrophysics Data System (ADS)

    Park, Jaeheung; Min, Kyoung Wook; Kim, Vitaly P.; Kil, Hyosub; Su, Shin-Yi; Chao, Chi Kuang; Lee, Jae-Jin

    2008-09-01

    While the ion and electron temperatures inside equatorial plasma bubbles (EPBs) are normally lower than those in an ambient plasma, bubbles with enhanced temperatures (BETs) are found occasionally in the topside ionosphere. Here we report the characteristics of BETs identified from observations of the first Republic of China Satellite (ROCSAT-1), the first Korea Multi-purpose Satellite (KOMPSAT-1), and the Defense Meteorological Satellite Program (DMSP) F15 during the solar maximum period between 2000 and 2001. The oxygen ion fraction inside the BETs, which was no lower than that of the ambient ionosphere, was similar to the case of ordinary low-temperature EPBs. These observations indicate that the BETs and low-temperature EPBs detected on the topside were produced by the upward drift of low-density plasma from lower altitudes. The feature that distinguishes BETs from normal EPBs is the occurrence of an unusually fast poleward field-aligned plasma flow relative to the ambient plasma. The BETs occurred preferentially around geomagnetic latitudes of 10° in the summer hemisphere, where the ambient ion and electron temperatures are lower than those in the conjugate winter hemisphere. The occurrence of BETs did not show any notable dependence on geomagnetic activities. The characteristics of the BETs suggest that the BETs were produced by adiabatic plasma heating associated with a fast poleward oxygen ion transport along magnetic flux tubes.

  11. Electron temperature effects on the eigenmodes of a plasma waveguide

    SciTech Connect

    Aghamir, F. M.; Abbas-nejad, M.

    2007-06-15

    The effect of finite electron temperature on the excitation of eigenmodes of a plasma loaded cylindrical waveguide is investigated. In the analysis, a nonlinear wave equation is derived using the linearized fluid equations along with Maxwell's equations. The general result obtained for the annular plasma column is then reduced to be used for the case in which the plasma column fills the entire waveguide as well as for a partially filled configuration. Dispersion relations for electromagnetic and electrostatic modes are solved numerically to study the effect of electron thermal velocity on the characteristics of azimuthally symmetrical eigenmodes. The numerical studies show that the thermal motion of electrons shifts the frequencies of the perturbed transverse magnetic waveguide and those of cyclotron plasma modes toward higher values.

  12. Electron Temperature Measurements in an Argon/Cesium Plasma Diode.

    DTIC Science & Technology

    1987-12-01

    MEASUREMENTS IN AN ARGON /CESIUM PLASMA DIODE 5, THESIS Michael J. Ward Second Lieutenant, USAF AFIT/GEP/ENP/87D-9 DTIC ELECTE FEB 1 01988 * DEPARTMENT OF...ENP/87D-9 S ELECTRON TEMPERATURE MEASUREMENTS IN AN ARGON /CESIUM PLASMA DIODE THESIS Presented to the Faculty of the School of Engineering of the Air...GEP/ENP/87D-9 * Abstract Line intensity measurements in an argon /cesium plasma *Q diode were made at various locations within the discharge, yielding a

  13. Etching with atomic precision by using low electron temperature plasma

    NASA Astrophysics Data System (ADS)

    Dorf, L.; Wang, J.-C.; Rauf, S.; Monroy, G. A.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

    2017-07-01

    There has been a steady increase in sub-nm precision requirement for many critical plasma etching processes in the semiconductor industry. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in conventional radio-frequency (RF) plasma processing systems, even during layer-by-layer or ‘atomic layer’ etch. To meet these increasingly stringent requirements, it is necessary to have an accurate control over ion energy and ion/radical composition during plasma processing. In this work, a new plasma etch system designed to facilitate atomic precision plasma processing is presented. An electron sheet beam parallel to the substrate surface is used to produce a plasma in this system. This plasma has a significantly lower electron temperature T e ~ 0.3 eV and ion energy E i  <  3 eV (without applied bias) compared to inductively and capacitively coupled RF plasmas. Electron beam plasmas also have a higher ion-to-radical ratio compared to RF plasmas, so this plasma etch system employs an independent radical source for accurate control over relative ion and radical concentrations. A low frequency RF bias capability that allows control of ion energy in the 2-50 eV range is another important component of this plasma etch system. The results of etching of a variety of materials and structures in this low-electron temperature plasma system are presented in this study: (1) layer-by-layer etching of p-Si at E i ~ 25-50 eV using electrical and gas cycling is demonstrated; (2) continuous etching of epi-grown µ-Si in Cl2-based plasmas is performed, showing that surface damage can be minimized by keeping E i  <  10 eV. Also presented are the results of molecular dynamics modeling of atomic precision etching at low E i.

  14. Atomic precision etch using a low-electron temperature plasma

    NASA Astrophysics Data System (ADS)

    Dorf, L.; Wang, J.-C.; Rauf, S.; Zhang, Y.; Agarwal, A.; Kenney, J.; Ramaswamy, K.; Collins, K.

    2016-03-01

    Sub-nm precision is increasingly being required of many critical plasma etching processes in the semiconductor industry. Accurate control over ion energy and ion/radical composition is needed during plasma processing to meet these stringent requirements. Described in this work is a new plasma etch system which has been designed with the requirements of atomic precision plasma processing in mind. In this system, an electron sheet beam parallel to the substrate surface produces a plasma with an order of magnitude lower electron temperature Te (~ 0.3 eV) and ion energy Ei (< 3 eV without applied bias) compared to conventional radio-frequency (RF) plasma technologies. Electron beam plasmas are characterized by higher ion-to-radical fraction compared to RF plasmas, so a separate radical source is used to provide accurate control over relative ion and radical concentrations. Another important element in this plasma system is low frequency RF bias capability which allows control of ion energy in the 2-50 eV range. Presented in this work are the results of etching of a variety of materials and structures performed in this system. In addition to high selectivity and low controllable etch rate, an important requirement of atomic precision etch processes is no (or minimal) damage to the remaining material surface. It has traditionally not been possible to avoid damage in RF plasma processing systems, even during atomic layer etch. The experiments for Si etch in Cl2 based plasmas in the aforementioned etch system show that damage can be minimized if the ion energy is kept below 10 eV. Layer-by-layer etch of Si is also demonstrated in this etch system using electrical and gas pulsing.

  15. Electron Temperature and Plasma Flow Measurements of NIF Hohlraum Plasmas

    NASA Astrophysics Data System (ADS)

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brow, G. V.; Regan, S. P.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Eder, D.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Jaquez, J.; Huang, H.; Hansen, S. B.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.; LLNL Collaboration; LLE Collaboration; GA Collaboration; SNL Collaboration

    2016-10-01

    Characterizing the plasma conditions inside NIF hohlraums, in particular mapping the plasma Te, is critical to gaining insight into mechanisms that affect energy coupling and transport in the hohlraum. The dot spectroscopy platform provides a temporal history of the localized Te and plasma flow inside a NIF hohlraum, by introducing a Mn-Co tracer dot, at strategic locations inside the hohlraum, that comes to equilibrium with the local plasma. K-shell X-ray spectroscopy of the tracer dot is recorded onto an absolutely calibrated X-ray streak spectrometer. Isoelectronic and interstage line ratios are used to infer localized Te through comparison with atomic physics calculations using SCRAM. Time resolved X-ray images are simultaneously taken of the expanding dot, providing plasma (ion) flow information. We present recent results provided by this platform and compare with simulations using HYDRA. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  16. Measurements of electron number density and plasma temperature using LIBS

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao-xia; Luo, Wen-feng; He, Jun-fang; Wang, Hong-ying; Yang, Sen-lin; Li, Yuan-yuan

    2016-10-01

    Plasma produced by the radiation of a 1064 nm Nd:YAG laser focused onto a standard aluminum alloy E311 was studied spectroscopically. The electron density was inferred by measuring the Stark broadened line profile of Cu I 324.75 nm at a distance of 1.5 mm from the target surface with the laser irradiance of 3.27 GW/cm2. The electron temperature was determined using the Boltzmann plot method with eight neutral iron lines. At the same time, the validity of the assumption of local thermodynamic equilibrium was discussed in light of the results obtained.

  17. To the problem of electron temperature control in plasma

    SciTech Connect

    Galechyan, G.A.; Anna, P.R.

    1995-12-31

    One of the main problems in low temperature plasma is control plasma parameters at fixed values of current and gas pressure in the discharge. It is known that an increase in the intensity of sound wave directed along the positive column to values in excess of a definite threshold leads to essential rise of the temperature of electrons. However, no less important is the reduction of electron temperature in the discharge down to the value less than that in plasma in the absence external influence. It is known that to reduce the electron temperature in the plasma of CO{sub 2} laser, easily ionizable admixture are usually introduced in the discharge area with the view of increasing the overpopulation. In the present work we shall show that the value of electron temperature can be reduced by varying of sound wave intensity at its lower values. The experiment was performed on an experimental setup consisted of the tube with length 52 cm and diameter 9.8 cm, two electrodes placed at the distance of 27 cm from each other. An electrodynamical radiator of sound wave was fastened to one of tube ends. Fastened to the flange at the opposite end was a microphone for the control of sound wave parameters. The studies were performed in range of pressures from 40 to 180 Torr and discharge currents from 40 to 110 mA. The intensity of sound wave was varied from 74 to 92 dB. The measurement made at the first resonance frequency f = 150 Hz of sound in the discharge tube, at which a quarter of wave length keep within the length of the tube. The measurement of longitudinal electric field voltage in plasma of positive column was conducted with the help of two probes according to the compensation method. Besides, the measurement of gas temperature in the discharge were taken. Two thermocouple sensors were arranged at the distance of 8 cm from the anode, one of them being installed on the discharge tube axis, the second-fixed the tube wall.

  18. Determining Electron Density, Pressure, and Temperature in Jupiter's Plasma Sheet Using the Galileo Plasma Wave Instrument

    NASA Astrophysics Data System (ADS)

    Ansher, J. A.; Gurnett, D. A.; Khurana, K. K.; Kivelson, M. G.

    2001-05-01

    The plasma wave instrument on board the Galileo spacecraft can be used to determine electron density in Jupiter's magnetosphere. Ordinary mode radio waves are often detected in the form of non-thermal continuum radiation trapped in the magnetosphere at frequencies above the electron plasma frequency. By identifying the low-frequency cutoff of continuum radiation as the plasma frequency, an upper limit to the local electron density can be calculated. This technique has been used with the Galileo plasma wave data to provide an electron density data set with approximately 37-second time resolution. Continuum radiation is detected by the plasma wave instrument in much of Galileo's primary mission and electron density can be calculated at all System-III longitudes and radial distances beyond about 20-25 RJ. The density data set created using this technique is used here in conjunction with data from the Galileo magnetometer instrument and with Khurana's 1998 mathematical model of Jupiter's plasma sheet to study pressure balance in the plasma sheet. As Jupiter rotates, the spacecraft encounters the plasma sheet and crosses the entire sheet from north to south, or south to north, in under five hours. Assuming there are no time dependent variations in the plasma sheet on this time scale, and negligible curvature to the magnetic field lines in this region, the sum of magnetic pressure and particle pressure across the plasma sheet should stay constant. Using electron density and magnetic field data, and varying the temperature parameter, best fits for the total constant pressure and the corresponding temperature can be determined. These values can be determined throughout Jupiter's magnetosphere yielding pressure and temperature profiles of Jupiter's plasma sheet between about 20 and 140 RJ. Typical temperatures determined using this technique are about 108 K, corresponding to energies of about 10 keV. The total pressure decreases with radial distance from Jupiter as a power

  19. Nonlocal collisionless and collisional electron transport in low temperature plasmas

    NASA Astrophysics Data System (ADS)

    Kaganovich, Igor

    2009-10-01

    The purpose of the talk is to describe recent advances in nonlocal electron kinetics in low-pressure plasmas. A distinctive property of partially ionized plasmas is that such plasmas are always in a non-equilibrium state: the electrons are not in thermal equilibrium with the neutral species and ions, and the electrons are also not in thermodynamic equilibrium within their own ensemble, which results in a significant departure of the electron velocity distribution function from a Maxwellian. These non-equilibrium conditions provide considerable freedom to choose optimal plasma parameters for applications, which make gas discharge plasmas remarkable tools for a variety of plasma applications, including plasma processing, discharge lighting, plasma propulsion, particle beam sources, and nanotechnology. Typical phenomena in such discharges include nonlocal electron kinetics, nonlocal electrodynamics with collisionless electron heating, and nonlinear processes in the sheaths and in the bounded plasmas. Significant progress in understanding the interaction of electromagnetic fields with real bounded plasma created by this field and the resulting changes in the structure of the applied electromagnetic field has been one of the major achievements of the last decade in this area of research [1-3]. We show on specific examples that this progress was made possible by synergy between full scale particle-in-cell simulations, analytical models, and experiments. In collaboration with Y. Raitses, A.V. Khrabrov, Princeton Plasma Physics Laboratory, Princeton, NJ, USA; V.I. Demidov, UES, Inc., 4401 Dayton-Xenia Rd., Beavercreek, OH 45322, USA and AFRL, Wright-Patterson AFB, OH 45433, USA; and D. Sydorenko, University of Alberta, Edmonton, Canada. [4pt] [1] D. Sydorenko, A. Smolyakov, I. Kaganovich, and Y. Raitses, IEEE Trans. Plasma Science 34, 895 (2006); Phys. Plasmas 13, 014501 (2006); 14 013508 (2007); 15, 053506 (2008). [0pt] [2] I. D. Kaganovich, Y. Raitses, D. Sydorenko, and

  20. Sustenance of inhomogeneous electron temperature in a magnetized plasma column

    SciTech Connect

    Karkari, S. K. Mishra, S. K.; Kaw, P. K.

    2015-09-15

    This paper presents the equilibrium properties of a magnetized plasma column sustained by direct-current (dc) operated hollow cathode discharge in conjunction with a conducting end-plate, acting as the anode. The survey of radial plasma characteristics, performed in argon plasma, shows hotter plasma in the periphery as compared to the central plasma region; whereas the plasma density peaks at the center. The off-centered peak in radial temperature is attributed due to inhomogeneous power deposition in the discharge volume in conjunction with short-circuiting effect by the conducting end plate. A theoretical model based on particle flux and energy balance is given to explain the observed characteristics of the plasma column.

  1. Electron temperature and average density in spherical laser-produced plasmas - Ultraviolet plasma spectroscopy

    NASA Technical Reports Server (NTRS)

    Goldsmith, S.; Seely, J. F.; Feldman, U.; Behring, W. E.; Cohen, L.

    1985-01-01

    The average values of the electron temperature Te and the electron density Ne in the corona plasmas of spherically irradiated high-Z targets have been estimated. Targets composed of the elements Cu through Br, Rb, and Mo were irradiated using the fundamental (1.06 microns) and the frequency-tripled (351 nm) output of the Omega laser system. Spectra were recorded in the wavelength region 15-200 A. Using various extreme ultraviolet spectroscopic techniques, it is found that for the case of a Mo plasma produced by frequency-tripled laser irradiation, Te = 2600 + or - 600 eV and Ne is greater than 6 x 10 to the 20th/cu cm. This is consistent with a 'flux limit' smaller than 0.1. The estimated values of Te and Ne are lower in the corona plasmas produced using the fundamental (1.06 micron) irradiation.

  2. Nonlocal control of electron temperature in short direct current glow discharge plasma

    SciTech Connect

    Demidov, V. I.; Kudryavtsev, A. A.; Stepanova, O. M.; Kurlyandskaya, I. P.

    2014-09-15

    To demonstrate controlling the electron temperature in nonlocal plasma, experiments have been performed on a short (without positive column) dc glow discharge with a cold cathode by applying different voltages to the conducting discharge wall. The experiments have been performed for low-pressure noble gas discharges. The applied voltage can modify trapping the energetic electrons emitted from the cathode sheath and arising from the atomic and molecular processes in the plasma within the device volume. This phenomenon results in the energetic electrons heating the slow plasma electrons, which consequently modifies the electron temperature. Furthermore, a numerical model of the discharge has demonstrated the electron temperature modification for the above case.

  3. Electromagnetic electron temperature gradient driven instability in toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Zielinski, J.; Smolyakov, A. I.; Beyer, P.; Benkadda, S.

    2017-02-01

    The fluid theory of a new type of electron temperature gradient instability is proposed. This mode is closely related to the short wavelength Alfvén mode in the regime k⊥ 2 ρi 2 > 1 . Contrary to standard electron temperature gradient modes, which are mostly electrostatic, the considered mode is fundamentally electromagnetic and does not exist in the electrostatic limit. The mechanism of instability relies on gradients in both the electron temperature and magnetic field. It is suggested that this instability may be a destabilizing mechanism for collisionless microtearing modes, which are observed in a number of gyrokinetic simulations.

  4. Electron Temperature Derived from Measurements of Complex Plasma Impedance

    DTIC Science & Technology

    2008-10-20

    arrangements and technique ............................................................................................ 5 IV. Experimental Results and...current versus an applied potential sweep (the probe characteristic) is a standard plasma diagnostic technique for determining electron density and...uncertainties both with respect to probe geometry, and errors associated with the fitting procedure itself. This can render fitting techniques

  5. 2-D Imaging of Electron Temperature in Tokamak Plasmas

    SciTech Connect

    T. Munsat; E. Mazzucato; H. Park; C.W. Domier; M. Johnson; N.C. Luhmann Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol

    2004-07-08

    By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented.

  6. Electron temperature measurement in Maxwellian non-isothermal beam plasma of an ion thruster

    SciTech Connect

    Zhang, Zun; Tang, Haibin Kong, Mengdi; Zhang, Zhe; Ren, Junxue

    2015-02-15

    Published electron temperature profiles of the beam plasma from ion thrusters reveal many divergences both in magnitude and radial variation. In order to know exactly the radial distributions of electron temperature and understand the beam plasma characteristics, we applied five different experimental approaches to measure the spatial profiles of electron temperature and compared the agreement and disagreement of the electron temperature profiles obtained from these techniques. Experimental results show that the triple Langmuir probe and adiabatic poly-tropic law methods could provide more accurate space-resolved electron temperature of the beam plasma than other techniques. Radial electron temperature profiles indicate that the electrons in the beam plasma are non-isothermal, which is supported by a radial decrease (∼2 eV) of electron temperature as the plume plasma expands outward. Therefore, the adiabatic “poly-tropic law” is more appropriate than the isothermal “barometric law” to be used in electron temperature calculations. Moreover, the calculation results show that the electron temperature profiles derived from the “poly-tropic law” are in better agreement with the experimental data when the specific heat ratio (γ) lies in the range of 1.2-1.4 instead of 5/3.

  7. Characteristic temperatures and electron number densities in an R.F. capacitively coupled plasma.

    PubMed

    Anghel, S D; Frentiu, T; Darvasi, E; Rusu, A M; Simon, A; Cordos, E A

    1996-06-01

    The excitation temperatures of Ar and Fe, the ionization temperatures of Ar and Ca and the electron number densities have been determined for a radiofrequency capacitively coupled plasma in the tip-ring electrode geometry. The temperatures and the electron number densities possess their maximum value close to the electrodes.

  8. Probing plasma turbulence by modulating the electron temperature gradient

    SciTech Connect

    DeBoo, J. C.; Petty, C. C.; Holland, C.; Rhodes, T. L.; Schmitz, L.; Wang, G.; Doyle, E. J.; Hillesheim, J.; Peebles, W. A.; Zeng, L.; White, A. E.; Austin, M. E.; Yan, Z.

    2010-05-15

    The local value of a/L{sub Te}, a turbulence drive term, was modulated with electron cyclotron heating in L-mode discharges on DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] and the density and electron temperature fluctuations in low, intermediate, and high-k regimes were measured and compared with nonlinear gyrokinetic turbulence simulations using the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)]. The local drive term at rhoapprox0.6 was reduced by up to 50%, which produced comparable reductions in electron temperature fluctuations at low-k. At intermediate k, k{sub t}hetaapprox4 cm{sup -1} and k{sub t}hetarho{sub s}approx0.8, a very interesting and unexpected result was observed where density fluctuations increased by up to 10% when the local drive term was decreased by 50%. Initial comparisons of simulations from GYRO with the thermal diffusivity from power balance analysis and measured turbulence response are reported. Simulations for the case with the lowest drive term are challenging as they are near the marginal value of a/L{sub Te} for trapped electron mode activity.

  9. Linear electrostatic waves in two-temperature electron-positron plasmas

    NASA Astrophysics Data System (ADS)

    Lazarus, I. J.; Bharuthram, R.; Singh, S. V.; Pillay, S. R.; Lakhina, G. S.; Lakhina

    2012-12-01

    Linear electrostatic waves in a magnetized four-component, two-temperature electron-positron plasma are investigated, with the hot species having the Boltzmann density distribution and the dynamics of cooler species governed by fluid equations with finite temperatures. A linear dispersion relation for electrostatic waves is derived for the model and analyzed for different wave modes. Analysis of the dispersion relation for perpendicular wave propagation yields a cyclotron mode with contributions from both cooler and hot species, which in the absence of hot species goes over to the upper hybrid mode of cooler species. For parallel propagation, both electron-acoustic and electron plasma modes are obtained, whereas for a single-temperature electron-positron plasma, only electron plasma mode can exist. Dispersion characteristics of these modes at different propagation angles are studied numerically.

  10. Determination of the Electron Temperature in a Low Pressure Dusty Radiofrequency Methane Plasma

    SciTech Connect

    Massereau-Guilbaud, Veronique; Geraud-Grenier, Isabelle; Plain, Andre

    2011-11-29

    The particles are obtained by PECVD in radiofrequency (13.56 MHz) low pressure plasmas (90%CH4-10%Ar). During the particle growth, the particles trap electrons and modify the EEDF, and the electrical and optical characteristics of the plasma. The plasma is analyzed by Optical Emission Spectroscopy. The excitation temperature and the electron temperature are calculated from the H{sub {alpha}}, H{sub {beta}}, H{sub {gamma}} Balmer hydrogen line intensities and from Ar ones. The temporal evolutions of the temperatures during the particle formation are compared and discussed.

  11. Height variation of electron temperature associated with equatorial plasma bubbles - some recent rocket observations

    NASA Astrophysics Data System (ADS)

    Muralikrishna, P.; Batista, I. S.; Domingos, S.; Aquino, M. G.

    2013-05-01

    In-situ measurements made from Brazil recently using rocket-borne swept-bias Langmuir Probes show that the electron temperatures in the valley region between the equatorial E and F regions get modified before the onset of plasma bubbles. During one of the post sunset launches made on 18-th December 1995 from the equatorial rocket launching station CLA in Alcântara, Brazil the Langmuir probe measured abnormally large electron temperatures below the F-region just before the onset of plasma bubbles but temperatures became normal soon after the onset of bubbles. Later on 2-nd December 2011 a Brazilian VS-30 single stage rocket was launched from the equatorial rocket launching station CLBI in Natal, Brazil carrying a Langmuir probe operating alternately in swept and constant bias modes to measure both electron temperature and electron density respectively. The ground equipments operated before and during the rocket launch clearly showed the presence of plasma bubbles above the F-region. At the time of launch the bubble activity was at its peak. The electron density and temperature height profiles could be estimated from the LP data up to the rocket apogee altitude of 139km. During the rocket upleg and downleg the valley region showed the presence electron temperatures as high as 2000 degree K while the temperatures expected from the existing models are around 500 degree K. A two stage VS-30/Orion rocket was launched on 8-th December soon after sunset carrying a Langmuir Probe operating alternately in swept and constant bias modes to measure the electron density and electron temperature, mainly in the valley between the E and F regions. At the time of launch ground equipments operated at equatorial stations showed ionospheric conditions favorable for the generation of plasma bubbles. These profiles are compared with model electron density and temperature profiles as well as with electron density and temperature profiles observed under conditions of no plasma bubbles.

  12. Time-dependent electron temperature diagnostics for high-power, aluminum z-pinch plasmas

    NASA Astrophysics Data System (ADS)

    Sanford, T. W. L.; Nash, T. J.; Mock, R. C.; Spielman, R. B.; Seamen, J. F.; McGurn, J. S.; Jobe, D.; Gilliland, T. L.; Vargas, M.; Whitney, K. G.; Thornhill, J. W.; Pulsifer, P. E.; Apruzese, J. P.

    1997-01-01

    Time-resolved x-ray pinhole photographs and time-integrated radially resolved x-ray crystal-spectrometer measurements of azimuthally symmetric aluminum-wire implosions suggest that the densest phase of the pinch is composed of a hot plasma core surrounded by a cooler plasma halo. The slope of the free-bound x-ray continuum, provides a time-resolved, model-independent diagnostic of the core electron temperature. A simultaneous measurement of the time-resolved K-shell line spectra provides the electron temperature of the spatially averaged plasma. Together, the two diagnostics support a one-dimensional radiation-hydrodynamic model prediction of a plasma whose thermalization on axis produces steep radial gradients in temperature, from temperatures in excess of 1 kV in the core to below 1 kV in the surrounding plasma halo.

  13. Experimental observation of electron-temperature-gradient turbulence in a laboratory plasma.

    PubMed

    Mattoo, S K; Singh, S K; Awasthi, L M; Singh, R; Kaw, P K

    2012-06-22

    We report the observation of electron-temperature-gradient (ETG) driven turbulence in the laboratory plasma of a large volume plasma device. The removal of unutilized primary ionizing and nonthermal electrons from uniform density plasma and the imposition and control of the gradient in the electron temperature (T[Symbol: see text] T(e)) are all achieved by placing a large (2 m diameter) magnetic electron energy filter in the middle of the device. In the dressed plasma, the observed ETG turbulence in the lower hybrid range of frequencies ν = (1-80 kHz) is characterized by a broadband with a power law. The mean wave number k perpendicular ρ(e) = (0.1-0.2) satisfies the condition k perpendicular ρ(e) ≤ 1, where ρ(e) is the electron Larmor radius.

  14. Arbitrary amplitude kinetic Alfven solitary waves in two temperature electron superthermal plasma

    NASA Astrophysics Data System (ADS)

    Singh, Manpreet; Singh Saini, Nareshpal; Ghai, Yashika

    2016-07-01

    Through various satellite missions it is observed that superthermal velocity distribution for particles is more appropriate for describing space and astrophysical plasmas. So it is appropriate to use superthermal distribution, which in the limiting case when spectral index κ is very large ( i.e. κ→∞), shifts to Maxwellian distribution. Two temperature electron plasmas have been observed in auroral regions by FAST satellite mission, and also by GEOTAIL and POLAR satellite in the magnetosphere. Kinetic Alfven waves arise when finite Larmor radius effect modifies the dispersion relation or characteristic perpendicular wavelength is comparable to electron inertial length. We have studied the kinetic Alfven waves (KAWs) in a plasma comprising of positively charged ions, superthermal hot electrons and Maxwellian distributed cold electrons. Sagdeev pseudo-potential has been employed to derive an energy balance equation. The critical Mach number has been determined from the expression of Sagdeev pseudo-potential to see the existence of solitary structures. It is observed that sub-Alfvenic compressive solitons and super-Alfvenic rarefactive solitons exist in this plasma model. It is also observed that various parameters such as superthermality of hot electrons, relative concentration of cold and hot electron species, Mach number, plasma beta, ion to cold electron temperature ratio and ion to hot electron temperature ratio have significant effect on the amplitude and width of the KAWs. Findings of this investigation may be useful to understand the dynamics of coherent non-linear structures (i.e. KAWs) in space and astrophysical plasmas.

  15. Real time two-dimensional spatial distribution measurement method of electron temperature and plasma density

    NASA Astrophysics Data System (ADS)

    Kim, Young Cheol; Jang, Sung Ho; Kim, Gun Ho; Chung, Chin Wook

    2009-10-01

    Real time two-dimensional spatial distribution measurement method of electron temperature and plasma density was developed. It is based on a floating probe method [1] because the floating probe has high time resolution. Two-dimensional array of sensors on a 300 mm diameter wafer-shaped printed circuit board (PCB) and a high speed multiplexer circuit were used for real time distribution measurement. The method was tested at various powers and pressures, spatial distributions of the electron temperature and the plasma density could be obtained. And in the measurement results, asymmetric plasma density distributions caused by pumping port effect could be observed. This method can measure spatial distribution of plasma parameters on the wafer in real time without plasma perturbation, therefore it will be expected to improve the uniformity of processing plasmas such as etching and deposition. [4pt] [1] M. H. Lee, S. H. Jang, C. W. Chung, J. Appl. Phys. 101, 033305 (2007).

  16. Plasma-Wall Interaction and Electron Temperature Saturation in Hall Thrusters

    NASA Astrophysics Data System (ADS)

    Smirnov, Artem

    2005-10-01

    Existing Hall thruster models predict that secondary electron emission from the channel walls is significant and that the near-wall sheaths are space charge saturated. The plasma-wall interaction and its dependence on the discharge voltage and channel width were studied through the measurements of the electron temperature, plasma potential, and plasma density in a 2 kW Hall thruster [1,2]. The experimental electron-wall collision frequency is computed using the measured plasma parameters. For high discharge voltages, the deduced electron-wall collision frequency is much lower than the theoretical value obtained for the space charge saturated sheath regime, but larger than the wall recombination frequency. The observed electron temperature saturation appears to be directly associated with a decrease of the Joule heating, rather than with the enhancement of the electron energy loss at the walls due to a strong secondary electron emission. The channel width is shown to have a more significant effect on the axial distribution of the plasma potential than the discharge voltage. 1. Y. Raitses, D. Staack, M. Keidar, and N.J. Fisch, Phys. Plasmas 12, 057104 (2005). 2. Y. Raitses, D. Staack, A. Smirnov, and N.J. Fisch, Phys. Plasmas 12, 073507 (2005).

  17. Threefold Increase of the Bulk Electron Temperature of Plasma Discharges in a Magnetic Mirror Device

    NASA Astrophysics Data System (ADS)

    Bagryansky, P. A.; Shalashov, A. G.; Gospodchikov, E. D.; Lizunov, A. A.; Maximov, V. V.; Prikhodko, V. V.; Soldatkina, E. I.; Solomakhin, A. L.; Yakovlev, D. V.

    2015-05-01

    This Letter describes plasma discharges with a high temperature of bulk electrons in the axially symmetric high-mirror-ratio (R =35 ) open magnetic system gas dynamic trap (GDT) in the Budker Institute (Novosibirsk). According to Thomson scattering measurements, the on-axis electron temperature averaged over a number of sequential shots is 660 ±50 eV with the plasma density being 0.7 ×1 019 m-3 ; in few shots, electron temperature exceeds 900 eV. This corresponds to at least a threefold increase with respect to previous experiments both at GDT and at other comparable machines, thus, demonstrating the highest quasistationary (about 1 ms) electron temperature achieved in open traps. The breakthrough is made possible by application of a new 0.7 MW /54.5 GHz electron cyclotron resonance heating system in addition to standard 5 MW heating by neutral beams, and application of a radial electric field to mitigate the flute instability.

  18. Reduced electron temperature in a magnetized inductively-coupled plasma with internal coil

    SciTech Connect

    Arancibia Monreal, J.; Chabert, P.; Godyak, V.

    2013-10-15

    The effect of magnetic filtering on the electron energy distribution function is studied in an inductive discharge with internal coil coupling. The coil is placed inside the plasma and driven by a low-frequency power supply (5.8 MHz) which leads to a very high power transfer efficiency. A permanent dipole magnet may be placed inside the internal coil to produce a static magnetic field around 100 Gauss. The coil and the matching system are designed to minimize the capacitive coupling to the plasma. Capacitive coupling is quantified by measuring the radiofrequency (rf) plasma potential with a capacitive probe. Without the permanent magnet, the rf plasma potential is significantly smaller than the electron temperature. When the magnet is present, the rf plasma potential increases. The electron energy distribution function is measured as a function of space with and without the permanent magnet. When the magnet is present, electrons are cooled down to low temperature in the downstream region. This region of low electron temperature may be useful for plasma processing applications, as well as for efficient negative ion production.

  19. Reduced electron temperature in a magnetized inductively-coupled plasma with internal coil

    NASA Astrophysics Data System (ADS)

    Arancibia Monreal, J.; Chabert, P.; Godyak, V.

    2013-10-01

    The effect of magnetic filtering on the electron energy distribution function is studied in an inductive discharge with internal coil coupling. The coil is placed inside the plasma and driven by a low-frequency power supply (5.8 MHz) which leads to a very high power transfer efficiency. A permanent dipole magnet may be placed inside the internal coil to produce a static magnetic field around 100 Gauss. The coil and the matching system are designed to minimize the capacitive coupling to the plasma. Capacitive coupling is quantified by measuring the radiofrequency (rf) plasma potential with a capacitive probe. Without the permanent magnet, the rf plasma potential is significantly smaller than the electron temperature. When the magnet is present, the rf plasma potential increases. The electron energy distribution function is measured as a function of space with and without the permanent magnet. When the magnet is present, electrons are cooled down to low temperature in the downstream region. This region of low electron temperature may be useful for plasma processing applications, as well as for efficient negative ion production.

  20. Laboratory observations of electron temperature in the wake of a sphere in a streaming plasma

    NASA Technical Reports Server (NTRS)

    Oran, W. A.; Stone, N. H.; Samir, U.; Fontheim, E. G.

    1975-01-01

    A parametric study was performed of electron-temperature variation in the wake of a conducting sphere in a streaming plasma. The flow conditions were varied as follows: the ambient electron temperatures in the range from 850 to 2450 K; the ambient electron densities in the range from 0.0005 to 0.00007 per cu cm; and body potentials relative to plasma potential in the range from +1.7 to -2.8 V for an ion-beam energy of approximately 4 eV. Electron-temperature enhancements were observed which ranged up to 200 per cent above ambient in the nearest proximity of the body surface. The magnitude of the enhancement depends upon the ambient density, temperature, and body potential.

  1. Oblique shock waves in a two electron temperature superthermally magnetized plasma

    NASA Astrophysics Data System (ADS)

    Bains, A. S.; Panwar, A.; Ryu, C. M.

    2015-11-01

    A study is presented for the oblique propagation of low-frequency ion acoustic ( IA) shock waves in a magnetized plasma consisting of cold ions and two temperature superthermally distributed electrons. A nonlinear Korteweg de-Vries-Burger ( KdV-Burger) equation is obtained by using the reductive perturbation method (RPM) which governs the dynamics of the IA shock wave. Using the solution of KdV-Burger equation, the characteristics of the IA shock wave have been studied for various plasma parameters. The combined effects of the cold to hot electron temperature ratio (σ), the density ratio of hot electrons to ions (f), the superthermality of cold and hot electrons (κc, κh), the strength of the magnetic field (ω_{ci}), and the obliqueness (θ), significantly influence the profile of the shock wave. The findings in the present study could be important for the electrostatic wave structures in the Saturn's magnetosphere, where two temperature electrons exist with a kappa distribution.

  2. Dust-acoustic solitary structures in a magnetized dusty plasma with two-temperature nonextensive electrons

    SciTech Connect

    Emamuddin, M.; Yasmin, S.; Asaduzzaman, M.; Mamun, A. A.

    2013-08-15

    The nonlinear propagation of dust-acoustic (DA) waves in an obliquely propagating magnetized dusty plasma, containing nonextensively distributed electrons of distinct temperatures (namely lower and higher temperature nonextensive electrons), negatively charged mobile dust grains, and Maxwellian ions, is rigorously studied and analyzed by deriving the Zakharov-Kuznetsov equation. It is found that the characteristics of the DA solitary waves (DASWs) are significantly modified by the external magnetic field, obliqueness of the system, nonextensivity of the electrons, electron temperature-ratios, and the respective number densities of two species of electrons. The results obtained from this analysis can be employed in understanding and treating the structures and the characteristics of DASWs both in laboratory and astrophysical plasma system.

  3. Quantum Cohesion Oscillation of Electron Ground State in Low Temperature Laser Plasma

    NASA Technical Reports Server (NTRS)

    Zhao, Qingxun; Zhang, Ping; Dong, Lifang; Zhang, Kaixi

    1996-01-01

    The development of radically new technological and economically efficient methods for obtaining chemical products and for producing new materials with specific properties requires the study of physical and chemical processes proceeding at temperature of 10(exp 3) to 10(exp 4) K, temperature range of low temperature plasma. In our paper, by means of Wigner matrix of quantum statistical theory, a formula is derived for the energy of quantum coherent oscillation of electron ground state in laser plasma at low temperature. The collective behavior would be important in ion and ion-molecule reactions.

  4. Influence of laser energy on the electron temperature of a laser-induced Mg plasma

    NASA Astrophysics Data System (ADS)

    Asamoah, Emmanuel; Hongbing, Yao

    2017-01-01

    The magnesium plasma induced by a 1064-nm Q-switched Nd:YAG laser in atmospheric air was investigated. The evolution of the plasma was studied by acquiring spectral images at different laser energies and delay times. We observed that the intensities of the spectral lines decrease with larger delay times. The electron temperature was determined using the Boltzmann plot method. At a delay time of 100 ns and laser energy of 350 mJ, the electron temperature attained their highest value at 10164 K and then decreases slowly up to 8833.6 K at 500 ns. We found that the electron temperature of the magnesium plasma increases rapidly with increasing laser energy.

  5. Simultaneous measurement of electron temperature and density by a line pair method in the RFP plasma

    NASA Astrophysics Data System (ADS)

    Watanabe, Masayuki; Shimizu, S.; Ogawa, H.; Shinohara, T.

    2009-11-01

    A line-pair-method has been applied for a simultaneous measurement of the electron temperature and density in ATRAS RFP plasma. Three helium spectrum lines (668nm, 706nm, 728nm) were measured during the discharge at the same time and the electron temperature and density is estimated by using a Collision-Radiation model. To get the signal of the helium impunity line from the RFP discharge, the RFP plasma in the hydrogen gas with a few mixed helium gas was formed. In the typical ATRAS RFP discharge of the plasma current of 60kA, the electron temperature was approximately 50-150 eV and the electron density is the order of 10^18 m-3. During the discharge, the change of the temperature and density are mutually related and this correlation was the almost reverse phase. The periodically change of the temperature and density were also observed. This change synchronizes with a periodically increase of the averaged toroidal magnetic field, which is caused by the toroidal rotation of the increase of the toroidal magnetic field. This rotation, which is deeply related with dynamo effect, makes the plasma energy lose and particles also diffuse toward the plasma edge. As a result, the recycling of the particle and energy are occurred at the same time.

  6. Effects of relativistic electron temperature on parametric instabilities for intense laser propagation in underdense plasma

    SciTech Connect

    Zhao, Yao; Zheng, Jun; Chen, Min; Yu, Lu-Le; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming E-mail: zhengming.sheng@strath.ac.uk

    2014-11-15

    Effects of relativistic electron temperature on stimulated Raman scattering and stimulated Brillouin scattering instabilities for high intensity lasers propagating in underdense plasma are studied theoretically and numerically. The dispersion relations for these instabilities are derived from the relativistic fluid equation. For a wide range of laser intensity and electron temperature, it is found that the maximum growth rate and the instability region in k-space can be reduced at relativistic electron temperature. Particle-in-cell simulations are carried out, which confirm the theoretical analysis.

  7. Arbitrary amplitude slow electron-acoustic solitons in three-electron temperature space plasmas

    SciTech Connect

    Mbuli, L. N.; Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2015-06-15

    We examine the characteristics of large amplitude slow electron-acoustic solitons supported in a four-component unmagnetised plasma composed of cool, warm, hot electrons, and cool ions. The inertia and pressure for all the species in this plasma system are retained by assuming that they are adiabatic fluids. Our findings reveal that both positive and negative potential slow electron-acoustic solitons are supported in the four-component plasma system. The polarity switch of the slow electron-acoustic solitons is determined by the number densities of the cool and warm electrons. Negative potential solitons, which are limited by the cool and warm electron number densities becoming unreal and the occurrence of negative potential double layers, are found for low values of the cool electron density, while the positive potential solitons occurring for large values of the cool electron density are only limited by positive potential double layers. Both the lower and upper Mach numbers for the slow electron-acoustic solitons are computed and discussed.

  8. Estimations of electron densities and temperatures in He-3 dominated plasmas. [in nuclear pumped lasers

    NASA Technical Reports Server (NTRS)

    Depaola, B. D.; Marcum, S. D.; Wrench, H. K.; Whitten, B. L.; Wells, W. E.

    1979-01-01

    It is very useful to have a method of estimation for electron temperature and electron densities in nuclear pumped plasmas because measurements of such quantities are very difficult. This paper describes a method, based on rate equation analysis of the ionized species in the plasma and the electron energy balance. In addition to the ionized species, certain neutral species must also be calculated. Examples are given for pure helium and a mixture of helium and argon. In the HeAr case, He(+), He2(+), He/2 3S/, Ar(+), Ar2(+), and excited Ar are evaluated.

  9. Electron Beam Fluorescence Temperature Measurements of N2 in a SemiConductor Plasma Reactor

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Cattolica, Robert; Tynan George, R.

    2003-10-01

    The rotational temperature of nitrogen molecules in inductively coupled plasma (ICP) discharge has been measured using the electron beam fluorescence (EBF) technique. The neutral gas temperature is an important parameter in understanding the energy balance and neutral radical uniformity in plasma processing. The EBF technique has been used to study rarefied flows, but has not been applied previously to characterize a semiconductor plasma reactor. In this work an electron beam was integrated into an inductively coupled semiconductor plasma reactor, and was used to excite neutral nitrogen molecules from the N2X1 state into the excited molecular ion N2+B2 state. The electron-beam excitation process maps the rotational population distribution of the original ground state into the excited molecular ion state following a dipole model with deltaK=+/-1. The rotational temperature, which is equivalent to the neutral gas translational temperature under plasma reactor conditions, can be determined from the rotational intensity distribution of the fluorescence spectrum from the N2+B2 state. For the range of neutral gas temperatures found in the plasma reactor a dipole model of the excitation-emission process provides good agreement with the measured spectrum. A least-square fitting procedure comparing the model and measured emission spectra is used to determine the rotation temperature. In this poster the first EBF measurements of gas heating in an ICP reactor at different gas pressures (20, 50 mTorr) and plasma source input powers (250, 500, 1000W) are reported and compared with the plasma emission data by using a insertable optical fiber.

  10. Laser Thomson scattering measurements of electron temperature and density in a hall-effect plasma

    NASA Astrophysics Data System (ADS)

    Washeleski, Robert L.

    Hall-effect thrusters (HETs) are compact electric propulsion devices with high specific impulse used for a variety of space propulsion applications. HET technology is well developed but the electron properties in the discharge are not completely understood, mainly due to the difficulty involved in performing accurate measurements in the discharge. Measurements of electron temperature and density have been performed using electrostatic probes, but presence of the probes can significantly disrupt thruster operation, and thus alter the electron temperature and density. While fast-probe studies have expanded understanding of HET discharges, a non-invasive method of measuring the electron temperature and density in the plasma is highly desirable. An alternative to electrostatic probes is a non-perturbing laser diagnostic technique that measures Thomson scattering from the plasma. Thomson scattering is the process by which photons are elastically scattered from the free electrons in a plasma. Since the electrons have thermal energy their motion causes a Doppler shift in the scattered photons that is proportional to their velocity. Like electrostatic probes, laser Thomson scattering (LTS) can be used to determine the temperature and density of free electrons in the plasma. Since Thomson scattering measures the electron velocity distribution function directly no assumptions of the plasma conditions are required, allowing accurate measurements in anisotropic and non-Maxwellian plasmas. LTS requires a complicated measurement apparatus, but has the potential to provide accurate, non-perturbing measurements of electron temperature and density in HET discharges. In order to assess the feasibility of LTS diagnostics on HETs non-invasive measurements of electron temperature and density in the near-field plume of a Hall thruster were performed using a custom built laser Thomson scattering diagnostic. Laser measurements were processed using a maximum likelihood estimation method

  11. Measurement of the Electron-Ion Temperature Relaxation Rate in a Dense Plasma

    NASA Astrophysics Data System (ADS)

    Taccetti, J. M.; Shurter, R. P.; Goodwin, P. M.; Benage, J. F., Jr.

    2008-11-01

    Current theoretical approaches to temperature relaxation, which can be categorized as binary-collision and many-body approaches, disagree. Existing experimental evidence infers a lower relaxation rate compared to the binary-collision approach, but is insufficient to determine which approach is correct. We present the most recent results from an experiment aimed at obtaining the temperature relaxation rate between ions and electrons in a dense, strongly coupled plasma by directly measuring the temperature of each component. The plasma is formed by heating a gas jet with a 10 ps laser pulse. The electrons are preferentially heated by the short pulse laser (Te 100 eV), while the ions, after undergoing very rapid (sub-ps time-scale) disorder-induced heating, should only reach a temperature of 10-15 eV. This results in a strongly coupled ion plasma with an ion-ion coupling parameter γii 3-5. We plan to measure the electron and ion temperatures of the resulting plasma independently during and after heating, using collective Thomson scattering for electrons and a high-resolution x-ray spectrometer for the ions (measuring Doppler-broadened absorption lines).

  12. Temporal evolution of electron density and temperature in capillary discharge plasmas

    SciTech Connect

    Oh, Seong Y.; Kang, Hoonsoo; Uhm, Han S.; Lee, In W.; Suk, Hyyong

    2010-05-15

    Time-resolved spectroscopic measurements of a capillary discharge plasma of helium gas were carried out to obtain detailed information about dynamics of the discharge plasma column, where the fast plasma dynamics is determined by the electron density and temperature. Our measurements show that the electron density of the capillary plasma column increases sharply after gas breakdown and reaches its peak of the order of 10{sup 18} cm{sup -3} within less than 100 ns, and then it decreases as time goes by. The result indicates that a peak electron density of 2.3x10{sup 18} cm{sup -3} occurs about 65 ns after formation of the discharge current, which is ideal for laser wakefield acceleration experiments reported by Karsch et al. [New J. Phys. 9, 415 (2007)].

  13. Temporal evolution of electron density and temperature in capillary discharge plasmas

    NASA Astrophysics Data System (ADS)

    Oh, Seong Y.; Uhm, Han S.; Kang, Hoonsoo; Lee, In W.; Suk, Hyyong

    2010-05-01

    Time-resolved spectroscopic measurements of a capillary discharge plasma of helium gas were carried out to obtain detailed information about dynamics of the discharge plasma column, where the fast plasma dynamics is determined by the electron density and temperature. Our measurements show that the electron density of the capillary plasma column increases sharply after gas breakdown and reaches its peak of the order of 1018 cm-3 within less than 100 ns, and then it decreases as time goes by. The result indicates that a peak electron density of 2.3×1018 cm-3 occurs about 65 ns after formation of the discharge current, which is ideal for laser wakefield acceleration experiments reported by Karsch et al. [New J. Phys. 9, 415 (2007)].

  14. Electron density and temperature profile diagnostics for C-2 field reversed configuration plasmas

    SciTech Connect

    Deng, B. H.; Kinley, J. S.; Schroeder, J.

    2012-10-15

    The 9-point Thomson scattering diagnostic system for the C-2 field reversed configuration plasmas is improved and the measured electron temperature profiles are consistent with theoretical expectations. Rayleigh scattering revealed a finite line width of the ruby laser emission, which complicates density calibration. Taking advantage of the plasma wobble motion, density profile reconstruction accuracy from the 6-chord two-color CO{sub 2}/HeNe interferometer data is improved.

  15. Electron energy distribution function, effective electron temperature, and dust charge in the temporal afterglow of a plasma

    SciTech Connect

    Denysenko, I. B.; Azarenkov, N. A.; Kersten, H.

    2016-05-15

    Analytical expressions describing the variation of electron energy distribution function (EEDF) in an afterglow of a plasma are obtained. Especially, the case when the electron energy loss is mainly due to momentum-transfer electron-neutral collisions is considered. The study is carried out for different EEDFs in the steady state, including Maxwellian and Druyvesteyn distributions. The analytical results are not only obtained for the case when the rate for momentum-transfer electron-neutral collisions is independent on electron energy but also for the case when the collisions are a power function of electron energy. Using analytical expressions for the EEDF, the effective electron temperature and charge of the dust particles, which are assumed to be present in plasma, are calculated for different afterglow durations. An analytical expression for the rate describing collection of electrons by dust particles for the case when the rate for momentum-transfer electron-neutral collisions is independent on electron energy is also derived. The EEDF profile and, as a result, the effective electron temperature and dust charge are sufficiently different in the cases when the rate for momentum-transfer electron-neutral collisions is independent on electron energy and when the rate is a power function of electron energy.

  16. Impact of plasma parameter on self-organization of electron temperature gradient driven turbulence

    NASA Astrophysics Data System (ADS)

    Kawai, C.; Idomura, Y.; Maeyama, S.; Ogawa, Y.

    2017-04-01

    Self-organization in the slab electron temperature gradient driven (ETG) turbulence is investigated based on gyrokinetic simulations and the Hasegawa-Mima (HM) equation. The scale and the anisotropy of self-organized turbulent structures vary depending on the Rhines scale and the characteristic scale given by the adiabatic response term in the HM equation. The former is determined by competition between the linear wave dispersion and the nonlinear turbulent cascade, while the latter is given as the scale, at which the turbulent cascade is impeded. These scales are controlled by plasma parameters such as the density and temperature gradient, and the temperature ratio of ion to electron. It is found that depending on the plasma parameters, the ETG turbulence shows either isotropic turbulence or zonal flows, which give significantly different transport levels. Although the modulational instability excites zonal modes regardless of the plasma parameters, the final turbulent structure is determined by the self-organization process.

  17. Electron beam fluorescence temperature measurements of N2 in a semiconductor plasma reactor

    NASA Astrophysics Data System (ADS)

    Shimada, M.; Cattolica, R.; Tynan, G. R.

    2004-03-01

    The rotational temperature of nitrogen molecules in inductively coupled plasma (ICP) discharge has been measured using the electron beam fluorescence (EBF) technique. The neutral gas temperature is an important parameter in understanding the energy balance and neutral radical uniformity in plasma processing. The EBF technique has been used to study rarefied flows, but has not been applied previously to characterize a semiconductor plasma reactor. In this work an electron beam was integrated into an inductively coupled semiconductor plasma reactor, and was used to excite neutral nitrogen molecules from the N2X 1Σg+ state into the excited molecular ion N2+B 2Σu+ state. The electron beam excitation process maps the rotational population distribution of the original ground state into the excited molecular ion state following a dipole model with ΔK=+/-1. The rotational temperature, which is thought to be equivalent to the neutral gas translational temperature under plasma reactor conditions, can be determined from the rotational intensity distribution of the fluorescence spectrum from the N2+B 2Σu+ state. For the range of neutral gas temperatures found in the plasma reactor a dipole model of the excitation-emission process provides good agreement with the measured spectrum. A least-square fitting procedure comparing the model and measured emission spectra is used to determine the rotation temperature. In this article the first EBF measurements of gas heating in an ICP reactor at different gas pressures (20, 50 mTorr) and plasma source input powers (250, 500, and 1000 W) are reported. .

  18. Measuring the electron temperature by optical emission spectroscopy in two temperature plasmas at atmospheric pressure: A critical approach

    SciTech Connect

    Yanguas-Gil, A.; Cotrino, J.; Gonzalez-Elipe, A. R.

    2006-02-01

    The measurement of the electron mean kinetic energy by identifying the electron temperature and the excitation temperature obtained by optical emission spectroscopy is theoretically studied for two temperature argon plasmas at atmospheric pressure. Using a 32-level collisional radiative model in which both electron impact and argon-impact inelastic collisions are taken into account, it has been found that under certain conditions the argon inelastic collisions may cause a decrease of the argon excitation temperature so that the relation T{sub e}>T{sub exc}>T{sub 0} is satisfied. This inequality also appears when electron losses due to diffusion are important and the electron density is lower than its equilibrium value.

  19. Electron density and temperature diagnostics for atmospheric pressure plasmas using continuum radiation

    NASA Astrophysics Data System (ADS)

    Park, Sanghoo; Moon, Se Youn; Choe, Wonho

    2014-10-01

    Information on electrons is particularly valuable because most of the important plasma reactions are governed by electron kinetics. However, diagnostics of electron density (ne) and temperature (Te) of low temperature atmospheric pressure plasmas is still challenging although there are some advanced diagnostics available such as laser Thomson scattering or optical emission spectroscopy combined with complex plasma equilibrium models. In this work, we report a simple spectroscopic diagnostic method with high temporal and spatial resolution based on continuum radiation in the UV and visible range for ne and Te. Together with the basic principle for the diagnostics including electron-atom bremsstrahlung (or neutral bremsstrahlung) and hydrogen radiative dissociation continuum, some experimental results in several argon and helium atmospheric pressure plasmas will be presented. In a typical argon 13.56 MHz parallel plate capacitive discharge, the measured values are Te = 2.5 eV and ne = 0.7--1.1 × 1012 cm-3 at Prf = 110--200 W. Two-dimensional Te profile of an Ar pulsed plasma jet using a DSLR camera and this diagnostics will also be shown.

  20. Spectral measurements of electron temperature in nonequilibrium highly ionized He plasma

    NASA Astrophysics Data System (ADS)

    Korshunov, O. V.; Chinnov, V. F.; Kavyrshin, D. I.; Ageev, A. G.

    2016-11-01

    It has been experimentally shown that highly ionized He arc plasma does not achieve local thermodynamic equilibrium expected for plasmas with electron concentrations above 1 × 1016 cm-3 like argon plasma. We have found that the reason for this deviation is strong nonisotropy of plasma. Triple electron recombination with temperatures of 2.5-3 eV is almost absent. Charged particles move from the arc (r = 1 mm) to chamber walls due to ambipolar diffusion creating ionization nonequilibrium over the excited states rendering Boltzmann distribution and Saha equation inapplicable for determining electron temperature. A method for determining electron temperature is suggested that is based on using the relative intensities of the atomic and ion lines. Its advantage lies in an energy gap between these lines’ states over 50 eV that reduces the influence of nonequilibrium on the result. This influence can be taken into account if the ionization energies of emitting states of atom and ion have close values. The suggested method can be expanded for any media including those with dimensional nonisotropy that have both atomic and ion lines in their emission spectra.

  1. Improved electron collisional line broadening for low-temperature ions and neutrals in plasma modeling

    DOE PAGES

    Johns, H. M.; Kilcrease, D. P.; Colgan, J.; ...

    2015-09-29

    In this study, electron collisional broadening of observed spectral lines depends on plasma electron temperature and density. Including this effect in models of measured spectra is necessary to determine plasma conditions; however, computational limits make accurate line broadening treatments difficult to implement in large-scale plasma modeling efforts. In this paper, we report on improvements to the treatment of electron collisional line broadening and illustrate this with calculations using the Los Alamos ATOMIC code. We implement the Dimitrijevic and Konjevic modified semi-empirical model Dimitrijevic and Konjevic (1986 Astron. and Astrophy. 163 297 and 1987 Astron. Astrophys. 172 345), which we amendmore » by employing oscillator strengths from Hartree–Fock calculations. This line broadening model applies to near-neutral plasmas with electron temperatures of Te ~ 1 eV and electron densities of Ne ~1017 cm-3. We evaluate the D.K.-inspired model against the previous hydrogenic approach in ATOMIC through comparison to NIST-rated measurements for selected neutral and singly-ionized Ca, O, Fe, and Sn lines using both fine-structure and configuration-averaged oscillator strengths. The new D.K.-inspired model is significantly more accurate than the previous hydrogenic model and we find the use of configuration-averaged oscillator strengths a good approximation for applications such as LIBS (laser induced breakdown spectroscopy), for which we demonstrate the use of the D.K.-inspired model.« less

  2. Improved electron collisional line broadening for low-temperature ions and neutrals in plasma modeling

    SciTech Connect

    Johns, H. M.; Kilcrease, D. P.; Colgan, J.; Judge, E. J.; Barefield II, J. E.; Wiens, R. C.; Clegg, S. M.

    2015-09-29

    In this study, electron collisional broadening of observed spectral lines depends on plasma electron temperature and density. Including this effect in models of measured spectra is necessary to determine plasma conditions; however, computational limits make accurate line broadening treatments difficult to implement in large-scale plasma modeling efforts. In this paper, we report on improvements to the treatment of electron collisional line broadening and illustrate this with calculations using the Los Alamos ATOMIC code. We implement the Dimitrijevic and Konjevic modified semi-empirical model Dimitrijevic and Konjevic (1986 Astron. and Astrophy. 163 297 and 1987 Astron. Astrophys. 172 345), which we amend by employing oscillator strengths from Hartree–Fock calculations. This line broadening model applies to near-neutral plasmas with electron temperatures of Te ~ 1 eV and electron densities of Ne ~1017 cm-3. We evaluate the D.K.-inspired model against the previous hydrogenic approach in ATOMIC through comparison to NIST-rated measurements for selected neutral and singly-ionized Ca, O, Fe, and Sn lines using both fine-structure and configuration-averaged oscillator strengths. The new D.K.-inspired model is significantly more accurate than the previous hydrogenic model and we find the use of configuration-averaged oscillator strengths a good approximation for applications such as LIBS (laser induced breakdown spectroscopy), for which we demonstrate the use of the D.K.-inspired model.

  3. Electron Temperature Gradient Scale Measurements in ICRF Heated Plasmas at Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Houshmandyar, Saeid; Phillips, Perry E.; Rowan, William L.; Howard, Nathaniel T.; Greenwald, Martin

    2016-10-01

    It is generally believed that the temperature gradient is a driving mechanism for the turbulent transport in hot and magnetically confined plasmas. A feature of many anomalous transport models is the critical threshold value (LC) for the gradient scale length, above which both the turbulence and the heat transport increases. This threshold is also predicted by the recent multi-scale gyrokinetic simulations, which are focused on addressing the electron (and ion) heat transport in tokamaks. Recently, we have established an accurate technique (BT-jog) to directly measure the electron temperature gradient scale length (LTe =Te / ∇T) profile, using a high-spatial resolution radiometer-based electron cyclotron emission (ECE) diagnostic. For the work presented here, electrons are heated by ion cyclotron range of frequencies (ICRF) through minority heating in L-mode plasmas at different power levels, TRANSP runs determine the electron heat fluxes and the scale lengths are measured through the BT-jog technique. Furthermore, the experiment is extended for different plasma current and electron densities by which the parametric dependence of LC on magnetic shear, safety factor and density will be investigated. This work is supported by U.S. DoE OFES, under Award No. DE-FG03-96ER-54373.

  4. Study of transport properties with relativistic ponderomotive effect in two-electron temperature plasma

    SciTech Connect

    Sen, Sonu Dubey, A.; Varshney, Meenu Asthana; Varshney, Dinesh

    2014-04-24

    In the present paper we make an analytical investigation to study transport properties with relativistic ponderomotive effect in two-electron temperature plasma. Using fluid model the two-electron temperature are introduced through relativistic ponderomotive force for the transportation of two species of electrons. Applying WKB and paraxial ray approximation the nonlinear dielectric constant and self-focusing equation is evaluated and analyzed with experimental relevance. Numerical calculations are made for different concentration of electron density (10{sup 19}−10{sup 21} per cm{sup 3}) at arbitrary values of laser intensity in the range 10{sup 18}−10{sup 21} W/cm{sup 2}. For a minimum radius depending on the initial conditions it is oscillating between a minimum and maximum value. The hot electrons leading to the increase of the on-axis transportation and favorable effect on relativistic self-focusing.

  5. Surface electronic states of low-temperature H-plasma-exposed Ge(100)

    NASA Astrophysics Data System (ADS)

    Cho, Jaewon; Nemanich, R. J.

    1992-11-01

    The surface of low-temperature H-plasma-cleaned Ge(100) was studied by angle-resolved UV-photoemission spectroscopy and low-energy electron diffraction (LEED). The surface was prepared by an ex situ preclean followed by an in situ H-plasma exposure at a substrate temperature of 150-300 °C. Auger-electron spectroscopy indicated that the in situ H-plasma clean removed the surface contaminants (carbon and oxygen) from the Ge(100) surface. The LEED pattern varied from a 1×1 to a sharp 2×1, as the substrate temperature was increased. The H-induced surface state was identified at ~5.6 eV below EF, which was believed to be mainly due to the ordered or disordered monohydride phases. The annealing dependence of the spectra showed that the hydride started to dissociate at a temperature of 190 °C, and the dangling-bond surface state was identified. A spectral shift upon annealing indicated that the H-terminated surfaces were unpinned. After the H-plasma clean at 300 °C the dangling-bond surface state was also observed directly with no evidence of H-induced states.

  6. Zakharov-Kuznetsov equation in a magnetized plasma with two temperature superthermal electrons

    SciTech Connect

    Saini, N. S. Chahal, B. S.; Bains, A. S.; Bedi, C.

    2014-02-15

    A nonlinear Zakharov-Kuznetsov (ZK) equation for ion-acoustic solitary waves (IASWs) in a magnetized plasmas containing kappa distributed cold and hot electrons is derived by using reductive perturbation method. From the solution of ZK equation, the characteristics of IASWs have been studied under the influence of various plasma parameters. Existence domain of physical parameters is determined. It has been observed that the present plasma system supports the existence of both positive as well as negative potential solitons. The combined effects of cold to hot electron temperature ratio (σ), density ratio of cold electrons to ions (f), superthermality of cold and hot electrons (κ{sub c},κ{sub h}), strength of magnetic field (via Ω{sub i}), and obliqueness (θ) significantly influence the profile of IASWs. The physical parameters play a great role to modify the width and amplitude of the solitary structures. The stability analysis is also presented in this investigation and parametric range is determined to check the presence of stable and unstable solitons. The findings of this study are important to the physics of electrostatic wave structures in the Saturn's magnetosphere where two temperature electrons with kappa distribution exist.

  7. Electron density and temperature diagnostics in laser-induced hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Gautam, G.; Parigger, C. G.

    2017-02-01

    Laser-induced optical breakdown is achieved by using Q-switched, Nd:YAG radiation focused into ultra-high-purity (UHP) hydrogen gas at a pressure of 1.08 ± 0.03 × 105 Pa inside a cell. The plasma emission spectra are dispersed by a Czerny-Turner type spectrometer and detected with an intensified charge-coupled device (ICCD). Stark-broadened hydrogen Balmer series H α and Hβ line profiles are used as a spectroscopic tool for the determination of electron density and excitation temperature. Spatial variation of electron density and temperature at 0.40 µs are extracted from the recorded intensities of H α and Hβ lines. Temporal variations of electron density and excitation temperature are also presented for the time delay range of 0.15 µs to 1.4 µs.

  8. Theory of coupled whistler-electron temperature gradient mode in high beta plasma: Application to linear plasma device

    SciTech Connect

    Singh, S. K.; Awasthi, L. M.; Singh, R.; Kaw, P. K.; Jha, R.; Mattoo, S. K.

    2011-10-15

    This paper presents a theory of coupled whistler (W) and electron temperature gradient (ETG) mode using two-fluid model in high beta plasma. Non-adiabatic ion response, parallel magnetic field perturbation ({delta}B{sub z}), perpendicular magnetic flutter ({delta}B{sub perpendicular}), and electron collisions are included in the treatment of theory. A linear dispersion relation for whistler-electron temperature gradient (W-ETG) mode is derived. The numerical results obtained from this relation are compared with the experimental results observed in large volume plasma device (LVPD) [Awasthi et al., Phys. Plasma 17, 42109 (2010)]. The theory predicts that the instability grows only where the temperature gradient is finite and the density gradient flat. For the parameters of the experiment, theoretically estimated frequency and wave number of W-ETG mode match with the values corresponding to the peak in the power spectrum observed in LVPD. By using simple mixing length argument, estimated level of fluctuations of W-ETG mode is in the range of fluctuation level observed in LVPD.

  9. Magnetic piston model for higher ion charge and different electron and ion plasma temperatures

    SciTech Connect

    Bogatu, I. N.

    2013-05-15

    A new formula for the magnetic piston model, which explicitly describes how the momentum imparted to the ions by the magnetic pressure depends not only on the ion mass but also on the ion charge, as well as, on the plasma electron and ion temperatures, is derived following Rosenbluth's classical particle-field self-consistent plane approximation analytic calculation. The formula presented in this paper has implications in explaining the experimentally observed separation of the ions of different species and charges by the magnetic field penetrating the plasma and specularly reflecting them.

  10. Measurements of Electron Density and Temperature of Micropinch Plasma Formed in Vacuum-Spark Discharge

    NASA Astrophysics Data System (ADS)

    Mohammad, Nisar; Koshelev, K. N.; Antsiferov, P. S.; Kunze, H. J.

    2000-10-01

    The parameters of micropinches formed in vacuum-spark discharge are investigated spectroscopically. Single shot x-ray spectra of He-like S, Cl, Ca, Cr, Fe and H-like Ca ions are recorded using crystal spectrograph. The comparison of experimental spectrum with the corresponding theoretical one, generated by codes FLY and FLYSPEC is used to determine the electron density ne and temperature Te of micropinch plasma.

  11. Oblique ion-acoustic cnoidal waves in two temperature superthermal electrons magnetized plasma

    SciTech Connect

    Panwar, A. Ryu, C. M.; Bains, A. S.

    2014-12-15

    A study is presented for the oblique propagation of ion acoustic cnoidal waves in a magnetized plasma consisting of cold ions and two temperature superthermal electrons modelled by kappa-type distributions. Using the reductive perturbation method, the nonlinear Korteweg de-Vries equation is derived, which further gives the solutions with a special type of cnoidal elliptical functions. Both compressive and rarefactive structures are found for these cnoidal waves. Nonlinear periodic cnoidal waves are explained in terms of plasma parameters depicting the Sagdeev potential and the phase curves. It is found that the density ratio of hot electrons to ions μ significantly modifies compressive/refractive wave structures. Furthermore, the combined effects of superthermality of cold and hot electrons κ{sub c},κ{sub h}, cold to hot electron temperature ratio σ, angle of propagation and ion cyclotron frequency ω{sub ci} have been studied in detail to analyze the height and width of compressive/refractive cnoidal waves. The findings in the present study could have important implications in understanding the physics of electrostatic wave structures in the Saturn's magnetosphere where two temperature superthermal electrons are present.

  12. Effects of Anomalous Electron Cross-Field Transport in a Low Temperature Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Raitses, Yevgeny

    2014-10-01

    The application of the magnetic field in a low pressure plasma can cause a spatial separation of low and high energy electrons. This so-called magnetic filter effect is used for many plasma applications, including ion and neutral beam sources, plasma processing of semiconductors and nanomaterials, and plasma thrusters. In spite of successful practical applications, the magnetic filter effect is not well understood. In this work, we explore this effect by characterizing the electron and ion energy distribution functions in a plasma column with crossed electric and magnetic fields. Experimental results revealed a strong dependence of spatial variations of plasma properties on the gas pressure. For xenon and argon gases, below ~ 1 mtorr, the increase of the magnetic field leads to a more uniform profile of the electron temperature. This surprising result is due to anomalously high electron cross-field transport that causes mixing of hot and cold electrons. High-speed imaging and probe measurements revealed a coherent structure rotating in E cross B direction with frequency of a few kHz. Theory and simulations describing this rotating structure has been developed and points to ionization and electrostatic instabilities as their possible cause. Similar to spoke oscillations reported for Hall thrusters, this rotating structure conducts the large fraction of the cross-field current. The use of segmented electrodes with an electrical feedback control is shown to mitigate these oscillations. Finally, a new feature of the spoke phenomenon that has been discovered, namely a sensitive dependence of the rotating oscillations on the gas pressure, can be important for many applications. This work was supported by DOE Contract DE-AC02-09CH11466.

  13. Electrostatic wave structures in a magnetized superthermal plasma with two-temperature electrons

    SciTech Connect

    Shahmansouri, M.; Alinejad, H.

    2013-08-15

    The linear and nonlinear excitation of arbitrary amplitude ion-acoustic (IA) solitary waves in a magnetized plasma comprising two-temperature electrons and cold ions are studied. The oblique propagation properties of two possible modes (in the linear regime) are investigated. It is found that the electron superthermality reduces the phase velocities of both modes, whereas obliqueness leads to an increase in the separation between two modes. In the nonlinear regime, an energy-like equation describes the evolution of IA solitary waves in the present model. The combined effects of the electron superthermality, magnitude of magnetic field, obliqueness and electron population are incorporated in the study of the existence domain of solitary waves and the soliton characteristics. It is shown that the small values of the hot electron population shift the permitted interval of Mach number to the lower values. Both compressive and rarefactive solitary structures are found to exist in the presence of two temperature electrons. The present investigation contributes to the physics of electrostatic wave structures in Saturn's magnetosphere in which two temperature electrons with kappa distribution exist.

  14. The Jupiter hot plasma torus - Observed electron temperature and energy flows

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1981-01-01

    The detection of the optical emission /O I/ 6300 A (8 + or - 4 R) and /S III/ 6312 A (48 + or - 5 R) is reported. It is noted that these emissions are indicators of the ion source morphology and the plasma physical state and that the S III emitters have a kinetic temperature of approximately 10 to the 6th K. When combined with observations of UV lines from the same species, the optical measurements separately imply effective electron temperatures for radiative processes that are mutually consistent (approximately 50,000 K).

  15. Dust Acoustic Solitary Waves in Dusty Plasma with Trapped Electrons Having Different Temperature Nonthermal Ions

    NASA Astrophysics Data System (ADS)

    Deka, Manoj Kr.

    2016-12-01

    In this report, a detailed investigation on the study of dust acoustics solitary waves solution with negatively dust charge fluctuation in dusty plasma corresponding to lower and higher temperature nonthermal ions with trapped electrons is presented. We consider temporal variation of dust charge as a source of dissipation term to derive the lower order modified Kadomtsev-Petviashvili equation by using the reductive perturbation technique. Solitary wave solution is obtained with the help of sech method in presence of trapped electrons and low (and high) temperature nonthermal ions. Both nonthermality of ions and trapped state of the electrons are found to have an imperative control on the nonlinear coefficient, dissipative coefficient as well as height of the wave potential.

  16. Anode heat transfer for a flowing argon plasma at elevated electron temperature.

    NASA Technical Reports Server (NTRS)

    Bose, T. K.

    1972-01-01

    Theoretical investigation of heat transfer from a preionized gaseous plasma flowing over an anode surface at an elevated electron temperature in the presence of an electric field normal to the surface. A laminar boundary layer is considered in which only the velocity profile is locally similar and fluid properties are assumed to change uniformly in the gas flow direction. Results obtained by an approximation method show that for moderate current densities, the velocity and temperature distributions are insensitive to current. In addition, the effect of elevated electron temperature is negligible on convective heat transfer, but is significant for the overall heat transfer due to the enthalpy transport by current. Total heat flux to the anode is obtained by evaluating the Nusselt number and adding terms due to the potential drop in the sheath and the surface work function.

  17. The LXCat project: Electron scattering cross sections and swarm parameters for low temperature plasma modeling

    NASA Astrophysics Data System (ADS)

    Pancheshnyi, S.; Biagi, S.; Bordage, M. C.; Hagelaar, G. J. M.; Morgan, W. L.; Phelps, A. V.; Pitchford, L. C.

    2012-04-01

    LXCat is a dynamic, open-access, website for collecting, displaying, and downloading ELECtron SCATtering cross sections and swarm parameters (mobility, diffusion coefficient, reaction rates, etc.) required for modeling low temperature, non-equilibrium plasmas. Contributors set up individual databases, and the available databases, indicated by the contributor's chosen title, include mainly complete sets of electron-neutral scattering cross sections, although the option for introducing partial sets of cross sections exists. A database for measured swarm parameters is also part of LXCat, and this is a growing activity. On-line tools include options for browsing, plotting, and downloading cross section data. The electron energy distribution functions (edfs) in low temperature plasmas are in general non-Maxwellian, and LXCat provides an option for execution of an on-line Boltzmann equation solver to calculate the edf in homogeneous electric fields. Thus, the user can obtain electron transport and rate coefficients (averages over the edfs) in pure gases or gas mixtures over a range of values of the reduced electric fields strength, E/N, the ratio of the electric field strength to the neutral density, using cross sections from the available databases. New contributors are welcome and anyone wishing to create a database and upload data can request a username and password. LXCat is part of a larger, community-wide effort aimed at collecting, evaluating, and sharing data relevant to modeling low temperature plasmas. To illustrate the utility of LXCat in this context, we compare electron swarm parameters in argon calculated using the different compilations of cross sections presently available on LXCat. These compilations include quite different groupings of excited states, yet lead to swarm parameters in good agreement. LXCat is available at http://www.lxcat.laplace.univ-tlse.fr.

  18. Secondary Electron Emission Properties of Plasma Facing Ceramic Materials at High Temperatures

    NASA Astrophysics Data System (ADS)

    Raitses, Yevgeny; Dourbal, Paul; Spektor, Rostislav

    2015-11-01

    The plasma-wall interaction in the presence of strong secondary electron emission (SEE) has been studied theoretically and experimentally both as a basic phenomenon and in relation to numerous plasma applications such as, for example, fusion devices and Hall thrusters. Herein, we report on SEE measurements for boron nitride (BN) ceramics, which are commonly used as channel wall materials for Hall thrusters. Measurements were conducted for BN ceramics of three different grades with different fractions (0, 1% and 40%) and phases of different binder additions (calcium borate, silicon oxide) and as a function of the sample temperature relevant to the thruster operation (about 600K). For all three grades, the energy at which the yield equals to 1 at room temperature was measured to be near 40 V. This result is in agreement with previous measurements. At the elevated temperature, the yield was slightly different for these ceramics, but lower than at the room temperature. This temperature effect was not as strong as measured in. Analysis of these results and their implication on plasma-surface interactions in Hall thrusters and other related devices are presented. This work was partially supported by the Aerospace Corporation and by DOE contract DE-AC02-09CH11466.

  19. High temperature electrons exhausted from rf plasma sources along a magnetic nozzle

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazunori; Akahoshi, Hikaru; Charles, Christine; Boswell, Rod W.; Ando, Akira

    2017-08-01

    Two dimensional profiles of electron temperature are measured inside and downstream of a radiofrequency plasma thruster source having a magnetic nozzle and being immersed in vacuum. The temperature is estimated from the slope of the fully swept I-V characteristics of a Langmuir probe acquired at each spatial position and with the assumption of a Maxwellian distribution. The results show that the peripheral high temperature electrons in the magnetic nozzle originate from the upstream antenna location and are transported along the "connecting" magnetic field lines. Two-dimensional measurements of electron energy probability functions are also carried out in a second simplified laboratory device consisting of the source contiguously connected to the diffusion chamber: again the high temperature electrons are detected along the magnetic field lines intersecting the wall at the antenna location, even when the antenna location is shifted along the main axis. These results demonstrate that the peripheral energetic electrons in the magnetic nozzle mirror those created in the source tube.

  20. Ion acoustic kinetic Alfvén rogue waves in two temperature electrons superthermal plasmas

    NASA Astrophysics Data System (ADS)

    Kaur, Nimardeep; Saini, N. S.

    2016-10-01

    The propagation properties of ion acoustic kinetic Alfvén (IAKA) solitary and rogue waves have been investigated in two temperature electrons magnetized superthermal plasma in the presence of dust impurity. A nonlinear analysis is carried out to derive the Korteweg-de Vries (KdV) equation using the reductive perturbation method (RPM) describing the evolution of solitary waves. The effect of various plasma parameters on the characteristics of the IAKA solitary waves is studied. The dynamics of ion acoustic kinetic Alfvén rogue waves (IAKARWs) are also studied by transforming the KdV equation into nonlinear Schrödinger (NLS) equation. The characteristics of rogue wave profile under the influence of various plasma parameters (κc, μc, σ , θ) are examined numerically by using the data of Saturn's magnetosphere (Schippers et al. 2008; Sakai et al. 2013).

  1. Plasma Temperatures at Mars

    NASA Astrophysics Data System (ADS)

    Mayyasi-Matta, Majd; Mendillo, M.; Galand, M.; Moore, L.; Withers, P.

    2013-10-01

    Ion and electron temperatures in the ionosphere of Mars affect plasma densities. These quantities vary with altitude and time of day. Modeling results are used to interpret existing measurements and to support anticipated MAVEN measurements. A 1D fluid model of the Martian ionosphere has been coupled to a kinetic supra-thermal electron transport model in order to self-consistently calculate ion and electron densities and temperatures. The models include diurnal variations, revealing hundreds of Kelvin changes in dayside electron and ion temperatures at fixed altitude. The models treat each ion species separately, revealing hundreds of Kelvin differences between H+ and O2+ temperatures. Consistent with previous studies using single-ion plasma, solar EUV heating alone is insufficient to heat the thermal electrons and ion species to observed temperatures, indicating the presence of additional heating sources.

  2. Spectral evolution of soft x-ray emission from optically thin, high electron temperature platinum plasmas

    NASA Astrophysics Data System (ADS)

    Hara, Hiroyuki; Ohashi, Hayato; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Sasaki, Akira; Suzuki, Chihiro; Tamura, Naoki; Sakaue, Hiroyuki A.; Kato, Daiji; Murakami, Izumi; Higashiguchi, Takeshi; LHD Experiment Group

    2017-08-01

    The soft x-ray spectra of heavy element plasmas are frequently dominated by unresolved transition array (UTA) emission. We describe the spectral evolution of an intense UTA under optically thin conditions in platinum plasmas. The UTA was observed to have a peak wavelength around 4.6 nm at line-of-sight averaged electron temperatures less than 1.4 keV at electron densities of (2.5-7.5) × 1013 cm-3. The UTA spectral structure was due to emission from 4d-4f transitions in highly charged ions with average charge states of q = 20-40. A numerical simulation successfully reproduced the observed spectral behavior.

  3. Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures

    SciTech Connect

    Lopez, Rodrigo A.; Munoz, Victor; Asenjo, Felipe A.; Alejandro Valdivia, J.

    2012-08-15

    The nonlinear evolution of a circularly polarized electromagnetic wave in an electron-positron plasma propagating along a constant background magnetic field is considered, by studying its parametric decays. Relativistic effects, of the particle motion in the wave field and of the plasma temperature, are included to obtain the dispersion relation of the decays. The exact dispersion relation of the pump wave has been previously calculated within the context of a relativistic fluid theory and presents two branches: an electromagnetic and an Alfven one. We investigate the parametric decays for the pump wave in these two branches, including the anomalous dispersion zone of the Alfven branch where the group velocity is negative. We solve the nonlinear dispersion relation for different pump wave amplitudes and plasma temperatures, finding various resonant and nonresonant wave couplings. We are able to identify these couplings and study their behavior as we modify the plasma parameters. Some of these couplings are suppressed for larger amplitudes or temperatures. We also find two kinds of modulational instabilities, one involving two sideband daughter waves and another involving a forward-propagating electroacoustic mode and a sideband daughter wave.

  4. Small amplitude electron-acoustic double layers and solitons in fully relativistic plasmas of two-temperature electrons

    SciTech Connect

    Lee, Nam C.

    2009-04-15

    A Korteweg-de Vries (KdV) equation for fully relativistic one dimensional plasmas of arbitrarily large streaming speed and temperature is derived by using the reductive perturbation method. For plasmas with more than two species of particles, the coefficient representing quadratic nonlinearity in KdV can vanish at critical values of certain parameters. To describe the nonlinear evolution at this critical parameter, a modified KdV (mKdV) equation that contains a cubic nonlinear term is obtained. Furthermore, a mixed mKdV equation pertaining to parameters in the vicinity of the critical values is also derived, in which the quadratic and cubic nonlinearities are both present. As an illustration of the results, the mixed mKdV equation is applied to a plasma comprised of cold ions and electrons having cold (T=0) and finite temperature components. For warm temperature T<electron-acoustic nonlinear waves in the shape of double layer (kink) and solitary waves can exist, which have phase speed {radical}(3T/(4+{alpha})m{sub e}) in the rest frame of plasma, where {alpha} is the polytropic index of the equation of state of the warm electrons. The thickness of the transitional layer of the kink structure is of the order of Debye length {lambda}{sub D}. For extremely high temperature T>>m{sub e}c{sup 2}, it is also found that double layer and soliton-type solutions can exist with phase speed {radical}({alpha}-1)c, which is equal to the well known relativistic sound speed c/{radical}(3) for {alpha}=4/3. The thickness of the transition layer scales as {delta}{approx}T{sup -1/4}, which is different from the T<

  5. Measurements of hot-electron temperature in laser-irradiated plasmas

    NASA Astrophysics Data System (ADS)

    Solodov, A. A.; Yaakobi, B.; Edgell, D. H.; Follett, R. K.; Myatt, J. F.; Sorce, C.; Froula, D. H.

    2016-10-01

    In a recently published work [Yaakobi et al., Phys. Plasmas 19, 012704 (2012)] we reported on measuring the total energy of hot electrons produced by the interaction of a nanosecond laser with planar CH-coated molybdenum targets, using the Mo Kα emission. The temperature of the hot electrons in that work was determined by the high-energy bremsstrahlung [hard X-ray (HXR)] spectrum measured by a three-channel fluorescence-photomultiplier HXR detector (HXRD). In the present work, we replaced the HXRD with a nine-channel image-plate (IP)-based detector (HXIP). For the same conditions (irradiance of the order of 1014 W/cm2; 2-ns pulses), the measured temperatures are consistently lower than those measured by the HXRD (by a factor ˜1.5 to 1.7). We supplemented this measurement with three experiments that measure the hot-electron temperature using Kα line-intensity ratios from high-Z target layers, independent of the HXR emission. These experiments yielded temperatures that were consistent with those measured by the HXIP. We showed that the thermal X-ray radiation must be included in the derivation of total energy in hot electrons (Ehot), and that this makes Ehot only weakly dependent on hot-electron temperature. For a given X-ray emission in the inertial confinement fusion compression experiments, this result would lead to a higher total energy in hot electrons, but preheating of the compressed fuel may be lower because of the reduced hot-electron range.

  6. Electron capture and excitation processes in collisions of H+ with H in finite-temperature quantum plasmas

    NASA Astrophysics Data System (ADS)

    Zhao, G. P.; Liu, L.; Wang, J. G.; Janev, R. K.

    2017-10-01

    Electron capture and excitation processes in H+-H collisions imbedded in warm dense quantum plasmas are studied by the two-center atomic orbital close-coupling (TC-AOCC) method in the energy range 1-200 keV. The screened potential which is used to describe the interaction between charged particles incorporates the quantum electron degeneracy, exchange-correlation and finite-temperature gradient correlation effects. The total and state-selective electron capture and excitation cross-sections for this collision system with this potential are calculated in a wide range of plasma densities and temperatures. It is demonstrated that the screening of Coulomb interactions affects the collision dynamics and the magnitude and energy behavior of the excitation and electron capture cross-sections. The results at very low and high temperatures are also compared with those obtained for zero-temperature quantum plasmas and Debye plasmas, respectively.

  7. Electron Temperature and Density in Local Helicity Injection and High betat Plasmas

    NASA Astrophysics Data System (ADS)

    Schlossberg, David J.

    Tokamak startup in a spherical torus (ST) and an ST-based fusion nuclear science facility can greatly benefit from using non-inductive methods. The Pegasus Toroidal Experiment has developed a non-inductive startup technique using local helicity injection (LHI). Electron temperature, T e(r), and density, ne( r), profiles during LHI are unknown. These profiles are critical for understanding both the physics of the injection and relaxation mechanisms, as well as for extrapolating this technique to larger devices. A new Thomson scattering system has been designed, installed, and used to characterize Te(r, t) and ne(r, t) during LHI. The diagnostic leverages new technology in image intensified CCD cameras, high-efficiency diffraction gratings, and reliable Nd:YAG lasers. Custom systems for stray light mitigation, fast shuttering, and precision timing have been developed and implemented. The overall system provides a low-maintenance, economic, and effective means to explore novel physics regimes in Pegasus. Electron temperature and density profiles during LHI have been measured for the first time. Results indicate Te(r) peaked in the core of plasmas, and sustained while plasmas are coupled to injection drive. Electron densities also peak near the core of the tokamak, up to local values of n e ˜ 1.5 x 1019 m -3. A comparison of Te( r, t) has been made between discharges with dominant drive voltage from induction versus helicity injection. In both cases Te ( r, t) profiles remain peaked, with values for Te ,max > 150 eV in dominantly helicity-driven plasmas using high-field side LHI. Sustained values of betat ˜ 100% have been demonstrated in a tokamak for the first time. Plasmas are created and driven entirely non-solenoidally, and exhibit MHD stability. Measured temperature and density profiles are used to constrain magnetic equilibrium reconstructions, which calculate 80% < betat < 100% throughout a toroidal field ramp-down. For a continued decrease in the toroidal

  8. Electron kinetic effects on interferometry and polarimetry in high temperature fusion plasmas

    NASA Astrophysics Data System (ADS)

    Mirnov, V. V.; Brower, D. L.; Den Hartog, D. J.; Ding, W. X.; Duff, J.; Parke, E.

    2013-11-01

    At anticipated high electron temperatures in ITER, the effects of electron thermal motion on phase measurements made by the toroidal interferometer/polarimeter (TIP) and poloidal polarimeter (PoPola) diagnostics will be significant and must be precisely treated or the measurement accuracy will fail to meet the specified requirements for ITER operation. We calculate electron thermal corrections to the interferometric phase and polarization state of an electromagnetic wave propagating along tangential and poloidal chords (Faraday and Cotton-Mouton polarimetry) and incorporate them into the Stokes vector equation for evolution of polarization. Although these corrections are small at electron temperatures Te ≃ 1 keV, they become sizable at Te ⩾ 10 keV. The precision of the previous lowest order linear in the τ = Te/mec2 model may be insufficient; we present a more precise model with τ2-order corrections to satisfy the high accuracy required for ITER TIP and PoPola diagnostics. Proper treatment of temperature effects will ensure more accurate interpretation of interferometric and polarimetric measurements in fusion devices like ITER and DEMO. The use of precise analytic expressions is especially important for burning plasmas where various interferometric techniques will be used for direct real time feedback control of device operations with time resolution ˜1 ms to regulate the rate of the thermonuclear burn and monitor/control the safety factor profile.

  9. A new emissive-probe method for electron temperature measurement in radio-frequency plasmas

    SciTech Connect

    Kusaba, Kouta; Shindo, Haruo

    2007-12-15

    A new method to measure electron temperature by an emissive probe has been proposed. The method is based on measurement of the functional relationship between the floating potential and the heating voltage of emissive probe. From the measured data of the floating potential change as a function of the heating voltage, the electron temperature could be determined by comparing with the theoretical curve obtained under the assumption of Maxwellian distribution. The overall characteristic of the floating potential change could be explained as a function of the heating voltage. The electron temperatures obtained by the present method were consistent with those measured by the rf-compensated Langmuir probe within the error. These experimental verifications were made in the electron density range of 2.6x10{sup 11}-2.8x10{sup 12} cm{sup -3}. It was stressed that the present method is advantageous in that the probe is operated in a floating condition, hence applicable to plasmas produced in an insulated container.

  10. Self-focusing of coaxial electromagnetic beams in a plasma with electron temperature dependent electron-ion recombination coefficient

    NASA Astrophysics Data System (ADS)

    Misra, Shikha; Sodha, M. S.; Mishra, S. K.

    2017-02-01

    An analytical formulation, describing the propagation of multiple coaxial Gaussian electromagnetic (em) beams in a self-formed plasma channel with dominant collisional nonlinearity has been developed; the generation/recombination of high energy plasma particles has been considered as an additional source of plasma non-linearity in addition to Ohmic heating. Well versed paraxial approach in the vicinity of the intensity maximum has been adopted to solve the wave equation and examine the non-linear propagation of em beams while the dielectric function in the presence of the em field is determined from the balance of partial pressure gradient of electron/ion gas with the space charge field and energy balance of plasma particles. On the basis of the analysis the influence of this novel non-linearity on the propagation features like electron temperature, dielectric function and critical curves are derived numerically and graphically presented. The inclusion of this novel nonlinearity results in reduced focusing effect. The three regime characteristic features viz. oscillatory focusing/defocusing and steady divergence of beam propagation have also been worked out.

  11. Plasma Core Electron Density and Temperature Measurements Using CVI Line Emissions in TCABR Tokamak

    NASA Astrophysics Data System (ADS)

    do Nascimento, F.; Machida, M.; Severo, J. H. F.; Sanada, E.; Ronchi, G.

    2015-08-01

    In this work, we present results of electron temperature ( T e ) and density ( n e ) measurements obtained in Tokamak Chauffage Alfvén Brésilien (TCABR) tokamak using visible spectroscopy from CVI line emissions which occurs mainly near the center of the plasma column. The presented method is based on a well-known relationship between the particle flux ( Γ ion) and the photon flux ( ø ion) emitted by an ion species combined with ionizations per photon atomic data provided by the atomic data and analysis structure (ADAS) database. In the experiment, we measured the photon fluxes of three different CVI spectral line emissions, 4685.2, 5290.5, and 6200.6 Å (one line per shot). Using this method it was possible to find out the temporal evolution of T e and n e in the plasma. The results achieved are in good agreement with T e and n e measurements made using other diagnostic tools.

  12. Ion-acoustic Gardner Solitons in electron-positron-ion plasma with two-electron temperature distributions

    NASA Astrophysics Data System (ADS)

    Rehman, Momin A.; Mishra, M. K.

    2016-01-01

    The ion-acoustic solitons in collisionless plasma consisting of warm adiabatic ions, isothermal positrons, and two temperature distribution of electrons have been studied. Using reductive perturbation method, Korteweg-de Vries (K-dV), the modified K-dV (m-KdV), and Gardner equations are derived for the system. The soliton solution of the Gardner equation is discussed in detail. It is found that for a given set of parameter values, there exists a critical value of β=Tc/Th, (ratio of cold to hot electron temperature) below which only rarefactive KdV solitons exist and above it compressive KdV solitons exist. At the critical value of β, both compressive and rarefactive m-KdV solitons co-exist. We have also investigated the soliton in the parametric regime where the KdV equation is not valid to study soliton solution. In this region, it is found that below the critical concentration the system supports rarefactive Gardner solitons and above it compressive Gardner solitons are found. The effects of temperature ratio of two-electron species, cold electron concentration, positron concentration on the characteristics of solitons are also discussed.

  13. Instability and dynamics of two nonlinearly coupled laser beams in a two-temperature electron plasma.

    PubMed

    Eliasson, B; Shukla, P K

    2006-10-01

    We consider nonlinear interactions between two colliding laser beams in an electron plasma, accounting for the relativistic electron mass increase in the laser fields and radiation pressure driven electron-acoustic (EA) perturbations that are supported by hot and cold electrons. By using the hydrodynamic and Maxwell equations, we obtain the relevant equations for nonlinearly coupled laser beams and EA perturbations. The coupled equations are then Fourier analyzed to obtain a nonlinear dispersion relation. The latter is numerically solved to show the existence of new classes of the parametric instabilities in the presence of two colliding laser beams in a two-electron plasma. The dynamics of nonlinearly coupled laser beams in our electron plasma is also investigated. The results should be useful in understanding the nonlinear propagation characteristics of multiple electromagnetic beams in laser-produced plasmas as well as in space plasmas.

  14. Remarkable Rise in Electron-Ion Recombination of O II for Low Temperature Nebular Plasmas

    NASA Astrophysics Data System (ADS)

    Nahar, Sultana; Pradhan, Anil

    2011-05-01

    Recombination is dominant in cooler nebular plasmas and recombination lines (RCL) of O II are commonly detected. Collisionally excited lines (CEL) are also common. But a longstanding discrepancy of lower and higher oxygen abundance exists predicted from the RCL and CEL respectively. This is a puzzle since existent atomic parameters for O II are known to be accurate. We have studied the low energy photoionization and low temperature recombination of O II using the unified method based on relativistic Breit-Pauli R-matrix method and close coupling approximation. We find that the fine structure effects in the low temperature region, studied for the first time, cause considerable enhancement in electron-ion recombination rates. The enhancement comes from the intense narrow resonances, allowed in fine structure but not in LS coupling approximation, in a small energy region right at the ionization threshold. Due to the small energy range that contains these resonances, experiment was unable to detect them. We will present detailed features and recombination rates at low temperature which are expected to narrow the gap of discrepancy in oxygem abundance in nebular plasmas. Partial supports: NSF, DOE

  15. Research on soft x-rays in high-current plasma-focus discharges and estimation of plasma electron temperature

    NASA Astrophysics Data System (ADS)

    Skladnik-Sadowska, E.; Zaloga, D.; Sadowski, M. J.; Kwiatkowski, R.; Malinowski, K.; Miklaszewski, R.; Paduch, M.; Surala, W.; Zielinska, E.; Tomaszewski, K.

    2016-09-01

    The paper presents results of experimental studies of dense and high-temperature plasmas, which were produced by pulsed high-current discharges within a modernised PF-1000U facility operated at different initial gas conditions, and supplied from a condenser bank which delivered energy of about 350 kJ. The investigated discharges were performed at the initial deuterium filling under pressure of 1.6-2.0 hPa, with or without an additional puffing of pure deuterium (1 cm3, under pressure 0.15 MPa, at instants 1.5-2 ms before the main discharge initiation). For a comparison discharges were also performed at the initial neon filling under pressure of 1.1-1.3 hPa, with or without the addition of deuterium puffing. The recorded discharge current waveforms, laser interferometric images, signals of hard x-rays and fusion neutrons, as well as time-integrated x-ray pinhole images and time-resolved x-ray signals were compared. From a ratio of the x-ray signals recorded behind beryllium filters of different thickness there were estimated values of a plasma electron temperature (T e) in a region at the electrode outlets. For pure deuterium discharges an averaged T e value amounted to 150-170 eV, while for neon discharges with the deuterium puffing it reached 330-880 eV (with accuracy of  ±20%).

  16. Origin of low proton-to-electron temperature ratio in the Earth's plasma sheet

    NASA Astrophysics Data System (ADS)

    Grigorenko, E. E.; Kronberg, E. A.; Daly, P. W.; Ganushkina, N. Yu.; Lavraud, B.; Sauvaud, J.-A.; Zelenyi, L. M.

    2016-10-01

    We study the proton-to-electron temperature ratio (Tp/Te) in the plasma sheet (PS) of the Earth's magnetotail using 5 years of Cluster observations (2001-2005). The PS intervals are searched within a region defined with -19 < X ≤ -7 RE and |Y| < 15 RE (GSM) under the condition |BX| ≤ 10 nT. One hundred sixty PS crossings are identified. We find an average value of 6.0. However, in many PS intervals Tp/Te varies over a wide range from a few units to several tens of units. In 86 PS intervals the Tp/Te decreases below 3.5. Generally, the decreases of Tp/Te are due to some increase of Te while Tp either decreases or remains unchanged. In the majority of these intervals the Tp/Te drops are observed during magnetotail dipolarizations. A superposed epoch analysis applied to these events shows that the minimum value of Tp/Te is observed after the dipolarization onset during the "turbulent phase" of dipolarization, when a number of transient BZ pulses are reduced, but the value of BZ is still large and an intensification of wave activity is observed. The Tp/Te drops, and associated increases of Te often coincide either with bursts of broadband electrostatic emissions, which may include electron cyclotron harmonics, or with broadband electromagnetic emission in a frequency range from proton plasma frequency (fpp) up to the electron gyrofrequency (fce). These findings show that the wave activity developing in the current sheet after dipolarization onset may play a role in the additional electron heating and the associated Tp/Te decrease.

  17. Time-resolved ion flux, electron temperature and plasma density measurements in a pulsed Ar plasma using a capacitively coupled planar probe

    NASA Astrophysics Data System (ADS)

    Darnon, Maxime; Cunge, Gilles; Braithwaite, Nicholas St. J.

    2014-04-01

    The resurgence of industrial interest in pulsed radiofrequency plasmas for etching applications highlights the fact that these plasmas are much less well characterized than their continuous wave counterparts. A capacitively coupled planar probe is used to determine the time variations of the ion flux, electron temperature (of the high-energy tail of the electron energy distribution function) and plasma density. For a pulsing frequency of 1 kHz or higher, the plasma never reaches a steady state during the on-time and is not fully extinguished during the off-time. The drop of plasma density during the off-time leads to an overshoot in the electron temperature at the beginning of each pulse, particularly at low frequencies, in good agreement with modeling results from the literature.

  18. Transitional properties of supersolitons in a two electron temperature warm multi-ion plasma

    SciTech Connect

    Varghese, Steffy S. Ghosh, S. S.

    2016-08-15

    The existence domain of an ion acoustic supersoliton and its transition to a regular kind of solitary wave have been explored in detail using Sagdeev pseudopotential technique for a two electron temperature warm multi-ion plasma having two species of ions. It was found that both the cold to hot electron temperature ratio and their respective ambient densities play a deterministic role for the existence of a supersoliton, as well as its transitional processes to a regular solitary wave. Analogous to a double layer solution, which often marks the boundary of the existence domain of a regular solitary wave, a “curve of inflection” determines the boundary of the existence domain of a supersoliton. The characteristics of the “curve of inflection,” in turn, depend on the respective concentrations of the two ion species. It is observed that the supersolitons are actually a subset of a more general kind of solutions which are characterized by a fluctuation in the corresponding charge separation which precedes their maximum amplitude. It is also observed that these novel kinds of solitary structures, including supersolitons, occur only for a very narrow range of parameters near constant amplitude beyond which the wave breaks.

  19. Modified Korteweg-de Vries solitons at supercritical densities in two-electron temperature plasmas

    NASA Astrophysics Data System (ADS)

    Verheest, Frank; Olivier, Carel P.; Hereman, Willy A.

    2016-04-01

    > The supercritical composition of a plasma model with cold positive ions in the presence of a two-temperature electron population is investigated, initially by a reductive perturbation approach, under the combined requirements that there be neither quadratic nor cubic nonlinearities in the evolution equation. This leads to a unique choice for the set of compositional parameters and a modified Korteweg-de Vries equation (mKdV) with a quartic nonlinear term. The conclusions about its one-soliton solution and integrability will also be valid for more complicated plasma compositions. Only three polynomial conservation laws can be obtained. The mKdV equation with quartic nonlinearity is not completely integrable, thus precluding the existence of multi-soliton solutions. Next, the full Sagdeev pseudopotential method has been applied and this allows for a detailed comparison with the reductive perturbation results. This comparison shows that the mKdV solitons have slightly larger amplitudes and widths than those obtained from the more complete Sagdeev solution and that only slightly superacoustic mKdV solitons have acceptable amplitudes and widths, in the light of the full solutions.

  20. Simultaneous measurement of electron and heavy particle temperatures in He laser-induced plasma by Thomson and Rayleigh scattering

    SciTech Connect

    Dzierzega, K.; Mendys, A.; Zawadzki, W.; Pokrzywka, B.; Pellerin, S.

    2013-04-01

    Thomson and Rayleigh scattering methods were applied to quantify the electron and heavy particle temperatures, as well as electron number density, in a laser spark in helium at atmospheric pressure. Plasma was created using 4.5 ns, 25 mJ pulses from Nd:YAG laser at 532 nm. Measurements, performed for the time interval between 20 ns and 800 ns after breakdown, show electron density and temperature to decrease from 7.8 Multiplication-Sign 10{sup 23} m{sup -3} to 2.6 Multiplication-Sign 10{sup 22} m{sup -3} and from 95 900 K to 10 350 K, respectively. At the same time, the heavy particle temperature drops from only 47 000 K down to 4100 K which indicates a two temperature plasma out of local isothermal equilibrium.

  1. Formation of Nanoparticles by Control of Electron Temperature in Hollow-Typed Magnetron Radio Frequency CH4/H2 Plasma

    NASA Astrophysics Data System (ADS)

    Emi, Junichi; Kato, Kohgi; Abe, Toshimi; Iizuka, Satoru

    2006-10-01

    In this study, we investigate the effects of electron temperature Te on the production of nanoparticles by using the grid-biasing method in hollow-typed magnetron radio frequency (RF) CH4/H2 plasma. We find that nanoparticles are produced in low-Te plasma. On the other hand, thin film depositions, such as nanowalls, are mainly observed and almost no nanoparticles are created in high-Te plasma. This implies that a reduction in the CH2/CH3 radical ratio is important for producing nanoparticles, together with a reduction in sheath potential in front of the substrate. The change in electron temperature in plasma has a marked effect on film quality.

  2. The effect of sample matrix on electron density, electron temperature and gas temperature in the argon inductively coupled plasma examined by Thomson and Rayleigh scattering

    NASA Astrophysics Data System (ADS)

    Hanselman, D. S.; Sesi, N. N.; Huang, M.; Hieftje, G. M.

    1994-05-01

    Spatially-resolved electron temperature ( Te), electron number density ( ne) and gas-kinetic temperature ( Tg) maps of the inductively coupled plasma (ICP) have been obtained for two central-gas flow rates, four heights above the load coil (ALC) and in the presence and absence of interferants with a wide range of first ionization potentials. The radial profiles demonstrate how the directly measured fundamental parameters neTe and Tg can be significantly enhanced and/or depressed with added interferent, depending upon plasma operating conditions and observation region. In general, the magnitude of ne, and Te change is found to be an inverse function of interferent ionization potential; furthermore, ne enhancements in the central channel might be the result of electron redistribution from high to low electron density regions rather than from ionization of the matrix. The large measured increases in ne cannot be attributed solely to matrix ionization, especially when measurement uncertainties and the probable over-estimation in calculated ne, enhancements are taken into account. Changes in ne and Te have been correlated with axial Ca atom and ion emission profiles. A brief review of the mechanisms most likely involved in interelement matrix interferences is given within the context of the present study. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by a disk for the Macintosh computer with data files stored in ASCII format. The main article discusses the scientific aspects of the subject and gives an interpretation of the results contained in the data files.

  3. Electron temperature and density of non-thermal atmospheric pressure argon plasma jet by convective wave packet model

    NASA Astrophysics Data System (ADS)

    Sornsakdanuphap, Jirapong; Suanpoot, Pradoong; Hong, Young June; Ghimire, Bhagirath; Cho, Guangsup; Uhm, Han Sup; Kim, Doyoung; Kim, Yun Ji; Choi, Eun Ha

    2017-06-01

    The propagation velocities ( u g ) of argon plasma jet are obtained by intensified charge coupled device (ICCD) camera images at fixed gate width time of 5 ns. The propagation velocities in upstream and downstream regions are in the order of 104 - 105 m/s. The plasma ambipolar diffusion velocities are measured to be in the order of 10 - 102 m/s. Plasma jet discharges are generated by sinusoidal power supply in varying voltages from 2 to 4 kV at repetition frequency of about 40 kHz. By employing convective wave packet model, the electron temperature ( T e ) inside plasma bullet for argon non-thermal atmospheric pressure plasma jet is estimated to be about 1.18 eV. Also, the electron density ( n e ) is found to be 8.0 × 1014 - 2.5 × 1015 cm-3.

  4. Boundary conditions at the walls with thermionic electron emission in two temperature modeling of “thermal” plasmas

    SciTech Connect

    Pekker, Leonid; Hussary, Nakhleh

    2015-08-15

    In this paper, we propose new boundary conditions for the electric potential, the electron energy equation, and the energy equation for heavy particles (ions and neutrals) at the hot walls with thermionic electron emission for two-temperature thermal arc models. The derived boundary conditions assume that the walls are made from refractory metals and, consequently, the erosion of the wall is small and can be neglected. In these boundary conditions, the plasma sheath formed at the electrode is viewed as the interface between the plasma and the wall. The derived boundary conditions allow the calculation of the heat flux to the walls from the plasma. This allows the calculation of the thermionic electron current that makes the model of electrode-plasma interaction self-consistent.

  5. Spectroscopic and probe measurements of the electron temperature in the plasma of a pulse-periodic microwave discharge in argon

    SciTech Connect

    Andreev, V. V. Vasileska, I. Korneeva, M. A.

    2016-07-15

    A pulse-periodic 2.45-GHz electron-cyclotron resonance plasma source on the basis of a permanent- magnet mirror trap has been constructed and tested. Variations in the discharge parameters and the electron temperature of argon plasma have been investigated in the argon pressure range of 1 × 10{sup –4} to 4 × 10{sup –3} Torr at a net pulsed input microwave power of up to 600 W. The plasma electron temperature in the above ranges of gas pressures and input powers has been measured by a Langmuir probe and determined using optical emission spectroscopy (OES) from the intensity ratios of spectral lines. The OES results agree qualitatively and quantitatively with the data obtained using the double probe.

  6. Effects of rf power on electron density and temperature, neutral temperature, and T{sub e} fluctuations in an inductively coupled plasma

    SciTech Connect

    Camparo, James; Fathi, Gilda

    2009-05-15

    Atomic clocks that fly on global-navigation satellites such as global positioning system (GPS) and Galileo employ light from low-temperature, inductively coupled plasmas (ICPs) for atomic signal generation and detection (i.e., alkali/noble-gas rf-discharge lamps). In this application, the performance of the atomic clock and the capabilities of the navigation system depend sensitively on the stability of the ICP's optical emission. In order to better understand the mechanisms that might lead to instability in these rf-discharge lamps, and hence the satellite atomic clocks, we studied the optical emission from a Rb/Xe ICP as a function of the rf power driving the plasma. Surprisingly, we found that the electron density in the plasma was essentially independent of increases in rf power above its nominal value (i.e., 'rf-power gain') and that the electron temperature was only a slowly varying function of rf-power gain. The primary effect of rf power was to increase the temperature of the neutrals in the plasma, which was manifested by an increase in Rb vapor density. Interestingly, we also found evidence for electron temperature fluctuations (i.e., fluctuations in the plasma's high-energy electron content). The variance of these fluctuations scaled inversely with the plasma's mean electron temperature and was consistent with a simple model that assumed that the total electron density in the discharge was independent of rf power. Taken as a whole, our results indicate that the electrons in alkali/noble-gas ICPs are little affected by slight changes in rf power and that the primary effect of such changes is to heat the plasma's neutral species.

  7. Quasilinear dynamics of a cloud of hot electrons propagating through a plasma with decreasing density and temperature

    NASA Astrophysics Data System (ADS)

    Foroutan, G.; Khalilpour, H.; Moslehi-Fard, M.; Li, B.; Robinson, P. A.

    2008-12-01

    The effects of plasma inhomogeneities on the propagation of a cloud of hot electrons through a cold background plasma and generation of Langmuir waves are investigated using numerical simulations of the quasilinear equations. It is found that in a plasma with decreasing density the quasilinear relaxation of the electron distribution in velocity space is accelerated and the levels of the generated Langmuir waves are enhanced. The magnitude of the induced emission rate is increased and its maximum value moves to lower velocities. Due to density gradient the height of plateau shows an increase at small distances and a corresponding decrease at large distances. It is also found that in a plasma with decreasing temperature, the relaxation of the beam is retarded, the spectral density of Langmuir waves is broadened, and the height of the plateau decreases below its value in a uniform plasma. In the presence of both density and temperature gradients, at given position, the height and upper boundary of the plateau and the level of Langmuir waves are all increased at small velocities. The spatial expansion of the beam is increased by the plasma inhomogeneities, but its average velocity of propagation decreases. Initially, at a given position, the velocity at the upper boundary of the plateau is smaller in the presence of the density gradient than in the uniform plasma but the reverse is true at longer times. Due to temperature gradient, at large times and small distances, the upper boundary of the plateau is increased above its value in the uniform plasma. Because of fast relaxation, the value of the lower boundary of the plateau in the plasma with decreasing density is always less than its value in the uniform plasma. It is found that the local velocity of the beam decreases when the density gradient is present. The local velocity spread of the beam remains unchanged during the propagation of the beam in the uniform plasma, but increases in the presence of inhomogeneities.

  8. Quasilinear dynamics of a cloud of hot electrons propagating through a plasma with decreasing density and temperature

    SciTech Connect

    Foroutan, G.; Khalilpour, H.; Moslehi-Fard, M.; Li, B.; Robinson, P. A.

    2008-12-15

    The effects of plasma inhomogeneities on the propagation of a cloud of hot electrons through a cold background plasma and generation of Langmuir waves are investigated using numerical simulations of the quasilinear equations. It is found that in a plasma with decreasing density the quasilinear relaxation of the electron distribution in velocity space is accelerated and the levels of the generated Langmuir waves are enhanced. The magnitude of the induced emission rate is increased and its maximum value moves to lower velocities. Due to density gradient the height of plateau shows an increase at small distances and a corresponding decrease at large distances. It is also found that in a plasma with decreasing temperature, the relaxation of the beam is retarded, the spectral density of Langmuir waves is broadened, and the height of the plateau decreases below its value in a uniform plasma. In the presence of both density and temperature gradients, at given position, the height and upper boundary of the plateau and the level of Langmuir waves are all increased at small velocities. The spatial expansion of the beam is increased by the plasma inhomogeneities, but its average velocity of propagation decreases. Initially, at a given position, the velocity at the upper boundary of the plateau is smaller in the presence of the density gradient than in the uniform plasma but the reverse is true at longer times. Due to temperature gradient, at large times and small distances, the upper boundary of the plateau is increased above its value in the uniform plasma. Because of fast relaxation, the value of the lower boundary of the plateau in the plasma with decreasing density is always less than its value in the uniform plasma. It is found that the local velocity of the beam decreases when the density gradient is present. The local velocity spread of the beam remains unchanged during the propagation of the beam in the uniform plasma, but increases in the presence of inhomogeneities.

  9. Statistical Physics of Electron Temperature of Low-Pressure Discharge Nitrogen Plasma with Non-Maxwellian EEDF

    NASA Astrophysics Data System (ADS)

    Akatsuka, Hiroshi; Tanaka, Yoshinori

    2016-09-01

    We reconsider electron temperature of non-equilibrium plasmas on the basis of thermodynamics and statistical physics. Following our previous study on the oxygen plasma in GEC 2015, we discuss the common issue for the nitrogen plasma. First, we solve the Boltzmann equation to obtain the electron energy distribution function (EEDF) F(ɛ) of the nitrogen plasma as a function of the reduced electric field E / N . We also simultaneously solve the chemical kinetic equations of some essential excite species of nitrogen molecules and atoms, including vibrational distribution function (VDF). Next, we calculate the electron mean energy as U = < ɛ > =∫0∞ɛF(ɛ) dɛ and entropy S = - k∫0∞F(ɛ) ln [ F(ɛ) ] dɛ for each value of E / N . Then, we can obtain the electron temperature as Testat =[ ∂S / ∂U ] - 1 . After that, we discuss the difference between Testat and the kinetic temperature Tekin ≡(2 / 3) < ɛ > , as well as the temperature given as a slope of the calculated EEDF for each value of E / N . We found Testat is close to the slope at ɛ 4 eV in the EEPF.

  10. Weibel instability for a streaming electron, counterstreaming e-e, and e-p plasmas with intrinsic temperature anisotropy

    SciTech Connect

    Ghorbanalilu, M.; Sadegzadeh, S.; Ghaderi, Z.; Niknam, A. R.

    2014-05-15

    The existence of Weibel instability for a streaming electron, counterstreaming electron-electron (e-e), and electron-positron (e-p) plasmas with intrinsic temperature anisotropy is investigated. The temperature anisotropy is included in the directions perpendicular and parallel to the streaming direction. It is shown that the beam mean speed changes the instability mode, for a streaming electron beam, from the classic Weibel to the Weibel-like mode. The analytical and numerical solutions approved that Weibel-like modes are excited for both counterstreaming e-e and e-p plasmas. The growth rates of the instabilities in e-e and e-p plasmas are compared. The growth rate is larger for e-p plasmas if the thermal anisotropy is small and the opposite is true for large thermal anisotropies. The analytical and numerical solutions are in good agreement only in the small parallel temperature and wave number limits, when the instability growth rate increases linearly with normalized wave number kc∕ω{sub p}.

  11. Finite amplitude nonlinear drift waves in a spatially inhomogeneous degenerate plasma with Landau quantization and electron temperature corrections

    NASA Astrophysics Data System (ADS)

    Shaukat, Muzzamal I.; Masood, W.; Shah, H. A.; Iqbal, M. J.; Mirza, Arshad M.

    2016-10-01

    In the present investigation, linear and nonlinear electrostatic drift waves in the presence of trapped electrons with quantizing magnetic field and finite electron temperature effects in dense plasmas have been studied. The linear dispersion relation of the ion drift wave has been derived and it has been found that the Landau quantization and finite temperature effects significantly alter the linear propagation characteristics of the wave under consideration. Employing the Sagdeev potential approach, the formation of finite amplitude drift solitary structures has been investigated in the presence of a quantizing magnetic field for both fully and partially degenerate plasmas. Both compressive and rarefactive drift solitary structures have been obtained for different values of quantizing magnetic field and finite electron temperature effects. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs.

  12. Two-dimensional quasi-double-layers in two-electron-temperature, current-free plasmas

    SciTech Connect

    Merino, Mario; Ahedo, Eduardo

    2013-02-15

    The expansion of a plasma with two disparate electron populations into vacuum and channeled by a divergent magnetic nozzle is analyzed with an axisymmetric model. The purpose is to study the formation and two-dimensional shape of a current-free double-layer in the case when the electric potential steepening can still be treated within the quasineutral approximation. The properties of this quasi-double-layer are investigated in terms of the relative fraction of the high-energy electron population, its radial distribution when injected into the nozzle, and the geometry and intensity of the applied magnetic field. The two-dimensional double layer presents a curved shape, which is dependent on the natural curvature of the equipotential lines in a magnetically expanded plasma and the particular radial distribution of high-energy electrons at injection. The double layer curvature increases the higher the nozzle divergence is, the lower the magnetic strength is, and the more peripherally hot electrons are injected. A central application of the study is the operation of a helicon plasma thruster in space. To this respect, it is shown that the curvature of the double layer does not increment the thrust, it does not modify appreciably the downstream divergence of the plasma beam, but it increases the magnetic-to-pressure thrust ratio. The present study does not attempt to cover current-free double layers involving plasmas with multiple populations of positive ions.

  13. Spectroscopic diagnostics of electron temperature and energy conversion efficiency of laser-sustained plasma in flowing argon

    NASA Astrophysics Data System (ADS)

    Mazumder, J.; Krier, H.; Chen, X.

    1988-08-01

    Laser sustained plasmas are often formed during laser materials interaction. The University's 10 kW CW CO2 laser has been used to study argon plasmas for the application to laser supported propulsion and laser materials processing. The spectroscopic diagnostic method has been applied to study laser-sustained plasmas in 1 atmosphere pure argon gas flow with an f/7 on-axis laser focusing scheme. High flow speeds of 2 to 10 m/sec are achieved. Plasma electron temperatures distributions are determined from the 415.8 nm Ar1 line and its adjacent continuum intensities. Plasma core temperatures as high as 20,000 K are reported. The total absorption of the incident laser power and the radiation loss by the plasma are calculated from the temperature distribution. Results indicated that up to 86 percent of the incident laser power can be absorbed and nearly 60 percent of the incident laser power can be retained by the flowing argon gas to provide thrust. Further research is called for in the Laser Induced Fluorescence (LIF) technique for diagnostics of the downstream mixing zone and the plasma outer region. Experiments over a wider range of operating conditions, as well as multiple plasma testings, are required to find the optimum operating scheme.

  14. Ion-acoustic solitons and double layers in a two-electron temperature plasma with hot isothermal electrons and cold ions

    NASA Astrophysics Data System (ADS)

    Tagare, S. G.

    2000-03-01

    It is found that a two-electron temperature plasma with isothermal electrons and cold ions admits both compressive and rarefactive solitons, as well as compressive and rarefactive double layers (depending on the concentration of low-temperature electrons). In this paper, a Korteweg-de Vries (K-dV) equation and a K-dV-type equation with cubic and fourth-order nonlinearity at the critical density of the low-temperature isothermal electrons are derived to discuss the properties of ion-acoustic solitons in a two-electron temperature plasma. In the vicinity of the critical electron density of low-temperature isothermal electrons, we have derived a K-dV-type equation with mixed nonlinearity, and the solution of this equation will have both compressive and rarefactive double layers for those values of critical electron density of low-temperature electrons for which ion-acoustic solitons do not exist. By using quasipotential analysis, critical Mach numbers M1c and M2c are obtained such that compressive ion-acoustic solitons exist when 1

  15. Plasma spectroscopic diagnostic tool using collisional-radiative models and its application to different plasma discharges for electron temperature and neutral density determination

    NASA Astrophysics Data System (ADS)

    Sciamma, Ella Marion

    A spectroscopic diagnostic tool has been developed to determine the electron temperature and the neutral density in helium, hydrogen and argon plasmas from absolutely calibrated spectroscopic measurements. For each gas, a method of analysis which uses models specific to each species present in the plasma (neutral atom or singly ionized atom) has been defined. The experimental electron density is used as an input parameter to the models, and the absolutely calibrated spectroscopic data are processed beforehand to obtain the populations of the upper excited levels corresponding to the observed spectral lines. For helium plasmas, the electron temperature is inferred from the experimental helium ion excited level p = 4 population using a corona model, and then the neutral density is determined from the experimental helium neutral excited level populations using a collisional-radiative model for helium neutrals. For hydrogen plasmas, combinations of the electron temperature and the neutral density are determined from the experimental hydrogen neutral excited level populations using a collisional-radiative model specific to hydrogen atoms. For argon plasmas, the electron temperature is inferred from the experimental argon ion excited level populations using a collisional-radiative model for argon ions, and then the neutral density is determined from the experimental argon neutral excited level populations using a collisional-radiative model for argon neutrals. This diagnostic tool was applied to three experiments with different geometries and plasma conditions to test the validity of each data analysis method. The helium and hydrogen data analysis methods were tested and validated on helium and hydrogen plasmas produced in the VASIMR experiment, a plasma propulsion system concept. They gave electron temperatures and neutral densities that were consistent with other diagnostics and theory. The argon diagnostic tool was tested on argon plasmas produced in the VASIMR

  16. Electron Temperature and Density Variation Due To Temporal Evolution of Nano Particle Growth in RF Silane Plasma

    SciTech Connect

    Chai, K. B.; Seon, C. R.; Choe, W.; Park, S.; Chung, C. W.

    2008-09-07

    Nano particles, generated in various processing plasmas, have been extensively studied for applications in the fabrication of microelectronics devices. However, studies to find the relation between the particle parameters (particle size and density) and the plasma parameters (electron temperature and density) have been limited because of the availability of the appropriate diagnostic method. The utilization of Langmuir probes are limited in many cases due to the probe tip contamination and the presence of abundant negative ions and particles. In this work, measurements of electron temperature and ion density were performed in rf silane plasmas using a floating probe, which allows an accurate measurement even under harsh plasma environments. The size and density of nano particles were measured by the laser light scattering and the laser extinction method at various gas pressures. It was found that the temporal evolution of the particle growth played a significant role in changing the plasma parameters due to the electron and ion fluxes to the particles. The relation between the plasma parameters and the particle parameters was described by a power balance equation including the power loss to the particle surface.

  17. Electronic excitation and isentropic coefficients of high temperature planetary atmosphere plasmas

    SciTech Connect

    Colonna, Gianpiero; Capitelli, Mario

    2012-07-15

    In this paper, we have discussed the effects of electronically excited states of atomic species in affecting the isentropic coefficients of plasmas, focusing on mixtures representing the atmospheres of Jupiter, Mars, and Earth. General behaviors have been rationalized on the basis of simplified approaches. The contribution of the electronically excited states has been evidenced by comparing results obtained considering only the ground state and those obtained using either Fermi or Griem cutoff criteria.

  18. Determination of plasma temperature and electron density of iron in iron slag samples using laser induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Hussain, T.; Gondal, M. A.; Shamraiz, M.

    2016-08-01

    Plasma temperature and electron density of iron in iron slag samples taken from a local plant is studied. Optimal experimental conditions were evaluated using Nd: YAG laser at 1064 nm. Some toxic elements were identified and quantitative measurements were also made. Plasma temperature and electron density were estimated using standard equations and well resolved iron spectral lines in the 229.06-358.11 nm region at 10, 20, 30 and 40 mJ laser pulse energy with 4.5 μs delay time. These parameters were found to increase with increase in laser pulse energy. The Boltzmann distribution and experimentally measured line intensities support the assumption that the laser-induced plasma was in local thermal equilibrium. It is worth mentioning that iron and steel sector generates tons of solid waste and residues annually containing variety of contaminants which can be harmful to the environment and therefore knowledge, proper analysis and investigation of such iron slag is important.

  19. Comparison of plasma temperature and electron density on nanosecond laser ablation of Cu and nano-Cu

    SciTech Connect

    Chen, Anmin; Jiang, Yuanfei; Wang, Tingfeng; Shao, Junfeng; Jin, Mingxing

    2015-03-15

    Laser-induced breakdown spectroscopy is performed through the collection of spectra by spectral detection equipment at different delay times and distances from targets composed of Cu and nano-Cu, which are ablated using a Nd:YAG laser (532 nm, 10 ns, 10 Hz) in our experiments. The measured wavelength range is from 475 nm to 525 nm. Using the local thermodynamic equilibrium model, we analyze the characteristics of the plasma temperature and the electron number density for different distances between the target surface and the lens. The results show that when compared with the nano-Cu plasma case, the temperature of the Cu plasma is higher, while its electron number density is lower.

  20. METHES: A Monte Carlo collision code for the simulation of electron transport in low temperature plasmas

    NASA Astrophysics Data System (ADS)

    Rabie, M.; Franck, C. M.

    2016-06-01

    We present a freely available MATLAB code for the simulation of electron transport in arbitrary gas mixtures in the presence of uniform electric fields. For steady-state electron transport, the program provides the transport coefficients, reaction rates and the electron energy distribution function. The program uses established Monte Carlo techniques and is compatible with the electron scattering cross section files from the open-access Plasma Data Exchange Project LXCat. The code is written in object-oriented design, allowing the tracing and visualization of the spatiotemporal evolution of electron swarms and the temporal development of the mean energy and the electron number due to attachment and/or ionization processes. We benchmark our code with well-known model gases as well as the real gases argon, N2, O2, CF4, SF6 and mixtures of N2 and O2.

  1. Electronic ground state OH(X) radical in a low-temperature atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Fuh, Che A.; Clark, Shane M.; Wu, Wei; Wang, Chuji

    2016-10-01

    The wide applicability of atmospheric pressure plasma jets in biomedicine stems from the presence of reactive nitrogen and oxygen species generated in these plasma jets. Knowing the absolute concentration of these reactive species is of utmost importance as it is critical, along with the particle flux obtained from the plasma feed gas flow rate to ensure that the correct dosage is applied during applications. In this study, we investigate and report the ground state OH(X) number density acquired using cavity ringdown spectroscopy, along the propagation axis (z-axis) of a cold atmospheric pressure helium plasma plume. The jet was generated by a repetitively pulsed mono-polar square wave of duration 1 μs running at a frequency of 9.9 kHz. The voltage supplied was 6.5 kV with the helium flow rate fixed at 3.6 standard liters per minute. The rotational and vibrational temperatures are simulated from the second positive system of nitrogen, N 2(C3πu-B3πg) , with the rotational temperature being spatially constant at 300 K along the propagation axis of the atmospheric pressure plasma jet while the vibrational temperature is 3620 K at the beginning of the plume and is observed to decrease downstream. The OH(A) emission intensity obtained via optical emission spectroscopy was observed to decrease downstream of the plasma jet. The OH(X) number density along the propagation axis was initially 2.2 × 1013 molecules cm-3 before increasing to a peak value of 2.4 × 1013 molecules cm-3, from which the number density was observed to decrease to 2.2 × 1013 molecules cm-3 downstream of the plasma jet. The total OH(A, X) in the plasma jet remained relatively constant along the propagation axis of the plasma jet before falling off at the tip of the jet. The increase in vibrational temperature downstream and the simultaneous measurements of both the excited state OH(A) and the ground state OH(X) reported in this study provide insights into the formation and consumption of this

  2. New Electron Temperature Measurements During Local Helicity Injection and H-mode Plasmas at the Pegasus Toroidal Experiment

    NASA Astrophysics Data System (ADS)

    Schlossberg, D. J.; Bodner, G. M.; Fonck, R. J.; Reusch, J. A.; Winz, G. R.

    2015-11-01

    Extrapolation of non-solenoidal startup via local helicity injection (LHI) to larger devices depends critically on confinement during the injection process. To begin quantifying confinement regimes, the Thomson scattering diagnostic on the Pegasus ST was upgraded to include 12 radial positions and high temperature (0.1 electron distributions, with central Te = 150 eV. In the low-density LHI startup plasmas shot-to-shot averaging of data improves background measurements and increases signal-to-noise ratio. Initial core measurements during the drive phase of LHI suggest average Te of several hundred eV for plasmas with ne ~ 3x1018 m-3 and Ip ~ 0.15 MA. Experiments are underway to verify these unexpectedly high electron temperatures. If verified, these temperatures may reflect the dominance of high-energy electrons via fueling with LHI current streams with average energy ~1 keV. Further investigations will explore the dependence of the inferred electron distribution on fueling source, density, and electron injection potential. The upgraded Thomson scattering diagnostic will also be applied to Ohmic H-mode plasmas in Pegasus. Work supported by US DOE grant DE-FG02-96ER54375.

  3. Consistent multi-internal-temperature models for vibrational and electronic nonequilibrium in hypersonic nitrogen plasma flows

    SciTech Connect

    Guy, Aurélien Bourdon, Anne Perrin, Marie-Yvonne

    2015-04-15

    In this work, a state-to-state vibrational and electronic collisional model is developed to investigate nonequilibrium phenomena behind a shock wave in an ionized nitrogen flow. In the ionization dynamics behind the shock wave, the electron energy budget is of key importance and it is found that the main depletion term corresponds to the electronic excitation of N atoms, and conversely the major creation terms are the electron-vibration term at the beginning, then replaced by the electron ions elastic exchange term. Based on these results, a macroscopic multi-internal-temperature model for the vibration of N{sub 2} and the electronic levels of N atoms is derived with several groups of vibrational levels of N{sub 2} and electronic levels of N with their own internal temperatures to model the shape of the vibrational distribution of N{sub 2} and of the electronic excitation of N, respectively. In this model, energy and chemistry source terms are calculated self-consistently from the rate coefficients of the state-to-state database. For the shock wave condition studied, a good agreement is observed on the ionization dynamics as well as on the atomic bound-bound radiation between the state-to-state model and the macroscopic multi-internal temperature model with only one group of vibrational levels of N{sub 2} and two groups of electronic levels of N.

  4. Ion acoustic solitary waves and double layers in a plasma with two temperature electrons featuring Tsallis distribution

    SciTech Connect

    Shalini, Saini, N. S.

    2014-10-15

    The propagation properties of large amplitude ion acoustic solitary waves (IASWs) are studied in a plasma containing cold fluid ions and multi-temperature electrons (cool and hot electrons) with nonextensive distribution. Employing Sagdeev pseudopotential method, an energy balance equation has been derived and from the expression for Sagdeev potential function, ion acoustic solitary waves and double layers are investigated numerically. The Mach number (lower and upper limits) for the existence of solitary structures is determined. Positive as well as negative polarity solitary structures are observed. Further, conditions for the existence of ion acoustic double layers (IADLs) are also determined numerically in the form of the critical values of q{sub c}, f and the Mach number (M). It is observed that the nonextensivity of electrons (via q{sub c,h}), concentration of electrons (via f) and temperature ratio of cold to hot electrons (via β) significantly influence the characteristics of ion acoustic solitary waves as well as double layers.

  5. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in Z-pinch plasmas

    NASA Astrophysics Data System (ADS)

    Dutra, Eric; Presura, Radu; Covington, Aaron; Mancini, Roberto; Darling, Timothy; Angermeier, William

    2016-10-01

    Visible spectroscopic techniques are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. Experiments were conducted at the University of Nevada (Reno) at the Nevada Terawatt Facility (NTF) using the 1 MA Z-pinch (Zebra). The research explored the optical emission of Al III doublet, 4P 2P3/2 to 4S 2S1/2 and 4P 2P1/2 to 4s 2S1/2 transitions and used it to measure Zeeman, Stark, and Doppler broadened emission. The initial parameters for the line shape code are varied to simulate emission spectra. The simulated spectra are compared to experimental results. These results are used to infer temperature, electron density, and B-fields in the magnetized plasma.

  6. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas

    NASA Astrophysics Data System (ADS)

    Dutra, E. C.; Koch, J. A.; Presura, R.; Angermeier, W. A.; Darling, T.; Haque, S.; Mancini, R. C.; Covington, A. M.

    2016-11-01

    Spectroscopic techniques in the visible range are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening, and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. This manuscript presents the details of the experimental setup and line shape code, along with the results obtained from an Al iii doublet at the University of Nevada, Reno at Nevada Terawatt Facility. Future tests are planned to further evaluate the technique and modeling on other material wire array, gas puff, and DPF platforms.

  7. Effects of suprathermal electrons on the proton temperature anisotropy in space plasmas: Electromagnetic ion-cyclotron instability

    NASA Astrophysics Data System (ADS)

    Shaaban, S. M.; Lazar, M.; Poedts, S.; Elhanbaly, A.

    2016-06-01

    In collision-poor plasmas from space, e.g., the solar wind and planetary magnetospheres, the kinetic anisotropy of the plasma particles is expected to be regulated by the kinetic instabilities. Driven by an excess of ion (proton) temperature perpendicular to the magnetic field (T_{perp}>T_{allel}), the electromagnetic ion-cyclotron (EMIC) instability is fast enough to constrain the proton anisotropy, but the observations do not conform to the instability thresholds predicted by the standard theory for bi-Maxwellian models of the plasma particles. This paper presents an extended investigation of the EMIC instability in the presence of suprathermal electrons which are ubiquitous in these environments. The analysis is based on the kinetic (Vlasov-Maxwell) theory assuming that both species, protons and electrons, may be anisotropic, and the EMIC unstable solutions are derived numerically providing an accurate description for conditions typically encountered in space plasmas. The effects of suprathermal populations are triggered by the electron anisotropy and the temperature contrast between electrons and protons. For certain conditions the anisotropy thresholds exceed the limits of the proton anisotropy measured in the solar wind considerably restraining the unstable regimes of the EMIC modes.

  8. Isoelectronic x-ray spectroscopy to determine electron temperatures in long-scale-length inertial-confinement-fusion plasmas

    NASA Astrophysics Data System (ADS)

    Shepard, T. D.; Back, C. A.; Kalantar, D. H.; Kauffman, R. L.; Keane, C. J.; Klem, D. E.; Lasinski, B. F.; MacGowan, B. J.; Powers, L. V.; Suter, L. J.; Turner, R. E.; Failor, B. H.; Hsing, W. W.

    1996-05-01

    We have successfully employed isoelectronic line ratios to measure the electron temperature in gas-filled Hohlraum targets and gas bags shot with the Nova laser. These targets produce millimeter-scale-length plasmas with electron density Ne~1021 cm-3 and electron temperature Te~3 keV. The Hohlraum targets can also produce radiation temperature exceeding 200 eV. Isoelectronic line ratios are well suited to this measurement because they are relatively insensitive to radiation field effects in Hohlraum targets, opacity, transients, and variations in electron density compared to conventional line ratios. We survey the properties of isoelectronic line ratios formed from ratios of n-to-1 resonance transitions in heliumlike Cr to the same transitions in Ti and compare with conventional ratios of n-to-1 transitions in hydrogenlike Ti to the corresponding transitions in heliumlike Ti, concentrating on plasma parameter ranges of interest to the Nova experiments. We also consider the same ratios using K and Cl. Atomic kinetics are treated using collisional-radiative models and experimental data are analyzed with the aid of radiation-hydrodynamics calculations. When we apply isoelectronic techniques to the Nova experimental data, we find that the targets have electron temperatures of at least 3 keV.

  9. Electron temperature fluctuations associated with the weakly coherent mode in the edge of I-mode plasmas

    NASA Astrophysics Data System (ADS)

    White, A. E.; Phillips, P.; Whyte, D. G.; Hubbard, A. E.; Sung, C.; Hughes, J. W.; Dominguez, A.; Terry, J.; Cziegler, I.

    2011-11-01

    New measurements of electron temperature fluctuations associated with the weakly coherent mode (WCM) during improved mode, or I-mode plasmas (Whyte et al 2010 Nucl. Fusion. 50 105005) at Alcator C-Mod (Marmar et al 2007 Fusion. Sci. Technol. 51 3261) are presented in this paper. The measurements are made with a 32-channel, high-resolution profile electron cyclotron emission radiometer. The WCM electron temperature fluctuations are localized to a 1 cm region inside the last closed flux surface. The WCM electron temperature fluctuation level is measured in several different I-mode discharges and is in the range 1%<\\tilde T_e/T_e<2% , which is an order of magnitude smaller than the WCM density fluctuation level. The WCM edge fluctuations observed in I-mode are believed to play a role in increasing particle transport but not energy transport in the edge of I-mode plasmas. The large difference between normalized density and electron temperature fluctuation amplitudes provides new evidence that the WCM fluctuations can separately affect energy and particle transport.

  10. Non-invasive probe diagnostic method for electron temperature and ion current density in atmospheric pressure plasma jet source

    SciTech Connect

    Kim, Young-Cheol; Kim, Yu-Sin; Lee, Hyo-Chang; Moon, Jun-Hyeon; Chung, Chin-Wook; Kim, Yunjung; Cho, Guangsup

    2015-08-15

    The electrical probe diagnostics are very hard to be applied to atmospheric plasmas due to severe perturbation by the electrical probes. To overcome this, the probe for measuring electron temperature and ion current density is indirectly contacted with an atmospheric jet source. The plasma parameters are obtained by using floating harmonic analysis. The probe is mounted on the quartz tube that surrounds plasma. When a sinusoidal voltage is applied to a probe contacting on a quartz tube, the electrons near the sheath at dielectric tube are collected and the probe current has harmonic components due to probe sheath nonlinearity. From the relation of the harmonic currents and amplitude of the sheath voltage, the electron temperature near the wall can be obtained with collisional sheath model. The electron temperatures and ion current densities measured at the discharge region are in the ranges of 2.7–3.4 eV and 1.7–5.2 mA/cm{sup 2} at various flow rates and input powers.

  11. VUV diagnostics of electron impact processes in low temperature molecular hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Komppula, J.; Tarvainen, O.

    2015-08-01

    Novel methods for diagnostics of molecular hydrogen plasma processes, such as ionization, production of high vibrational levels, dissociation of molecules via excitation to singlet and triplet states and production of metastable states, are presented for molecular hydrogen plasmas in corona equilibrium. The methods are based on comparison of rate coefficients of plasma processes and optical emission spectroscopy of lowest singlet and triplet transitions, i.e. Lyman band ({{B}1}Σ\\text{u}+\\to {{X}1}Σ\\text{g}+ ) and molecular continuum ({{a}3}Σ\\text{g}+\\to {{b}3}Σ\\text{u}+ ), of the hydrogen molecule in the VUV wavelength range. Comparison of rate coefficients of spin-allowed and/or spin-forbidden excitations reduces the uncertainty caused by the non-equilibrium distributions of electron energy and molecular vibrational level, which are typically known poorly in plasma sources. The described methods are applied to estimate the rates of various plasma processes in a filament arc discharge.

  12. The effect of the electron temperature and current density profiles on the plasma current decay in JT-60U disruptions

    NASA Astrophysics Data System (ADS)

    Shibata, Y.; Isayama, A.; Miyamoto, S.; Kawakami, S.; Watanabe, K. Y.; Matsunaga, G.; Kawano, Y.; Lukash, V. E.; Khayrutdinov, R. R.; the JT-60 Team

    2014-04-01

    The plasma current decay during the initial phase of the current quench in JT-60U disruption has been calculated by a disruption simulation code (DINA) using the measured electron temperature Te profile. In the case of fast plasma current decay, Te has a peaked profile immediately after a thermal quench and the Te profile does not change significantly during the initial phase of the current quench. On the other hand, in the case of a slow plasma current decay, the Te profile is broader immediately after the thermal quench, and the Te profile shrinks. The results of the DINA simulation show that the plasma internal inductance Li increases during the initial phase of the current quench, whereas the plasma external inductance Le does not change over time. If the plasma is represented by a simple electrical circuit, the time derivative of Li functions as a resistance on the plasma current decay. It was confirmed that the increase in Li is caused by current diffusion toward the core plasma due to the decrease in Te in the intermediate and edge regions.

  13. The effects of nonthermal electron distributions on ion-temperature-gradient driven drift-wave instabilities in electron-ion plasma

    SciTech Connect

    Batool, Nazia; Masood, W.; Mirza, Arshad M.

    2012-08-15

    The effects of nonthermal electron distributions on electrostatic ion-temperature-gradient (ITG) driven drift-wave instabilities in the presence of equilibrium density, temperature, and magnetic field gradients are investigated here. By using Braginskii's transport equations for ions and Cairns as well as Kappa distribution for electrons, the coupled mode equations are derived. The modified ITG driven modes are derived, and it is found both analytically as well as numerically that the nonthermal distribution of electrons significantly modify the real frequencies as well as the growth rate of the ITG driven drift wave instability. The growth rate of ion-temperature-gradient driven instability is found to be maximum for Cairns, intermediate for Kappa, and minimum for the Maxwellian distributed electron case. The results of present investigation might be helpful to understand several wave phenomena in space and laboratory plasmas in the presence of nonthermal electrons.

  14. Kinetic Temperature and Electron Density Measurement in an Inductively Coupled Plasma Torch using Degenerate Four-Wave Mixing

    NASA Technical Reports Server (NTRS)

    Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.

    2008-01-01

    Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.

  15. Measurements of hot-electron temperature in laser-irradiated plasmas

    SciTech Connect

    Solodov, A. A.; Yaakobi, B.; Edgell, D. H.; Follett, R. K.; Myatt, J. F.; Sorce, C.; Froula, D. H.

    2016-10-26

    In a recently published work1–3 we reported on measuring the total energy of hot electrons produced by the interaction of a nanosecond laser with planar CH-coated molybdenum targets, using the Mo Kα emission. The temperature of the hot electrons in that work was determined by the high-energy bremsstrahlung [hard x-ray (HXR)] spectrum measured by a three-channel fluorescence-photomultiplier detector (HXRD). In the present work, we replaced the HXRD with a nine-channel image-plate (IP)–based detector (HXIP). For the same conditions (irradiance of the order of 1014 W/cm2; 2-ns pulses) the measured temperatures are consistently lower than those measured by the HXRD (by a factor ~1.5 to 1.7). In addition, we supplemented this measurement with three experiments that measure the hot-electron temperature using Kα line-intensity ratios from high-Z target layers, independent of the HXR emission. These experiments yielded temperatures that were consistent with those measured by the HXIP. We showed that the thermal x-ray radiation must be included in the derivation of total energy in hot electrons (Ehot), and that this makes Ehot only weakly dependent on hot-electron temperature. For a given x-ray emission in inertial confinement fusion compression experiments, this result would lead to a higher total energy in hot electrons, but the preheat of the compressed fuel may be lower because of the reduced hot-electron range.

  16. Measurements of hot-electron temperature in laser-irradiated plasmas

    DOE PAGES

    Solodov, A. A.; Yaakobi, B.; Edgell, D. H.; ...

    2016-10-26

    In a recently published work1–3 we reported on measuring the total energy of hot electrons produced by the interaction of a nanosecond laser with planar CH-coated molybdenum targets, using the Mo Kα emission. The temperature of the hot electrons in that work was determined by the high-energy bremsstrahlung [hard x-ray (HXR)] spectrum measured by a three-channel fluorescence-photomultiplier detector (HXRD). In the present work, we replaced the HXRD with a nine-channel image-plate (IP)–based detector (HXIP). For the same conditions (irradiance of the order of 1014 W/cm2; 2-ns pulses) the measured temperatures are consistently lower than those measured by the HXRD (bymore » a factor ~1.5 to 1.7). In addition, we supplemented this measurement with three experiments that measure the hot-electron temperature using Kα line-intensity ratios from high-Z target layers, independent of the HXR emission. These experiments yielded temperatures that were consistent with those measured by the HXIP. We showed that the thermal x-ray radiation must be included in the derivation of total energy in hot electrons (Ehot), and that this makes Ehot only weakly dependent on hot-electron temperature. For a given x-ray emission in inertial confinement fusion compression experiments, this result would lead to a higher total energy in hot electrons, but the preheat of the compressed fuel may be lower because of the reduced hot-electron range.« less

  17. TOPICAL REVIEW: Optical emission spectroscopy in low-temperature plasmas containing argon and nitrogen: determination of the electron temperature and density by the line-ratio method

    NASA Astrophysics Data System (ADS)

    Zhu, Xi-Ming; Pu, Yi-Kang

    2010-10-01

    This article reviews a variety of methods to obtain the electron temperature and density by the emission line ratios for low-temperature plasmas containing argon or nitrogen gas. Based on the collisional-radiative model of excited particles, the underlying principle of each of these methods is described, along with the criterion on how to select an appropriate line-ratio method according to the discharge conditions. Limitations on the application of each line-ratio technique are also discussed.

  18. Stark width and shift for electron number density diagnostics of low temperature plasma: Application to silicon Laser Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ivković, M.; Konjević, N.

    2017-05-01

    In this work we summarize, analyze and critically evaluate experimental procedures and results of LIBS electron number density plasma characterization using as examples Stark broadened Si I and Si II line profiles. Selected publications are covering the time period from very beginning of silicon LIBS studies until the end of the year 2015. To perform the analysis of experimental LIBS data, the testing of available semiclassical theoretical Stark broadening parameters for Si I and Si II lines was accomplished first. This is followed by the description of experimental setups, results and details of experimental procedure relevant for the line shape analysis of spectral lines used for plasma characterization. Although most of results and conclusions of this analysis are related to the application of silicon lines for LIBS characterization they are of general importance and may be applied to other elements and different low-temperature plasma sources. The analysis of experimental procedures used for LIBS diagnostics from emission profiles of non-hydrogenic spectral lines is carried out in the following order: the influence of laser ablation and crater formation, spatial and temporal plasma observation, line self-absorption and experimental profile deconvolution, the contribution of ion broadening in comparison with electron impacts contributions to the line width in case of neutral atom line and some other aspects of line shape analysis are considered. The application of Stark shift for LIBS diagnostics is demonstrated and discussed. Finally, the recommendations for an improvement of experimental procedures for LIBS electron number density plasma characterization are offered.

  19. Electron Temperature Fluctuations Associated with the Weakly Coherent Mode in the Edge of I-mode Plasmas

    NASA Astrophysics Data System (ADS)

    White, A. E.; Phillips, P.; Whyte, D. G.; Hubbard, A. E.; Sung, C.; Hughes, J. W.; Dominguez, A.; Terry, J.; Cziegler, I.

    2012-03-01

    New measurements of electron temperature fluctuations associated with the weakly coherent mode (WCM) during improved mode, or I-mode plasmas at Alcator C-Mod are presented in this poster [A. E. White, et al. Nuclear Fusion, 51, 113005 (2011)]. The measurements are made with a 32-channel, high-resolution profile ECE radiometer. The WCM electron temperature fluctuations are localized to a 1 cm region inside the last closed flux surface. The WCM electron temperature fluctuation level is measured in several different I-mode discharges and is in the range 1-2%, which is up to an order of magnitude smaller than the WCM density fluctuation level. The WCM edge fluctuations observed in I-mode are believed to play a role in increasing particle transport but not energy transport in the edge of I-mode plasmas. The large difference between normalized density and electron temperature fluctuation amplitudes provides new evidence that the WCM fluctuations can separately affect energy and particle transport.

  20. Cylindrical and spherical dust-ion-acoustic modified Gardner solitons in dusty plasmas with two-temperature superthermal electrons

    SciTech Connect

    Alam, M. S.; Masud, M. M.; Mamun, A. A.

    2013-12-15

    A rigorous theoretical investigation has been performed on the propagation of cylindrical and spherical Gardner solitons (GSs) associated with dust-ion-acoustic (DIA) waves in a dusty plasma consisting of inertial ions, negatively charged immobile dust, and two populations of kappa distributed electrons having two distinct temperatures. The well-known reductive perturbation method has been used to derive the modified Gardner (mG) equation. The basic features (amplitude, width, polarity, etc.) of nonplanar DIA modified Gardner solitons (mGSs) have been thoroughly examined by the numerical analysis of the mG equation. It has been found that the characteristics of the nonplanar DIA mGSs significantly differ from those of planar ones. It has been also observed that kappa distributed electrons with two distinct temperatures significantly modify the basic properties of the DIA solitary waves and that the plasma system under consideration supports both compressive and rarefactive DIA mGSs. The present investigation should play an important role for understanding localized electrostatic disturbances in space and laboratory dusty plasmas where stationary negatively charged dust, inertial ions, and superthermal electrons with two distinct temperatures are omnipresent ingredients.

  1. Spatial profiles of electron density, electron temperature, average ionic charge, and EUV emission of laser-produced Sn plasmas for EUV lithography

    NASA Astrophysics Data System (ADS)

    Sato, Yuta; Tomita, Kentaro; Tsukiyama, Syoichi; Eguchi, Toshiaki; Uchino, Kiichiro; Kouge, Kouichiro; Tomuro, Hiroaki; Yanagida, Tatsuya; Wada, Yasunori; Kunishima, Masahito; Kodama, Takeshi; Mizoguchi, Hakaru

    2017-03-01

    Spatial profiles of the electron density (n e), electron temperature (T e), and average ionic charge (Z) of laser-produced Sn plasmas for EUV lithography, whose conversion efficiency (CE) is sufficiently high for practical use, were measured using a collective Thomson scattering (TS) technique. For plasma production, Sn droplets of 26 µm diameter were used as a fuel. First, a picosecond-pulsed laser was used to expand a Sn target. Next, a CO2 laser was used to generate plasmas. By changing the injection timing of the picosecond and CO2 lasers, three different types of plasmas were generated. The CEs of the three types of plasmas differed, and ranged from 2.8 to 4.0%. Regarding the different plasma conditions, the spatial profiles of n e, T e, and Z clearly differed. However, under all plasma conditions, intense EUV was only observed at a sufficiently high T e (> 25 eV) and in an adequate n e range [1024–(2 × 1025) m‑3]. These plasma parameters lie in the efficient-EUV light source range, as predicted by simulations.

  2. Temperature and density evolution during decay in a 2.45 GHz hydrogen electron cyclotron resonance plasma: Off-resonant and resonant cases

    NASA Astrophysics Data System (ADS)

    Cortázar, O. D.; Megía-Macías, A.; Vizcaíno-de-Julián, A.

    2013-09-01

    Time resolved electron temperature and density measurements during the decay stage in a hydrogen electron cyclotron resonance (ECR) plasma are presented for a resonance and off-resonance magnetic field configurations. The measurements are conducted on a ECR plasma generator excited at 2.45 GHz denominated test-bench for ion-sources plasma studies at ESS Bilbao. The plasma parameters evolution is studied by Langmuir probe diagnostic with synchronized sample technique developed for repetitive pulsed plasmas with a temporal resolution of 200 ns in typical decay processes of about 40 μs. An afterglow transient is clearly observed in the reflected microwave power signal from the plasma. Simultaneously, the electron temperature evolution shows rebounding peaks that may be related to the interplay between density drop and microwave coupling with deep impact on the Electron Energy Distribution Function. The correlation of such structures with the plasma absorbed power and the coupling quality is also reported.

  3. Temperature and density evolution during decay in a 2.45 GHz hydrogen electron cyclotron resonance plasma: Off-resonant and resonant cases

    SciTech Connect

    Cortázar, O. D.

    2013-09-15

    Time resolved electron temperature and density measurements during the decay stage in a hydrogen electron cyclotron resonance (ECR) plasma are presented for a resonance and off-resonance magnetic field configurations. The measurements are conducted on a ECR plasma generator excited at 2.45 GHz denominated test-bench for ion-sources plasma studies at ESS Bilbao. The plasma parameters evolution is studied by Langmuir probe diagnostic with synchronized sample technique developed for repetitive pulsed plasmas with a temporal resolution of 200 ns in typical decay processes of about 40 μs. An afterglow transient is clearly observed in the reflected microwave power signal from the plasma. Simultaneously, the electron temperature evolution shows rebounding peaks that may be related to the interplay between density drop and microwave coupling with deep impact on the Electron Energy Distribution Function. The correlation of such structures with the plasma absorbed power and the coupling quality is also reported.

  4. Temperature and density evolution during decay in a 2.45 GHz hydrogen electron cyclotron resonance plasma: off-resonant and resonant cases.

    PubMed

    Cortázar, O D; Megía-Macías, A; Vizcaíno-de-Julián, A

    2013-09-01

    Time resolved electron temperature and density measurements during the decay stage in a hydrogen electron cyclotron resonance (ECR) plasma are presented for a resonance and off-resonance magnetic field configurations. The measurements are conducted on a ECR plasma generator excited at 2.45 GHz denominated test-bench for ion-sources plasma studies at ESS Bilbao. The plasma parameters evolution is studied by Langmuir probe diagnostic with synchronized sample technique developed for repetitive pulsed plasmas with a temporal resolution of 200 ns in typical decay processes of about 40 μs. An afterglow transient is clearly observed in the reflected microwave power signal from the plasma. Simultaneously, the electron temperature evolution shows rebounding peaks that may be related to the interplay between density drop and microwave coupling with deep impact on the Electron Energy Distribution Function. The correlation of such structures with the plasma absorbed power and the coupling quality is also reported.

  5. Gyrokinetic simulations of an electron temperature gradient turbulence driven current in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Yi, Sumin; Jhang, Hogun; Kwon, J. M.

    2016-10-01

    We report the results of a gyrokinetic simulation study elucidating the characteristics of the current driven by electron temperature gradient (ETG) turbulence in toroidal geometry. We examined the amount of the ETG turbulence-driven current for different turbulence levels, which were obtained by varying the relative electron gyroradius ρ* = ρe/a. Simulations show that the amount of the ETG turbulence-driven current increases with ρ* due to the gyro-Bohm scaling of turbulence intensity. A perturbation of the equilibrium q-profile by the ETG turbulence-driven current becomes noticeable when ρ* > 1/4000. Even in a small ρ* case, the proportional relation between the ETG turbulence-driven current and turbulence intensity suggests that a considerable intrinsic current can be driven inside an edge pedestal where a steep gradient of the electron temperature profile can excite ETG turbulence in a narrow region.

  6. Solar wind-driven variations of electron plasma sheet densities and temperatures beyond geostationary orbit during storm times

    NASA Astrophysics Data System (ADS)

    Dubyagin, S.; Ganushkina, N. Yu.; Sillanpää, I.; Runov, A.

    2016-09-01

    The empirical models of the plasma sheet electron temperature and density on the nightside at distances between 6 and 11 RE are constructed based on Time History of Events and Macroscale Interactions During Substorms (THEMIS) particle measurements. The data set comprises ˜400 h of observations in the plasma sheet during geomagnetic storm periods. The equatorial distribution of the electron density reveals a strong earthward gradient and a moderate variation with magnetic local time symmetric with respect to the midnight meridian. The electron density dependence on the external driving is parameterized by the solar wind proton density averaged over 4 h and the southward component of interplanetary magnetic field (IMF BS) averaged over 6 h. The interval of the IMF integration is much longer than a typical substorm growth phase, and it rather corresponds to the geomagnetic storm main phase duration. The solar wind proton density is the main controlling parameter, but the IMF BS becomes of almost the same importance in the near-Earth region. The root-mean-square deviation between the observed and predicted plasma sheet density values is 0.23 cm-3, and the correlation coefficient is 0.82. The equatorial distribution of the electron temperature has a maximum in the postmidnight to morning MLT sector, and it is highly asymmetric with respect to the local midnight. The electron temperature model is parameterized by solar wind velocity (averaged over 4 h), IMF BS (averaged over 45 min), and IMF BN (northward component of IMF, averaged over 2 h). The solar wind velocity is a major controlling parameter, and IMF BS and BN are comparable in importance. In contrast to the density model, the electron temperature shows higher correlation with the IMF BS averaged over ˜45 min (substorm growth phase time scale). The effect of BN manifests mostly in the outer part of the modeled region (r > 8RE). The influence of the IMF BS is maximal in the midnight to postmidnight MLT sector

  7. Measurement of N/sup +//sub 4/ recombination rate vs electron temperature in a proton beam created plasma

    SciTech Connect

    Fitaire, M.; Pointu, A.M.; Stathopoulos, D.; Vialle, M.

    1984-08-15

    An experimental method for studying electron--ion recombination process is described. It uses RF pulse heating of a plasma created by a proton beam in high pressure Ne:N/sub 2/ mixture. The recombination coefficient of N/sup +//sub 4/ ion has been determined to be (2.3 +- 0.5)10/sup -6/ (T/sub e//300)/sup() -0.53plus-or-minus0.14/ cm/sup 3/ s/sup -1/ for electron temperature T/sub e/ between 2000 and 11 000 K.

  8. Magnetic shear effects on plasma transport and turbulence at high electron to ion temperature ratio in DIII-D and JT-60U plasmas

    DOE PAGES

    Yoshida, Maiko; McKee, George R.; Murakami, Masanori; ...

    2017-03-30

    We demonstrated negative magnetic shear in DIII-D and JT-60U in order to mitigate the confinement degradation typically observed with increasing the electron to ion temperature ratio (T-e/T-i). In recent experiments in DIII-D negative central magnetic shear (NCS) discharges, the thermal transport in the internal transport barrier formed around the radius of the minimum safety factor (q(min)) remained almost constant and modestly increased in the region outside of q(min) compared to the positive shear (PS) case, when T-e/T-i increased from about 0.8 to 1.1 through electron cyclotron heating (ECH). The benefit of NCS extending into the region outside of qmin canmore » be explained by the lower magnetic shear in the NCS plasma over the plasma radius relative to the PS plasma. Reduced confinement degradation at high T-e/T-i with NCS plasmas was commonly observed in DIII-D and JT-60U. Furthermore, the mechanism of the different transport responses between the NCS and PS plasmas has been assessed in terms of fluctuation measurements and gyrokinetic simulations in DIII-D; NCS gave a smaller rise in the low-wavenumber broadband turbulent fluctuations with the increase in T-e/T-i compared with the PS case. This is consistent with gyrokinetic simulations, and this shows a smaller rise in the growth rates of the ion temperature gradient mode in the NCS plasmas, with increasing T-e/T-i. Gyrokinetic simulations also showed a change in the stability of the electron modes with ECH applied, consistent with higher-wavenumber fluctuation measurements, although more detailed simulations are needed to give a quantitative explanation for the experimental observations. Control of q-profile and magnetic shear will allow confinement improvement in future machines with dominant electron heating.« less

  9. Magnetic shear effects on plasma transport and turbulence at high electron to ion temperature ratio in DIII-D and JT-60U plasmas

    NASA Astrophysics Data System (ADS)

    Yoshida, M.; McKee, G. R.; Murakami, M.; Grierson, B. A.; Nakata, M.; Davis, E. M.; Marinoni, A.; Ono, M.; Rhodes, T. L.; Sung, C.; Schmitz, L.; Petty, C. C.; Ferron, J. R.; Turco, F.; Garofalo, A. M.; Holcomb, C. T.; Collins, C. M.; Solomon, W. M.

    2017-05-01

    Negative magnetic shear has been demonstrated in DIII-D and JT-60U to mitigate the confinement degradation typically observed with increasing the electron to ion temperature ratio (T e/T i). In recent experiments in DIII-D negative central magnetic shear (NCS) discharges, the thermal transport in the internal transport barrier formed around the radius of the minimum safety factor (q min) remained almost constant and modestly increased in the region outside of q min compared to the positive shear (PS) case, when T e/T i increased from about 0.8 to 1.1 through electron cyclotron heating (ECH). The benefit of NCS extending into the region outside of q min can be explained by the lower magnetic shear in the NCS plasma over the plasma radius relative to the PS plasma. Reduced confinement degradation at high T e/T i with NCS plasmas was commonly observed in DIII-D and JT-60U. The mechanism of the different transport responses between the NCS and PS plasmas has been assessed in terms of fluctuation measurements and gyrokinetic simulations in DIII-D; NCS gave a smaller rise in the low-wavenumber broadband turbulent fluctuations with the increase in T e/T i compared with the PS case. This is consistent with gyrokinetic simulations, which show a smaller rise in the growth rates of the ion temperature gradient mode in the NCS plasmas, with increasing T e/T i. Gyrokinetic simulations also showed a change in the stability of the electron modes with ECH applied, consistent with higher-wavenumber fluctuation measurements, although more detailed simulations are needed to give a quantitative explanation for the experimental observations. Control of q-profile and magnetic shear will allow confinement improvement in future machines with dominant electron heating.

  10. Determination of the Electron Density and Electron Temperature in A Magnetron Discharge Plasma Using Optical Spectroscopy and the Collisional-Radiative Model of Argon

    NASA Astrophysics Data System (ADS)

    Evdokimov, K. E.; Konishchev, M. E.; Pichugin, V. F.; Pustovalova, A. A.; Ivanova, N. M.; Sun', Ch.

    2017-09-01

    A method for determining the electron temperature and electron density in a plasma is proposed that is based on minimization of the difference between the experimental relative intensities of the spectral argon (Ar) lines and those same intensities calculated with the aid of the collisional-radiative model. The model describes the kinetics of the ground state and 40 excited states of the Ar atom and takes into account the following processes: excitation and deactivation of the states of the atom by electron impact, radiative decay of the excited states, self-absorption of radiation, ionization of excited states by electron impact, and quenching of metastable states as a consequence of collisions with the chamber walls. Using the given method, we have investigated the plasma of a magnetron discharge on a laboratory setup for intermediate-frequency magnetron sputtering for a few selected operating regimes.

  11. Ion-acoustic solitons in negative ion plasma with two-electron temperature distributions

    SciTech Connect

    Mishra, M. K.; Tiwari, R. S.; Chawla, J. K.

    2012-06-15

    Ion-acoustic solitons in a warm positive and negative ion species with different masses, concentrations, and charge states with two electron temperature distributions are studied. Using reductive perturbation method, Korteweg de-Vries (KdV) and modified-KdV (m-KdV) equations are derived for the system. The soliton solution of the KdV and m-KdV equations is discussed in detail. It is found that if the ions have finite temperatures, then there exist two types of modes, namely slow and fast ion-acoustic modes. It is also investigated that the parameter determining the nature of soliton (i.e., whether the system will support compressive or rarefactive solitons) is different for slow and fast modes. For the slow mode, the parameter is the relative temperature of the two ion species; whereas for the fast mode, it is the relative concentration of the two ion species. At a critical concentration of negative ions, both compressive and rarefactive solitons coexist. The amplitude and width of the solitons are discussed in detail at critical concentration for m-KdV solitons. The effect of the relative temperature of the two-electron and cold-electron concentration on the characteristics of the solitons are also discussed.

  12. Pulsed plasma electron sources

    SciTech Connect

    Krasik, Ya. E.; Yarmolich, D.; Gleizer, J. Z.; Vekselman, V.; Hadas, Y.; Gurovich, V. Tz.; Felsteiner, J.

    2009-05-15

    There is a continuous interest in research of electron sources which can be used for generation of uniform electron beams produced at E{<=}10{sup 5} V/cm and duration {<=}10{sup -5} s. In this review, several types of plasma electron sources will be considered, namely, passive (metal ceramic, velvet and carbon fiber with and without CsI coating, and multicapillary and multislot cathodes) and active (ferroelectric and hollow anodes) plasma sources. The operation of passive sources is governed by the formation of flashover plasma whose parameters depend on the amplitude and rise time of the accelerating electric field. In the case of ferroelectric and hollow-anode plasma sources the plasma parameters are controlled by the driving pulse and discharge current, respectively. Using different time- and space-resolved electrical, optical, spectroscopical, Thomson scattering and x-ray diagnostics, the parameters of the plasma and generated electron beam were characterized.

  13. Determination of electron temperature temporal evolution in laser-induced plasmas through Independent Component Analysis and 3D Boltzmann plot

    NASA Astrophysics Data System (ADS)

    Bredice, F.; Pacheco Martinez, P.; Sarmiento Mercado, R.; Sánchez-Aké, C.; Villagrán-Muniz, M.; Sirven, J. B.; El Rakwe, M.; Grifoni, E.; Legnaioli, S.; Lorenzetti, G.; Pagnotta, S.; Palleschi, V.

    2017-09-01

    In this paper we present the application of Independent Component Analysis to a set of time-resolved LIBS spectra, acquired on a brass sample at different delay times. The decomposition of the LIBS spectra in few Independent Components with a given temporal evolution is then exploited for obtaining the temporal evolution of the plasma electron temperature, through the application of the three-dimensional Boltzmann plot method recently proposed by the authors. This method allows the determination of the electron temperature temporal evolution without any knowledge of the spectral parameters (transition probability, degeneracy of the levels, etc.…) of the emitting lines. Only the knowledge of the energy of the upper level of the transition is required. The reduction of the LIBS spectral dataset to few Independent Components and associated proportions, further simplifies the determination of the plasma electron temperature temporal evolution, since the intensity of the emission lines does not need to be calculated. The results obtained are compared with the ones obtained using classical two-dimensional Boltzmann plot approach.

  14. Temperature Dependence of the Kinetic Energy of the Correlated Electron Plasma by Restricted Path-Integral Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Runge, Keith; Deymier, Pierre

    2013-03-01

    Recent progress in orbital-free Density Functional Theory (OF-DFT), particularly with regard to temperature dependent functionals, has promise for the simulation of warm dense matter (WDM) systems. WDM includes systems with densities of an order of magnitude beyond ambient or more and temperatures measured in kilokelvin. A challenge for the development of temperature dependent OF-DFT functionals is the lack of benchmark information with temperature and pressure dependence on simple models under WDM conditions. We present an approach to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Electrons are described as harmonic necklaces within the discrete path integral representation while quantum exchange takes the form of cross linking between electron necklaces. A molecular dynamics algorithm is used to sample phase space and the fermion sign problem is addressed by restricting the density matrix to positive values. The temperature dependence of kinetic energies for the strongly coupled electron plasma is presented for a number of Wigner-Seitz radii in terms of a fourth order Sommerfeld expansion. Supported by US DoE Grant DE-SC0002139

  15. Computational Study of Electron-Molecule Collisions Related to Low-Temperature Plasmas.

    NASA Astrophysics Data System (ADS)

    Huo, Winifred M.

    1997-10-01

    Computational study of electron-molecule collisions not only complements experimental measurements, but can also be used to investigate processes not readily accessible experimentally. A number of ab initio computational methods are available for this type of calculations. Here we describe a recently developed technique, the finite element Z-matrix method. Analogous to the R-matrix method, it partitions the space into regions and employs real matrix elements. However, unlike the implementation of the R-matrix method commonly used in atomic and molecular physics,(C. J. Gillan, J. Tennyson, and P. G. Burke, Chapter 10 in Computational Methods for Electron-Molecule Collisions), W. M. Huo and F. A. Gianturco, Editors, Plenum, New York (1995), p. 239. the Z-matrix method is fully variational.(D. Brown and J. C. Light, J. Chem. Phys. 101), 3723 (1994). In the present implementation, a mixed basis of finite elements and Gaussians is used to represent the continuum electron, thus offering full flexibility without imposing fixed boundary conditions. Numerical examples include the electron-impact dissociation of N2 via the metastable A^3Σ_u^+ state, a process which may be important in the lower thermosphere, and the dissociation of the CF radical, a process of interest to plasma etching. To understand the dissociation pathways, large scale quantum chemical calculations have been carried out for all target states which dissociate to the lowest five limits in the case of N_2, and to the lowest two limits in the case of CF. For N_2, the structural calculations clearly show the preference for predissociation if the initial state is the ground X^1Σ_g^+ state, but direct dissociation appears to be preferable if the initial state is the A^3Σ_u^+ state. Multi-configuration SCF target functions are used in the collisional calculation,

  16. Effects of ion-temperature on propagation of the large-amplitude ion-acoustic solitons in degenerate electron-positron-ion plasmas

    SciTech Connect

    Akbari-Moghanjoughi, M.

    2010-08-15

    Large-amplitude ion-acoustic solitary wave (IASW) propagation and matching criteria of existence of such waves are investigated in a degenerate dense electron-positron-ion plasma considering the ion-temperature as well as electron/positron degeneracy effects. It is shown that the ion-temperature effects play an important role in the existence criteria and allowed Mach-number range in such plasmas. Furthermore, a fundamental difference is remarked in the existence of supersonic IASW propagations between degenerate plasmas with nonrelativistic and ultrarelativistic electrons and positrons. Current study may be helpful in astrophysical as well as the laboratory inertial confinement fusion-research.

  17. Plasma electron analysis: Voyager plasma science experiment

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.

    1983-01-01

    The Plasma Science Experiment (PLS) on the Voyager spacecraft provide data on the plasma ions and electrons in the interplanetary medium and the magnetospheres of the giant planets Jupiter and Saturn. A description of the analysis used to obtain electron parameters (density, temperature, etc.) from the plasma science experiment PLS electron measurements which cover the energy range from 10 eV to 5950 eV is presented. The electron sensor (D cup) and its transmission characteristics are described. A derivation of the fundamental analytical expression of the reduced distribution function F(e) is given. The electron distribution function F(e), used in the moment integrations, can be derived from F(e). Positive ions produce a correction current (ion feedthrough) to the measured electron current, which can be important to the measurements of the suprathermal electron component. In the case of Saturn, this correction current, which can either add to or subtract from the measured electron current, is less than 20% of the measured signal at all times. Comments about the corrections introduced by spacecraft charging to the Saturn encounter data, which can be important in regions of high density and shadow when the spacecraft can become negatively charged are introduced.

  18. Computational Study of Electron-Molecule Collisions Related to Low-Temperature Plasmas

    NASA Technical Reports Server (NTRS)

    Huo, Winifred M.; Partridge, Harry (Technical Monitor)

    1997-01-01

    Computational study of electron-molecule collisions not only complements experimental measurements, but can also be used to investigate processes not readily accessible experimentally. A number of ab initio computational methods are available for these types of calculations. Here we describe a recently developed technique, the finite element Z-matrix method, Analogous to the R-matrix, method, it partitions the space into regions and employs real matrix elements. However, unlike the implementation of the R-matrix method commonly used in atomic and molecular physics, the Z-matrix method is fully variational. In the present implementation, a mixed basis of finite elements and Gaussians is used to represent the continuum electron, thus offering full flexibility without imposing fixed boundary conditions. Numerical examples include the electron-impact dissociation of N2 via the metastable A3Su+ state, a process which may be important in the lower thermosphere, and the dissociation of the CF radical, a process of interest to plasma etching. To understand the dissociation pathways, large scale quantum chemical calculations have been carried out for all target states which dissociate to the lowest five limits in the case of N2, and to the lowest two limits in the case of CF. For N2, the structural calculations clearly show the preference for predissociation if the initial state is the ground X1 Sg+ state, but direct dissociation appears to be preferable if the initial state is the A3Su+ state. Multi-configuration SCF target functions are used in the collisional calculation.

  19. Computational Study of Electron-Molecule Collisions Related to Low-Temperature Plasmas

    NASA Technical Reports Server (NTRS)

    Huo, Winifred M.; Partridge, Harry (Technical Monitor)

    1997-01-01

    Computational study of electron-molecule collisions not only complements experimental measurements, but can also be used to investigate processes not readily accessible experimentally. A number of ab initio computational methods are available for these types of calculations. Here we describe a recently developed technique, the finite element Z-matrix method, Analogous to the R-matrix, method, it partitions the space into regions and employs real matrix elements. However, unlike the implementation of the R-matrix method commonly used in atomic and molecular physics, the Z-matrix method is fully variational. In the present implementation, a mixed basis of finite elements and Gaussians is used to represent the continuum electron, thus offering full flexibility without imposing fixed boundary conditions. Numerical examples include the electron-impact dissociation of N2 via the metastable A3Su+ state, a process which may be important in the lower thermosphere, and the dissociation of the CF radical, a process of interest to plasma etching. To understand the dissociation pathways, large scale quantum chemical calculations have been carried out for all target states which dissociate to the lowest five limits in the case of N2, and to the lowest two limits in the case of CF. For N2, the structural calculations clearly show the preference for predissociation if the initial state is the ground X1 Sg+ state, but direct dissociation appears to be preferable if the initial state is the A3Su+ state. Multi-configuration SCF target functions are used in the collisional calculation.

  20. Measurements of electron density and temperature profiles in plasma produced by Nike KrF laser for laser plasma instability research

    NASA Astrophysics Data System (ADS)

    Oh, Jaechul; Weaver, J. L.; Karasik, M.; Chan, L. Y.

    2015-08-01

    A grid image refractometer (GIR) has been implemented at the Nike krypton fluoride laser facility of the Naval Research Laboratory. This instrument simultaneously measures propagation angles and transmissions of UV probe rays (λ = 263 nm, Δt = 10 ps) refracted through plasma. We report results of the first Nike-GIR measurement on a CH plasma produced by the Nike laser pulse (˜1 ns FWHM) with the intensity of 1.1 × 1015 W/cm2. The measured angles and transmissions were processed to construct spatial profiles of electron density (ne) and temperature (Te) in the underdense coronal region of the plasma. Using an inversion algorithm developed for the strongly refracted rays, the deployed GIR system probed electron densities up to 4 × 1021 cm-3 with the density scale length of 120 μm along the plasma symmetry axis. The resulting ne and Te profiles are verified to be self-consistent with the measured quantities of the refracted probe light.

  1. Molecular dynamics simulations and generalized Lenard-Balescu calculations of electron-ion temperature equilibration in plasmas

    NASA Astrophysics Data System (ADS)

    Benedict, Lorin X.; Surh, Michael P.; Castor, John I.; Khairallah, Saad A.; Whitley, Heather D.; Richards, David F.; Glosli, James N.; Murillo, Michael S.; Scullard, Christian R.; Grabowski, Paul E.; Michta, David; Graziani, Frank R.

    2012-10-01

    We study the problem of electron-ion temperature equilibration in plasmas. We consider pure H at various densities and temperatures and Ar-doped H at temperatures high enough so that the Ar is fully ionized. Two theoretical approaches are used: classical molecular dynamics (MD) with statistical two-body potentials and a generalized Lenard-Balescu (GLB) theory capable of treating multicomponent weakly coupled plasmas. The GLB is used in two modes: (1) with the quantum dielectric response in the random-phase approximation (RPA) together with the pure Coulomb interaction and (2) with the classical (ℏ→0) dielectric response (both with and without local-field corrections) together with the statistical potentials. We find that the MD results are described very well by classical GLB including the statistical potentials and without local-field corrections (RPA only); worse agreement is found when static local-field effects are included, in contradiction to the classical pure-Coulomb case with like charges. The results of the various approaches are all in excellent agreement with pure-Coulomb quantum GLB when the temperature is high enough. In addition, we show that classical calculations with statistical potentials derived from the exact quantum two-body density matrix produce results in far better agreement with pure-Coulomb quantum GLB than classical calculations performed with older existing statistical potentials.

  2. Plasma heating power dissipation in low temperature hydrogen plasmas

    SciTech Connect

    Komppula, J. Tarvainen, O.

    2015-10-15

    A theoretical framework for power dissipation in low temperature plasmas in corona equilibrium is developed. The framework is based on fundamental conservation laws and reaction cross sections and is only weakly sensitive to plasma parameters, e.g., electron temperature and density. The theory is applied to low temperature atomic and molecular hydrogen laboratory plasmas for which the plasma heating power dissipation to photon emission, ionization, and chemical potential is calculated. The calculated photon emission is compared to recent experimental results.

  3. Determination of electron density and temperature in non-LTE plasmas from spectral lines of impurity ions

    NASA Technical Reports Server (NTRS)

    Kunc, Joseph A.

    1988-01-01

    A novel approach for calculating the populations of the excited Li-like ions C IV, N V, O VI, and Ne VIII is presented. The populations of the 2(2P), 3(2S), 3(2P), and 3(2D) electronic levels in these ions in optically thin plasmas with a broad range of electron density, N(e), and temperature, T(e), are determined from the collisional-radiative model by solving the system of rate equations for the production of excited ions; the equations are linear with respect to the excited ion populations, and the N(e) and T(e) are taken as independent variables. These populations are used to determine the ratios of line intensities for dipole allowed transitions between various energy levels. This approach can be applied to impurities other than the lithiumlike ions and is especially useful for diagnostics of systems where nonintrusive spectroscopic techniques must be used.

  4. Reduced model prediction of electron temperature profiles in microtearing-dominated National Spherical Torus eXperiment plasmas

    SciTech Connect

    Kaye, S. M. Guttenfelder, W.; Bell, R. E.; Gerhardt, S. P.; LeBlanc, B. P.; Maingi, R.

    2014-08-15

    A representative H-mode discharge from the National Spherical Torus eXperiment is studied in detail to utilize it as a basis for a time-evolving prediction of the electron temperature profile using an appropriate reduced transport model. The time evolution of characteristic plasma variables such as β{sub e}, ν{sub e}{sup ∗}, the MHD α parameter, and the gradient scale lengths of T{sub e}, T{sub i}, and n{sub e} were examined as a prelude to performing linear gyrokinetic calculations to determine the fastest growing micro instability at various times and locations throughout the discharge. The inferences from the parameter evolutions and the linear stability calculations were consistent. Early in the discharge, when β{sub e} and ν{sub e}{sup ∗} were relatively low, ballooning parity modes were dominant. As time progressed and both β{sub e} and ν{sub e}{sup ∗} increased, microtearing became the dominant low-k{sub θ} mode, especially in the outer half of the plasma. There are instances in time and radius, however, where other modes, at higher-k{sub θ}, may, in addition to microtearing, be important for driving electron transport. Given these results, the Rebut-Lallia-Watkins (RLW) electron thermal diffusivity model, which is based on microtearing-induced transport, was used to predict the time-evolving electron temperature across most of the profile. The results indicate that RLW does a good job of predicting T{sub e} for times and locations where microtearing was determined to be important, but not as well when microtearing was predicted to be stable or subdominant.

  5. Reduced model prediction of electron temperature profiles in microtearing-dominated National Spherical Torus eXperiment plasmas

    SciTech Connect

    Kaye, S. M.; Guttenfelder, W.; Bell, R. E.; Gerhardt, S. P.; LeBlanc, B. P.; Maingi, R.

    2014-08-01

    A representative H-mode discharge from the National Spherical Torus eXperiment is studied in detail to utilize it as a basis for a time-evolving prediction of the electron temperature profile using an appropriate reduced transport model. The time evolution of characteristic plasma variables such as βe, ν*e, the MHD α parameter, and the gradient scale lengths of Te, Ti, and ne were examined as a prelude to performing linear gyrokinetic calculations to determine the fastest growing micro instability at various times and locations throughout the discharge. The inferences from the parameter evolutions and the linear stability calculations were consistent. Early in the discharge, when βe and ν*e were relatively low, ballooning parity modes were dominant. As time progressed and both βe and ν*e increased, microtearing became the dominant low-κθ mode, especially in the outer half of the plasma. There are instances in time and radius, however, where other modes, at higher-κθ, may, in addition to microtearing, be important for driving electron transport. Given these results, the Rebut-Lallia-Watkins (RLW) electron thermal diffusivity model, which is based on microtearing-induced transport, was used to predict the time-evolving electron temperature across most of the profile. The results indicate that RLW does a good job of predicting Te for times and locations where microtearing was determined to be important, but not as well when microtearing was predicted to be stable or subdominant.

  6. Electron Bernstein wave electron temperature profile diagnostic

    SciTech Connect

    G. Taylor; P. Efthimion; B. Jones; T. Munsat; J. Spaleta; J. Hosea; R. Kaita; R. Majeski; J. Menard

    2000-07-20

    Electron cyclotron emission (ECE) has been employed as a standard electron temperature profile diagnostic on many tokamaks and stellarators, but most magnetically confined plasma devices cannot take advantage of standard ECE diagnostics to measure temperature. They are either overdense, operating at high density relative to the magnetic field (e.g. where the plasma frequency is much greater than the electron cyclotron frequency, as in a spherical torus) or they have insufficient density and temperature to reach the blackbody condition. Electron Bernstein waves (EBWs) are electrostatic waves that can propagate in overdense plasmas and have a high optical thickness at the electron cyclotron resonance layers, as a result of their large perpendicular wavenumber. This paper reports on measurements of EBW emission on the CDX-U spherical torus, where B{sub o} {approximately} 2 kG, {approximately}10{sup 13} cm{sup {minus}3} and T{sub e} {approx} to 10 -- 200 eV. Results are presented for electromagnetic measurements of EBW emission, mode-converted near the plasma edge. The EBW emission was absolutely calibrated and compared to the electron temperature profile measured by a multi-point Thomson scattering diagnostic. Depending on the plasma conditions, the mode converted EBW radiation temperature was found to be less than or equal to T{sub e} and the emission source was determined to be radially localized at the electron cyclotron resonance layer. A Langmuir triple probe and a 140 GHz interferometer were employed to measure changes in edge density profile in the vicinity of the upper hybrid resonance, where the mode conversion of the EBWs is expected to occur. Initial results suggest EBW emission and EBW heating are viable concepts for overdense plasmas.

  7. Temperature and Electron Density Determination on Laser-Induced Breakdown Spectroscopy (LIBS) Plasmas: A Physical Chemistry Experiment

    ERIC Educational Resources Information Center

    Najarian, Maya L.; Chinni, Rosemarie C.

    2013-01-01

    This laboratory is designed for physical chemistry students to gain experience using laser-induced breakdown spectroscopy (LIBS) in understanding plasma diagnostics. LIBS uses a high-powered laser that is focused on the sample causing a plasma to form. The emission of this plasma is then spectrally resolved and detected. Temperature and electron…

  8. Temperature and Electron Density Determination on Laser-Induced Breakdown Spectroscopy (LIBS) Plasmas: A Physical Chemistry Experiment

    ERIC Educational Resources Information Center

    Najarian, Maya L.; Chinni, Rosemarie C.

    2013-01-01

    This laboratory is designed for physical chemistry students to gain experience using laser-induced breakdown spectroscopy (LIBS) in understanding plasma diagnostics. LIBS uses a high-powered laser that is focused on the sample causing a plasma to form. The emission of this plasma is then spectrally resolved and detected. Temperature and electron…

  9. Imaging spectroscopy diagnosis of internal electron temperature and density distributions of plasma cloud surrounding hydrogen pellet in the Large Helical Device

    SciTech Connect

    Motojima, G.; Sakamoto, R.; Goto, M.; Matsuyama, A.; Yamada, H.; Mishra, J. S.

    2012-09-15

    To investigate the behavior of hydrogen pellet ablation, a novel method of high-speed imaging spectroscopy has been used in the Large Helical Device (LHD) for identifying the internal distribution of the electron density and temperature of the plasma cloud surrounding the pellet. This spectroscopic system consists of a five-branch fiberscope and a fast camera, with each objective lens having a different narrow-band optical filter for the hydrogen Balmer lines and the background continuum radiation. The electron density and temperature in the plasma cloud are obtained, with a spatial resolution of about 6 mm and a temporal resolution of 5 Multiplication-Sign 10{sup -5} s, from the intensity ratio measured through these filters. To verify the imaging, the average electron density and temperature also have been measured from the total emission by using a photodiode, showing that both density and temperature increase with time during the pellet ablation. The electron density distribution ranging from 10{sup 22} to 10{sup 24} m{sup -3} and the temperature distribution around 1 eV have been observed via imaging. The electron density and temperature of a 0.1 m plasma cloud are distributed along the magnetic field lines and a significant electron pressure forms in the plasma cloud for typical experimental conditions of the LHD.

  10. Imaging spectroscopy diagnosis of internal electron temperature and density distributions of plasma cloud surrounding hydrogen pellet in the Large Helical Device.

    PubMed

    Motojima, G; Sakamoto, R; Goto, M; Matsuyama, A; Mishra, J S; Yamada, H

    2012-09-01

    To investigate the behavior of hydrogen pellet ablation, a novel method of high-speed imaging spectroscopy has been used in the Large Helical Device (LHD) for identifying the internal distribution of the electron density and temperature of the plasma cloud surrounding the pellet. This spectroscopic system consists of a five-branch fiberscope and a fast camera, with each objective lens having a different narrow-band optical filter for the hydrogen Balmer lines and the background continuum radiation. The electron density and temperature in the plasma cloud are obtained, with a spatial resolution of about 6 mm and a temporal resolution of 5 × 10(-5) s, from the intensity ratio measured through these filters. To verify the imaging, the average electron density and temperature also have been measured from the total emission by using a photodiode, showing that both density and temperature increase with time during the pellet ablation. The electron density distribution ranging from 10(22) to 10(24) m(-3) and the temperature distribution around 1 eV have been observed via imaging. The electron density and temperature of a 0.1 m plasma cloud are distributed along the magnetic field lines and a significant electron pressure forms in the plasma cloud for typical experimental conditions of the LHD.

  11. Effects of solar wind ultralow-frequency fluctuations on plasma sheet electron temperature: Regression analysis with support vector machine

    NASA Astrophysics Data System (ADS)

    Wang, Chih-Ping; Kim, Hee-Jeong; Yue, Chao; Weygand, James M.; Hsu, Tung-Shin; Chu, Xiangning

    2017-04-01

    To investigate whether ultralow-frequency (ULF) fluctuations from 0.5 to 8.3 mHz in the solar wind and interplanetary magnetic field (IMF) can affect the plasma sheet electron temperature (Te) near geosynchronous distances, we use a support vector regression machine technique to decouple the effects from different solar wind parameters and their ULF fluctuation power. Te in this region varies from 0.1 to 10 keV with a median of 1.3 keV. We find that when the solar wind ULF power is weak, Te increases with increasing southward IMF Bz and solar wind speed, while it varies weakly with solar wind density. As the ULF power becomes stronger during weak IMF Bz ( 0) or northward IMF, Te becomes significantly enhanced, by a factor of up to 10. We also find that mesoscale disturbances in a time scale of a few to tens of minutes as indicated by AE during substorm expansion and recovery phases are more enhanced when the ULF power is stronger. The effect of ULF powers may be explained by stronger inward radial diffusion resulting from stronger mesoscale disturbances under higher ULF powers, which can bring high-energy plasma sheet electrons further toward geosynchronous distance. This effect of ULF powers is particularly important during weak southward IMF or northward IMF when convection electric drift is weak.

  12. A simple far-infrared laser interferometer for measuring electron densities in reactive low-temperature plasmas

    SciTech Connect

    Pargmann, C.; Singh, S.V.; Soltwisch, H.

    2005-11-15

    A sensitive far-infrared (fir) interferometer for electron density measurements in reactive low-temperature plasmas is described. The instrument is based on an optically pumped fir laser (wavelength range 50-600 {mu}m depending on the working gas) and makes use of the nonlinear relation between output power and cavity loss. The fir beam, which leaves the resonator through a coupling hole in the end mirror, is reflected back into the cavity, such that the coupling hole behaves like a variable 'leak' with a loss rate depending on the phase of the reentering wave relative to the standing wave within the resonator. As a result of the feedback, the output intensity undergoes strong nonlinear variations if the optical distance of the external mirror is changed by small amounts, {delta}z. The power variation is monitored through a small opening in the external mirror. Test experiments using a wavelength of 432.6 {mu}m and a Schottky-diode detector have yielded a minimum detectable pathlength variation of {delta}z=0.4 {mu}m, corresponding to a change of the line-integrated electron density n{sub e}xL of about 5x10{sup 15} m{sup -2}. A first application to argon plasmas in inductively coupled rf discharges has been made, and the results have been compared to concomitant Langmuir probe measurements.

  13. Molecular dynamics studies of electron-ion temperature equilibration in hydrogen plasmas within the coupled-mode regime

    NASA Astrophysics Data System (ADS)

    Benedict, Lorin X.; Surh, Michael P.; Stanton, Liam G.; Scullard, Christian R.; Correa, Alfredo A.; Castor, John I.; Graziani, Frank R.; Collins, Lee A.; Čertík, Ondřej; Kress, Joel D.; Murillo, Michael S.

    2017-04-01

    We use classical molecular dynamics (MD) to study electron-ion temperature equilibration in two-component plasmas in regimes for which the presence of coupled collective modes has been predicted to substantively reduce the equilibration rate. Guided by previous kinetic theory work, we examine hydrogen plasmas at a density of n =1026cm-3 , Ti=105K , and 107K temperature equation of state, and (ii) a notable deviation in the energy equilibration rate when compared to calculations from classical Lenard-Balescu theory including the QSPs. In particular, it is shown that the energy equilibration rates from MD are more similar to those of the theory when coupled modes are neglected. We suggest possible reasons for this surprising result and propose directions of further research along these lines.

  14. Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser-produced plasma ions acceleration.

    PubMed

    Sakaki, H; Nishiuchi, M; Maeda, S; Sagisaka, A; Pirozhkov, A S; Pikuz, T; Faenov, A; Ogura, K; Fukami, T; Matsukawa, K; Kanasaki, M; Fukuda, Y; Yogo, A; Esirkepov, T; Kiriyama, H; Shimomura, T; Nakai, Y; Tanoue, M; Torimoto, K; Okamoto, M; Sato, T; Niita, K; Tamura, J; Nishio, K; Sako, H; Yamauchi, T; Watanabe, Y; Bulanov, S; Kondo, K

    2014-02-01

    High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams, such as high-energy proton and ions with high charge to mass ratio (Q/M; same as multi-charged ions). Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity of 1 × 10(21) W/cm(2) on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR-39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System. The results obtained provide useful approach for analyzing the various laser based ion beams.

  15. Existence domain of the compressive ion acoustic super solitary wave in a two electron temperature warm multi-ion plasma

    NASA Astrophysics Data System (ADS)

    Steffy, S. V.; Ghosh, S. S.

    2017-10-01

    The transition of an ion acoustic solitary wave into a "supersoliton," or a super solitary wave have been explored in a two electron temperature warm multi-ion plasma using the Sagdeev pseudopotential technique. It is generally believed that the ion acoustic solitary wave can be transformed to a super solitary wave only through a double layer. The present work shows that the transition route of an ion acoustic solitary wave to a super solitary wave is not unique. Depending on the electron temperature ratio, a regular solitary wave may transform to a super solitary wave either via the double layer, or through an extra-nonlinear solitary structure whose morphology differs from that of a regular one. These extra-nonlinear structures are associated with a fluctuation of the charge separation within the potential profile and are named as "variable solitary waves." Depending on these analyses, the upper and lower bounds of a super solitary wave have been deciphered and its existence domain has been delineated in the parametric space. It reveals that super solitary waves are a subset of a more generalized class of extra-nonlinear solitary structures called variable solitary waves.

  16. Low Temperature Plasma Medicine

    NASA Astrophysics Data System (ADS)

    Graves, David

    2013-10-01

    Ionized gas plasmas near room temperature are used in a remarkable number of technological applications mainly because they are extraordinarily efficient at exploiting electrical power for useful chemical and material transformations near room temperature. In this tutorial address, I will focus on the newest area of low temperature ionized gas plasmas (LTP), in this case operating under atmospheric pressure conditions, in which the temperature-sensitive material is living tissue. LTP research directed towards biomedical applications such as sterilization, surgery, wound healing and anti-cancer therapy has seen remarkable growth in the last 3-5 years, but the mechanisms responsible for the biomedical effects have remained mysterious. It is known that LTP readily create reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS (or RONS), in addition to a suite of other radical and non-radical reactive species, are essential actors in an important sub-field of aerobic biology termed ``redox'' (or oxidation-reduction) biology. I will review the evidence suggesting that RONS generated by plasmas are responsible for their observed therapeutic effects. Other possible bio-active mechanisms include electric fields, charges and photons. It is common in LTP applications that synergies between different mechanisms can play a role and I will review the evidence for synergies in plasma biomedicine. Finally, I will address the challenges and opportunities for plasma physicists to enter this novel, multidisciplinary field.

  17. Temporal variations of electron density and temperature in Kr/Ne/H2 photoionized plasma induced by nanosecond pulses from extreme ultraviolet source

    NASA Astrophysics Data System (ADS)

    Saber, I.; Bartnik, A.; Wachulak, P.; Skrzeczanowski, W.; Jarocki, R.; Fiedorowicz, H.

    2017-06-01

    Spectral investigations of low-temperature photoionized plasmas created in a Kr/Ne/H2 gas mixture were performed. The low-temperature plasmas were generated by gas mixture irradiation using extreme ultraviolet pulses from a laser-plasma source. Emission spectra in the ultraviolet/visible range from the photoionized plasmas contained lines that mainly corresponded to neutral atoms and singly charged ions. Temporal variations in the plasma electron temperature and electron density were studied using different characteristic emission lines at various delay times. Results, based on Kr II lines, showed that the electron temperature decreased from 1.7 to 0.9 eV. The electron densities were estimated using different spectral lines at each delay time. In general, except for the Hβ line, in which the electron density decreased from 3.78 × 1016 cm-3 at 200 ns to 5.77 × 1015 cm-3 at 2000 ns, most of the electron density values measured from the different lines were of the order of 1015 cm-3 and decreased slightly while maintaining the same order when the delay time increased. The time dependences of the measured and simulated intensities of a spectral line of interest were also investigated. The validity of the partial or full local thermodynamic equilibrium (LTE) conditions in plasma was explained based on time-resolved electron density measurements. The partial LTE condition was satisfied for delay times in the 200 ns to 1500 ns range. The results are summarized, and the dominant basic atomic processes in the gas mixture photoionized plasma are discussed.

  18. Effects of finite beam and plasma temperature on the growth rate of a two-stream free electron laser with background plasma

    SciTech Connect

    Mahdizadeh, N.; Aghamir, F. M.

    2013-02-28

    A fluid theory is used to derive the dispersion relation of two-stream free electron laser (TSFEL) with a magnetic planar wiggler pump in the presence of background plasma (BP). The effect of finite beams and plasma temperature on the growth rate of a TSFEL has been verified. The twelve order dispersion equation has been solved numerically. Three instabilities, FEL along with the TS and TS-FEL instabilities occur simultaneously. The analysis in the case of cold BP shows that when the effect of the beam temperature is taken into account, both instable bands of wave-number and peak growth rate in the TS instability increase, but peak growth of the FEL and TS-FEL instabilities decreases. Thermal motion of the BP causes to diminish the TS instability and it causes to decrease the FEL and TS-FEL instabilities. By increasing the beam densities and lowering initial velocities (in the collective Raman regime), growth rate of instabilities increases; however, it has opposite behavior in the Campton regime.

  19. Electron temperature measurements inside the ablating plasma of gas-filled hohlraums at the National Ignition Facility

    SciTech Connect

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brown, G. V.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.; Regan, S. P.; Jaquez, J.; Huang, H.; Hansen, S. B.

    2016-05-15

    The first measurement of the electron temperature (T{sub e}) inside a National Ignition Facility hohlraum is obtained using temporally resolved K-shell X-ray spectroscopy of a mid-Z tracer dot. Both isoelectronic- and interstage-line ratios are used to calculate the local T{sub e} via the collisional–radiative atomic physics code SCRAM [Hansen et al., High Energy Density Phys 3, 109 (2007)]. The trajectory of the mid-Z dot as it is ablated from the capsule surface and moves toward the laser entrance hole (LEH) is measured using side-on x-ray imaging, characterizing the plasma flow of the ablating capsule. Data show that the measured dot location is farther away from the LEH in comparison to the radiation-hydrodynamics simulation prediction using HYDRA [Marinak et al., Phys. Plasmas 3, 2070 (1996)]. To account for this discrepancy, the predicted simulation T{sub e} is evaluated at the measured dot trajectory. The peak T{sub e}, measured to be 4.2 keV ± 0.2 keV, is ∼0.5 keV hotter than the simulation prediction.

  20. Extraction of the spatial distribution of electron temperature and density in Magnetized Liner Inertial Fusion implosion plasmas

    NASA Astrophysics Data System (ADS)

    Carpenter, Kyle; Mancini, Roberto

    2016-10-01

    We are testing polychromatic tomography to extract the spatial distribution of electron temperatures and densities in the cylindrical implosion plasmas created during MagLIF. Motivation for this technique stems from its successful application to spherical implosion core plasmas on Omega through the analysis of spatially resolved spectra (SRS) collected via pinhole imaging. In MagLIF, collections of SRS can be extracted from the images created by the slit imaging CRITR spectrometers. These spectra can be complemented with pinhole monochromatic images and spectra recorded with a spherical crystal spectrometer. One axially resolved and one radially resolved CRITR are field during MagLIF and information extracted from one of these SRS would be spatially integrated over a plane of finite thickness given by the spatial resolution of the instrument. In our method, we couple a model that creates synthetic sets of spectra, like those obtained from an experiment, with a Pareto genetic algorithm which searches in parameter space for the spatial distribution which best simultaneously and self-consistently fits the set of SRS/ Solutions obtained are used as the initial solution for a Levenberg-Marquadt minimization algorithm to provide a final ``fine-tuned'' solution. We are testing this method by creating synthetic ``experimental'' data and using the technique to search for the spatial distribution. The results of these feasibility studies will be discussed. The work is supported by a contract from Sandia National Laboratories.

  1. Electron temperature measurements inside the ablating plasma of gas-filled hohlraums at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brown, G. V.; Regan, S. P.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Jaquez, J.; Huang, H.; Hansen, S. B.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.

    2016-05-01

    The first measurement of the electron temperature (Te) inside a National Ignition Facility hohlraum is obtained using temporally resolved K-shell X-ray spectroscopy of a mid-Z tracer dot. Both isoelectronic- and interstage-line ratios are used to calculate the local Te via the collisional-radiative atomic physics code SCRAM [Hansen et al., High Energy Density Phys 3, 109 (2007)]. The trajectory of the mid-Z dot as it is ablated from the capsule surface and moves toward the laser entrance hole (LEH) is measured using side-on x-ray imaging, characterizing the plasma flow of the ablating capsule. Data show that the measured dot location is farther away from the LEH in comparison to the radiation-hydrodynamics simulation prediction using HYDRA [Marinak et al., Phys. Plasmas 3, 2070 (1996)]. To account for this discrepancy, the predicted simulation Te is evaluated at the measured dot trajectory. The peak Te, measured to be 4.2 keV ± 0.2 keV, is ˜0.5 keV hotter than the simulation prediction.

  2. Three dimensional dust-acoustic solitary waves in an electron depleted dusty plasma with two-superthermal ion-temperature

    SciTech Connect

    Borhanian, J.; Shahmansouri, M.

    2013-01-15

    A theoretical investigation is carried out to study the existence and characteristics of propagation of dust-acoustic (DA) waves in an electron-depleted dusty plasma with two-temperature ions, which are modeled by kappa distribution functions. A three-dimensional cylindrical Kadomtsev-Petviashvili equation governing evolution of small but finite amplitude DA waves is derived by means of a reductive perturbation method. The influence of physical parameters on solitary wave structure is examined. Furthermore, the energy integral equation is used to study the existence domains of the localized structures. It is found that the present model can be employed to describe the existence of positive as well as negative polarity DA solitary waves by selecting special values for parameters of the system, e.g., superthermal index of cold and/or hot ions, cold to hot ion density ratio, and hot to cold ion temperature ratio. This model may be useful to understand the excitation of nonlinear DA waves in astrophysical objects.

  3. Linear interaction and relative role of the ion temperature gradient and trapped electron modes in the reactor-relevant finite beta plasma condition

    NASA Astrophysics Data System (ADS)

    Kim, J. Y.; Han, H. S.

    2017-07-01

    Focusing on the reactor-relevant plasma condition, where electrons and ions are expected to have a similar temperature profile, an estimate is given on the relative role of the ion temperature gradient (ITG) and trapped electron mode (TEM). A local kinetic code, which takes into account the collisional and electromagnetic effects, is utilized for the linear stability comparison between the two modes. It is shown that, when we limit our consideration to the ion-scale wavelength regime, the TEM, usually driven by the electron temperature gradient, is sub-dominant compared to the ITG in the most parameter regime, including plasma beta. The asymmetric interaction between the ITG and the TEM, in addition to the smaller fraction of trapped electrons and the collisional effect, is found to play a central role in producing this result. When we include the density gradient driven TEM, a strong interaction is also observed, with the mode being rapidly stabilized or transited to the electron temperature gradient driven TEM (ITG) as the electron (ion) temperature gradient increases. Based on these results on the linear interaction and relative role of the ITG and the two types of TEM, a brief discussion is presented on the possible evolution of temperature and density profiles in reactor-relevant conditions.

  4. Time-fractional KdV equation for plasma of two different temperature electrons and stationary ion

    SciTech Connect

    El-Wakil, S. A.; Abulwafa, Essam M.; El-Shewy, E. K.; Mahmoud, Abeer A.

    2011-09-15

    Using the time-fractional KdV equation, the nonlinear properties of small but finite amplitude electron-acoustic solitary waves are studied in a homogeneous system of unmagnetized collisionless plasma. This plasma consists of cold electrons fluid, non-thermal hot electrons, and stationary ions. Employing the reductive perturbation technique and the Euler-Lagrange equation, the time-fractional KdV equation is derived and it is solved using variational method. It is found that the time-fractional parameter significantly changes the soliton amplitude of the electron-acoustic solitary waves. The results are compared with the structures of the broadband electrostatic noise observed in the dayside auroral zone.

  5. Effect of surface temperature on plasma-surface interactions in an inductively coupled modified gaseous electronics conference reactor

    SciTech Connect

    Zhou Baosuo; Joseph, Eric A.; Sant, Sanket P.; Liu Yonghua; Radhakrishnan, Arun; Overzet, Lawrence J.; Goeckner, Matthew J.

    2005-11-15

    The effect of wall temperature, from 50 to 200 deg. C, on gas phase chemistry and substrate etching rates has been studied in inductively coupled CF{sub 4} plasma under two distinctive initial wall conditions, namely 'clean' and 'seasoned'. During plasma etching, we found that the gas phase chemistry exhibits a weak dependence on the initial wall cleanliness when the wall is either cold (50 deg. C) or hot (200 deg. C). In the mid-temperature range, the wall cleanliness can strongly affect gas phase chemistry. The study of temperature dependence of the fluorocarbon film deposition on the substrate indicates that ion-assisted incorporation, direct ion incorporation and ion-assisted desorption are the major factors determining film growth and removal. Ion-assisted incorporation and desorption are surface-temperature-dependent, while direct ion incorporation is independent of the surface temperature.

  6. Measurement of the ionization state and electron temperature of plasma during the ablation stage of a wire-array Z pinch using absorption spectroscopy.

    PubMed

    Ivanov, V V; Hakel, P; Mancini, R C; Chittenden, J P; Anderson, A; Durmaz, T; Wiewior, P; Papp, D; Altemara, S D; Astanovitskiy, A L; Chalyy, O

    2011-06-03

    Wire-array plasmas were investigated in the nonradiative ablation stage via x-ray absorption spectroscopy. A laser-produced Sm plasma was used to backlight Al wire arrays. The Sm spectrum was simultaneously observed by two spectrometers: one recorded the unattenuated spectrum and the other the transmission spectrum with 1.45-1.55 keV K-shell absorption lines. Analysis of absorption spectra revealed electron temperature in the range of 10-30 eV and the presence of F-, O-, N- and C-like Al ions in the absorbing plasma. A comparison of this electron temperature with the postprocessed absorption spectra of a 2D MHD simulation yields results in general agreement with the data analysis.

  7. Cyclic evolution of the electron temperature and density in dusty low-pressure radio frequency plasmas with pulsed injection of hexamethyldisiloxane

    SciTech Connect

    Garofano, V.; Stafford, L. E-mail: kremena.makasheva@laplace.univ-tlse.fr; Despax, B.; Clergereaux, R.; Makasheva, K. E-mail: kremena.makasheva@laplace.univ-tlse.fr

    2015-11-02

    Optical emission spectroscopy was used to analyze the very-low-frequency cyclic evolution of the electron energy and density caused by repetitive formation and loss of dust nanoparticles in argon plasmas with pulsed injection of hexamethyldisiloxane (HMDSO, [CH{sub 3}]{sub 6}Si{sub 2}O). After elaborating a Boltzmann diagram for Ar high-lying levels and a collisional-radiative model for Ar 2p (Paschen notation) states, temperatures characterizing the low- and high-energy parts of the electron population were calculated. Relative electron densities were also estimated from relative line emission intensities. Both temperatures increase when the dust occupation increases, and then decrease when dust is lost. The opposite trend was observed for the electron density. Such cyclic behaviors of the electron energy and electron density in the HMDSO-containing plasmas are in good agreement with the evolution processes in dusty plasmas, in which the formation of negative ions followed by an electron attachment on the surfaces of the nanoparticles is a critical phenomenon driving dust growth.

  8. Impact of temperature increments on tunneling barrier height and effective electron mass for plasma nitrided thin SiO{sub 2} layer on a large wafer area

    SciTech Connect

    Aygun, G.; Roeder, G.; Erlbacher, T.; Wolf, M.; Schellenberger, M.; Pfitzner, L.

    2010-10-15

    Thermally grown SiO{sub 2} layers were treated by a plasma nitridation process realized in a vertical furnace. The combination of a pulsed-low frequency plasma and a microwave remote plasma with N{sub 2}/NH{sub 3}/He feed gas mixture was used to nitride the thermally grown SiO{sub 2} gate dielectrics of MIS structures. Temperature dependency of effective masses and the barrier heights for electrons in pure thermally grown SiO{sub 2} as well as plasma nitrided SiO{sub 2} in high electric field by means of Fowler-Nordheim regime was determined. It is frequently seen from the literature that either effective electron mass or barrier height (generally effective electron mass) is assumed to be a constant and, as a result, the second parameter is calculated under the chosen assumption. However, in contrast to general attitude of previous studies, this work does not make any such assumptions for the calculation of neither of these two important parameters of an oxide at temperature ranges from 23 to 110 deg. C for SiO{sub 2}, and 23 to 130 deg. C for nitrided oxide. It is also shown here that both parameters are affected from the temperature changes; respectively, the barrier height decreases while the effective mass increases as a result of elevated temperature in both pure SiO{sub 2} and plasma nitrided SiO{sub 2}. Therefore, one parameter could be miscalculated if the other parameter, i.e., effective mass of electron, was assumed to be a constant with respect to variable physical conditions like changing temperature. Additionally, the barrier heights were calculated just by taking constant effective masses for both types of oxides to be able to compare our results to common literature values.

  9. Supersonic radiative transport of electron-hole plasma in semiconductors at room temperature studied by laser ultrasonics

    NASA Astrophysics Data System (ADS)

    Gao, W.; Gusev, V.; Glorieux, C.; Thoen, J.; Borghs, G.

    1997-02-01

    A piezoelectric semiconductor CdS 1- xSe x crystal under external electric loading was excited by pulsed nanosecond ultraviolet laser radiation. Acoustic waves were excited via the inverse piezoelectric effect due to the screening of the external electric field by expanding the space distribution of photogenerated electrons and holes. The duration of the interferometrically detected longitudinal acoustic pulses indicated that both the expansion of the screened region in space and the electron-hole plasma expansion are supersonic at the time scale of laser action. The value of 2 × 10 3 cm 2/s obtained for the electron-hole plasma diffusivity leads to the conclusion that the mechanism of this fast carrier transport is photon recycling, i.e. reabsorption of recombination radiation. This conclusion is also supported by the acoustic signals duration independence on magnitude and polarity of the external electric field.

  10. X-ray Spectropolarimetry of high temperature and high density plasma supported by LLNL Electron Beam Ion Trap Experiments

    SciTech Connect

    Shlyaptseva, A S; Kantsyrev, V L; Ouart, N D; Fedin, D A; Neill, P; Harris, C; Hamasha, S M; Hansen, S B; Safronova, U I; Beiersdorfer, P; Petrashen, A G

    2004-03-15

    Plasma polarization spectroscopy work done by our group since the 3rd US-Japan PPS Workshop is overviewed. Theoretically, the polarization dependence on various electron distribution functions for He-like, Ne-like, and Ni-like x-ray transitions for a wide range of Z has been investigated. In particular, this study was focused on the polarization dependence for monoenergetic and steep electron distribution functions. The diagnostically important spectral lines and features of K-, L-, and M-shell ions were identified which can be used in x-ray spectropolarimetry of plasma. Importance of polarization-sensitive LLNL Electron Beam Ion Trap data is emphasized. The results of the UNR polarization-sensitive Ti and Mo x-pinch experiments are discussed.

  11. Plasma flows in microscopic temperature filaments

    NASA Astrophysics Data System (ADS)

    Maggs, J. E.; Morales, G. J.

    2000-10-01

    We report on measurements of plasma flows in temperature filaments of radial size less than the electron skin depth. The temperature filaments are created by injecting a small electron beam at low voltages into a large magnetized plasma column in the LAPD plasma device at UCLA. The flows are measured using a small double sided Langmuir probe (or Mach probe). Three cases are investigated. The first case is a study of plasma flow under conditions of classical heat transport (A.T. Burke, J.E. Maggs, and G.J. Morales, Phys. Plasmas 7, 544 (2000)) (i.e., transport due to Coulomb collisions) and the transition to non-classical conditions (A.T. Burke, J.E. Maggs, and G.J. Morales, Phys. Plasmas 7, 1397 (2000)) in a temperature filament created in the afterglow plasma. The second case is a beam injected during the discharge plasma at voltages comparable to the plasma discharge voltage. In this case radially outward propagating temperature fluctuations are observed to emanate from the beam heated region. The third case is a beam injected in the edge region of the plasma during the discharge. Reductions in the axial transport of heat are observed apparently due to the large pre-existing fluctuations that naturally occur at the plasma edge.

  12. ECE imaging of electron temperature and electron temperature fluctuations (invited)

    SciTech Connect

    Deng, B. H.; Domier, C. W.; Luhmann, N. C.; Brower, D. L.; Cima, G.; Donne, A. J. H.; Oyevaar, T.; van de Pol, M. J.

    2001-01-01

    Electron cyclotron emission imaging (ECE imaging or ECEI) is a novel plasma diagnostic technique for the study of electron temperature profiles and fluctuations in magnetic fusion plasma devices. Instead of a single receiver located in the tokamak midplane as in conventional ECE radiometers, ECEI systems utilize large diameter imaging optics coupled with planar millimeter-wave imaging arrays to form multichannel ECE diagnostics with excellent spatial resolution. Combined with specially designed imaging optics, the use of these compact, low cost arrays has resulted in the excellent spatial resolution of the ECEI systems, the unique capability of two-dimensional measurements, and flexibility in the measurement of plasma fluctuations. Technical details and principles of this emerging diagnostic technique are described in this article. Illustrative experimental results are presented, together with a discussion of the further development of the diagnostic.

  13. On the E-H transition in inductively coupled radio frequency oxygen plasmas: I. Density and temperature of electrons, ground state and singlet metastable molecular oxygen

    NASA Astrophysics Data System (ADS)

    Wegner, Th; Küllig, C.; Meichsner, J.

    2017-02-01

    In this series of two papers, the E-H transition in a planar inductively coupled radio frequency discharge (13.56 MHz) in pure oxygen is studied using comprehensive plasma diagnostic methods. The electron density serves as the main plasma parameter to distinguish between the operation modes. The (effective) electron temperature, which is calculated from the electron energy distribution function and the difference between the floating and plasma potential, halves during the E-H transition. Furthermore, the pressure dependency of the RF sheath extension in the E-mode implies a collisional RF sheath for the considered total gas pressures. The gas temperature increases with the electron density during the E-H transition and doubles in the H-mode compared to the E-mode, whereas the molecular ground state density halves at the given total gas pressure. Moreover, the singlet molecular metastable density reaches 2% in the E-mode and 4% in the H-mode of the molecular ground state density. These measured plasma parameters can be used as input parameters for global rate equation calculations to analyze several elementary processes. Here, the ionization rate for the molecular oxygen ions is exemplarily determined and reveals, together with the optical excitation rate patterns, a change in electronegativity during the mode transition.

  14. Potential formation in a one-dimensional bounded plasma system containing a two-electron temperature plasma: Kinetic model and PIC simulation

    SciTech Connect

    Gyergyek, T.; Jurcic-Zlobec, B.; Cercek, M.

    2008-06-15

    Potential formation in a bounded plasma system that contains electrons with a two-temperature velocity distribution and is terminated by a floating, electron emitting electrode (collector) is studied by a one-dimensional kinetic model. A method on how to determine the boundary conditions at the collector for the numerical solution of the Poisson equation is presented. The difference between the regular and the irregular numerical solutions of the Poisson equation is explained. The regular numerical solution of the Poisson equation fulfills the boundary conditions at the source and can be computed for any distance from the collector. The irregular solution does not fulfill the source boundary conditions and the computation breaks down at some distance from the collector. An excellent agreement of the values of the potential at the inflection point found from the numerical solution of the Poisson equation with the values predicted by the analytical model is obtained. Potential, electric field, and particle density profiles found by the numerical solution of the Poisson equation are compared to the profiles obtained with the particle in cell computer simulation. A very good quantitative agreement of the potential and electric field profiles is obtained. For certain values of the parameters the analytical model predicts three possible values of the potential at the inflection point. In such cases always only one of the corresponding numerical solutions of the Poisson equation is regular, while the other two are irregular. The regular numerical solution of the Poisson equation always corresponds to the solution of the model that predicts the largest ion flux to the collector.

  15. High temperature electronics

    NASA Astrophysics Data System (ADS)

    Seng, Gary T.

    1991-03-01

    In recent years, the aerospace propulsion and space power communities have acknowledged a growing need for electronic devices that are capable of sustained high-temperature operation. Aeropropulsion applications for high-temperature electronic devices include engine ground test instrumentation such as multiplexers, analog-to-digital converters, and telemetry systems capable of withstanding hot section engine temperatures in excess of 600 C. Uncooled operation of control and condition monitoring systems in advanced supersonic aircraft would subject the electronics to temperatures in excess of 300 C. Similarly, engine-mounted integrated electronic sensors could reach temperatures which exceed 500 C. In addition to aeronautics, there are many other areas that could benefit from the existence of high-temperature electronic devices. Space applications include power electronic devices for space platforms and satellites. Since power electronics require radiators to shed waste heat, electronic devices that operate at higher temperatures would allow a reduction in radiator size. Terrestrial applications include deep-well drilling instrumentation, high power electronics, and nuclear reactor instrumentation and control. To meet the needs of the applications mentioned previously, the high-temperature electronics (HTE) program at the Lewis Research Center is developing silicon carbide (SiC) as a high-temperature semiconductor material. Research is focused on developing the crystal growth, growth modeling, characterization, and device fabrication technologies necessary to produce a family of SiC devices. Interest in SiC has grown dramatically in recent years due to solid advances in the technology. Much research remains to be performed, but SiC appears ready to emerge as a useful semiconductor material.

  16. Electron beam extraction on plasma cathode electron sources system

    NASA Astrophysics Data System (ADS)

    Purwadi, Agus; Taufik, M., Lely Susita R.; Suprapto, Saefurrochman, H., Anjar A.; Wibowo, Kurnia; Aziz, Ihwanul; Siswanto, Bambang

    2017-03-01

    ELECTRON BEAM EXTRACTION ON PLASMA CATHODE ELECTRON SOURCES SYSTEM. The electron beam extraction through window of Plasma Generator Chamber (PGC) for Pulsed Electron Irradiator (PEI) device and simulation of plasma potential has been studied. Plasma electron beam is extracted to acceleration region for enlarging their power by the external accelerating high voltage (Vext) and then it is passed foil window of the PEI for being irradiated to any target (atmospheric pressure). Electron beam extraction from plasma surface must be able to overcome potential barrier at the extraction window region which is shown by estimate simulation (Opera program) based on data of plasma surface potential of 150 V with Ueks values are varied by 150 kV, 175 kV and 200 kV respectively. PGC is made of 304 stainless steel with cylindrical shape in 30 cm of diameter, 90 cm length, electrons extraction window as many as 975 holes on the area of (15 × 65) cm2 with extraction hole cell in 0.3 mm of radius each other, an cylindrical shape IEP chamber is made of 304 stainless steel in 70 cm diameter and 30 cm length. The research result shown that the acquisition of electron beam extraction current depends on plasma parameters (electron density ne, temperature Te), accelerating high voltage Vext, the value of discharge parameter G, anode area Sa, electron extraction window area Se and extraction efficiency value α.

  17. Existence domains of arbitrary amplitude nonlinear structures in two-electron temperature space plasmas. II. High-frequency electron-acoustic solitons

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2012-12-15

    A three-component plasma model composed of ions, cool electrons, and hot electrons is adopted to investigate the existence of large amplitude electron-acoustic solitons not only for the model for which inertia and pressure are retained for all plasma species which are assumed to be adiabatic but also neglecting inertial effects of the hot electrons. Using the Sagdeev potential formalism, the Mach number ranges supporting the existence of large amplitude electron-acoustic solitons are presented. The limitations on the attainable amplitudes of electron-acoustic solitons having negative potentials are attributed to a number of different physical reasons, such as the number density of either the cool electrons or hot electrons ceases to be real valued beyond the upper Mach number limit, or, alternatively, a negative potential double layer occurs. Electron-acoustic solitons having positive potentials are found to be supported only if inertial effects of the hot electrons are retained and these are found to be limited only by positive potential double layers.

  18. Measurement of electron temperatures and electron energy distribution functions in dual frequency capacitively coupled CF{sub 4}/O{sub 2} plasmas using trace rare gases optical emission spectroscopy

    SciTech Connect

    Chen Zhiying; Donnelly, Vincent M.; Economou, Demetre J.; Chen, Lee; Funk, Merritt; Sundararajan, Radha

    2009-09-15

    Measurements of electron temperatures (T{sub e}) and electron energy distribution functions (EEDFs) in a dual frequency capacitively coupled etcher were performed by using trace rare gas optical emission spectroscopy (TRG-OES). The parallel plate etcher was powered by a high frequency (60 MHz) ''source'' top electrode and a low frequency (13.56 MHz) ''substrate'' bottom electrode. T{sub e} first increased with pressure up to {approx}20 mTorr and then decreased at higher pressures. Increasing the bottom rf power resulted in higher electron temperatures. Electron temperatures in 90% CF{sub 4}+10% O{sub 2} plasmas were similar to those in 80% CF{sub 4}+20% O{sub 2} plasmas. EEDF exhibited bi-Maxwellian characteristics with enhanced high energy tail, especially at pressures >20 mTorr.

  19. Spatially resolved measurements of ion density and electron temperature in a dual-frequency capacitively coupled plasma by complete floating double probe technique

    SciTech Connect

    Jiang Xiangzhan; Liu Yongxin; Yang Shuo; Lu Wenqi; Bi Zhenhua; Li Xiaosong; Wang Younian

    2011-01-15

    Spatially resolved measurements of the ion density and electron temperature in a dual-frequency capacitively coupled Ar discharge plasma are performed with a newly developed complete floating double probe. Axial and radial distributions of the ion density and electron temperature under various high-frequency (HF) power and gas pressure were studied in detail. Both the ion density and the electron temperature increased with increasing HF power. With increasing gas pressure from 1.3 to 9.3 Pa, the radial profile of ion density below the driven electrode experienced a change from ''bimodal'' to ''unimodal'' shape, with better uniformity being achieved at the optimal pressure of about 5 Pa. In addition, changing the axial profile of ion density was also observed with the peak shift toward the powered electrode at higher pressures. The measured results showed satisfying consistency with that of improved two dimensional fluid simulations.

  20. Nonlinear propagation of ion-acoustic waves in self-gravitating dusty plasma consisting of non-isothermal two-temperature electrons

    NASA Astrophysics Data System (ADS)

    Paul, S. N.; Chatterjee, A.; Paul, Indrani

    2017-01-01

    Nonlinear propagation of ion-acoustic waves in self-gravitating multicomponent dusty plasma consisting of positive ions, non-isothermal two-temperature electrons and negatively charged dust particles with fluctuating charges and drifting ions has been studied using the reductive perturbation method. It has been shown that nonlinear propagation of ion-acoustic waves in gravitating dusty plasma is described by an uncoupled third order partial differential equation which is a modified form of Korteweg-deVries equation, in contraries to the coupled nonlinear equations obtained by earlier authors. Quasi-soliton solution for the ion-acoustic solitary wave has been obtained from this uncoupled nonlinear equation. Effects of non-isothermal two-temperature electrons, gravity, dust charge fluctuation and drift motion of ions on the ion-acoustic solitary waves have been discussed.

  1. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Columnar growth of crystalline silicon films on aluminium-coated glass by inductively coupled plasma CVD at room temperature

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Xiao; Qin, Yan-Li; Yan, Heng-Qing; Gao, Ping-Qi; Li, Jun-Shuai; Yin, Min; He, De-Yan

    2009-02-01

    Silicon films were grown on aluminium-coated glass by inductively coupled plasma CVD at room temperature using a mixture of SiH4 and H2 as the source gas. The microstructure of the films was evaluated using Raman spectroscopy, scanning electron microscopy and atomic force microscopy. It was found that the films are composed of columnar grains and their surfaces show a random and uniform distribution of silicon nanocones. Such a microstructure is highly advantageous to the application of the films in solar cells and electron emission devices. Field electron emission measurement of the films demonstrated that the threshold field strength is as low as ~9.8 V/μm and the electron emission characteristic is reproducible. In addition, a mechanism is suggested for the columnar growth of crystalline silicon films on aluminium-coated glass at room temperature.

  2. Changes in core electron temperature fluctuations across the ohmic energy confinement transition in Alcator C-Mod plasmas

    NASA Astrophysics Data System (ADS)

    Sung, C.; White, A. E.; Howard, N. T.; Oi, C. Y.; Rice, J. E.; Gao, C.; Ennever, P.; Porkolab, M.; Parra, F.; Mikkelsen, D.; Ernst, D.; Walk, J.; Hughes, J. W.; Irby, J.; Kasten, C.; Hubbard, A. E.; Greenwald, M. J.; the Alcator C-Mod Team

    2013-08-01

    The first measurements of long wavelength (kyρs < 0.3) electron temperature fluctuations in Alcator C-Mod made with a new correlation electron cyclotron emission diagnostic support a long-standing hypothesis regarding the confinement transition from linear ohmic confinement (LOC) to saturated ohmic confinement (SOC). Electron temperature fluctuations decrease significantly (∼40%) crossing from LOC to SOC, consistent with a change from trapped electron mode (TEM) turbulence domination to ion temperature gradient (ITG) turbulence as the density is increased. Linear stability analysis performed with the GYRO code (Candy and Waltz 2003 J. Comput. Phys. 186 545) shows that TEMs are dominant for long wavelength turbulence in the LOC regime and ITG modes are dominant in the SOC regime at the radial location (ρ ∼ 0.8) where the changes in electron temperature fluctuations are measured. In contrast, deeper in the core (ρ < 0.8), linear stability analysis indicates that ITG modes remain dominant across the LOC/SOC transition. This radial variation suggests that the robust global changes in confinement of energy and momentum occurring across the LOC/SOC transition are correlated to local changes in the dominant turbulent mode near the edge.

  3. Measurements of Electron Temperature and Density Profiles of Plasmas Produced by Nike KrF Laser for Laser Plasma Instability (LPI) Research

    NASA Astrophysics Data System (ADS)

    Oh, Jaechul; Weaver, J. L.; Obenschain, S. P.; Schmitt, A. J.; Kehne, D. M.; Karasik, M.; Chan, L.-Y.; Serlin, V.; Phillips, L.

    2012-10-01

    ExperimentsfootnotetextJ. Oh, et al, GO5.4, APS DPP (2010).^,footnotetextJ. L. Weaver, et al, GO5.3, APS DPP (2010). using Nike KrF laser observed LPI signatures from CH plasmas at the laser intensities above ˜1x10^15 W/cm^2. Knowing spatial profiles of temperature (Te) and density (ne) in the underdense coronal region (0 < n < nc/4) of the plasma is essential to understanding the LPI observation. However, numerical simulation was the only way to access the profiles for the previous experiments. In the current Nike LPI experiment, a side-on grid imaging refractometer (GIR)footnotetextR. S. Craxton, et al, Phys. Fluids B 5, 4419 (1993). is being deployed for measuring the underdense plasma profiles. The GIR will resolve Te and ne in space taking a 2D snapshot of probe laser (λ= 263 nm, δt = 10 psec) beamlets (50μm spacing) refracted by the plasma at a selected time during the laser illumination. Time-resolved spectrometers with an absolute-intensity-calibrated photodiode array and a streak camera will simultaneously monitor light emission from the plasma in spectral ranges relevant to Raman (SRS) and two plasmon decay (TDP) instabilities. The experimental study of effects of the plasma profiles on the LPI initiation will be presented.

  4. Surface passivation of p-type Ge substrate with high-quality GeNx layer formed by electron-cyclotron-resonance plasma nitridation at low temperature

    NASA Astrophysics Data System (ADS)

    Fukuda, Yukio; Okamoto, Hiroshi; Iwasaki, Takuro; Otani, Yohei; Ono, Toshiro

    2011-09-01

    We have investigated the effects of the formation temperature and postmetallization annealing (PMA) on the interface properties of GeNx/p-Ge fabricated by the plasma nitridation of Ge substrates using an electron-cyclotron-resonance-generated nitrogen plasma. The nitridation temperature is found to be a critical parameter in improving the finally obtained GeNx/Ge interface properties. The GeNx/Ge formed at room temperature and treated by PMA at 400 °C exhibits the best interface properties with an interface trap density of 1 × 1011 cm-2 eV-1. The GeNx/Ge interface is unpinned and the Fermi level at the Ge surface can move from the valence band edge to the conduction band edge.

  5. Molecular dynamics simulations and generalized Lenard-Balescu calculations of electron-ion temperature relaxation in plasmas

    NASA Astrophysics Data System (ADS)

    Benedict, Lorin X.; Surh, Michael P.; Khairallah, Saad A.; Castor, John I.; Whitley, Heather D.; Richards, David F.; Glosli, James N.; Murillo, Michael S.; Graziani, Frank R.

    2011-10-01

    We present classical molecular dynamics (MD) calculations of temperature relaxation in hydrogen, Ar-doped hydrogen, and SF6 plasmas in which the two-particle interactions are represented by statistical potentials of the Dunn-Broyles and modified Kelbg forms. Using a multi-species generalized Lenard-Balescu theory in which the full frequency and wave-vector dependent dielectric response is included, we show that deviations of our hydrogen MD results from the weak-coupling theories such as Landau-Spitzer are due in large part to the use of the statistical potentials which approximate, in a classical way, the effects of quantum diffraction. Classical MD with Kelbg potentials is shown to be better at reproducing intermediate-to-weak-coupling results of true quantum-Coulomb plasmas, but it is also shown that MD with both types of statistical potential yield the correct quantum result in the limit of infinitesimal plasma coupling. Effects of dynamical screening in multi-component plasmas are also discussed.

  6. High-temperature plasma physics

    SciTech Connect

    Furth, H.P.

    1988-03-01

    Both magnetic and inertial confinement research are entering the plasma parameter range of fusion reactor interest. This paper reviews the individual and common technical problems of these two approaches to the generation of thermonuclear plasmas, and describes some related applications of high-temperature plasma physics.

  7. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    SciTech Connect

    Dawood, Mahmoud S.; Hamdan, Ahmad E-mail: Joelle.margot@umontreal.ca; Margot, Joëlle E-mail: Joelle.margot@umontreal.ca

    2015-11-15

    The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure) and compositions (argon, nitrogen and helium) on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  8. Numerical studies of independent control of electron density and gas temperature via nonlinear coupling in dual-frequency atmospheric pressure dielectric barrier discharge plasmas

    SciTech Connect

    Zhang, Z. L.; Nie, Q. Y. Wang, Z. B.; Gao, X. T.; Kong, F. R.; Sun, Y. F.; Jiang, B. H.

    2016-07-15

    Dielectric barrier discharges (DBDs) provide a promising technology of generating non-equilibrium cold plasmas in atmospheric pressure gases. For both application-focused and fundamental studies, it is important to explore the strategy and the mechanism for enabling effective independent tuning of key plasma parameters in a DBD system. In this paper, we report numerical studies of effects of dual-frequency excitation on atmospheric DBDs, and modulation as well as separate tuning mechanism, with emphasis on dual-frequency coupling to the key plasma parameters and discharge evolution. With an appropriately applied low frequency to the original high frequency, the numerical calculation demonstrates that a strong nonlinear coupling between two frequencies governs the process of ionization and energy deposition into plasma, and thus raises the electron density significantly (e.g., three times in this case) in comparisons with a single frequency driven DBD system. Nevertheless, the gas temperature, which is mainly determined by the high frequency discharge, barely changes. This method then enables a possible approach of controlling both averaged electron density and gas temperature independently.

  9. Recombinative plasma in electron runaway discharge

    SciTech Connect

    Kuznetsov, Yu.K.; Galvao, R.M.O.; Usuriaga, O.C.; Krasheninnikov, S.I.; Soboleva, T.K.; Tsypin, V.S.; Fonseca, A.M.M.; Ruchko, L.F.; Sanada, E.K.

    2005-07-15

    Cold recombinative plasma is the basic feature of the new regime of runaway discharges recently discovered in the Tokamak Chauffage Alfven Bresilien tokamak [R. M. O. Galvao et al., Plasma Phys. Controlled Fusion 43, 1181 (2001)]. With low plasma temperature, the resistive plasma current and primary Dreicer process of runaway generation are strongly suppressed at the stationary phase of the discharge. In this case, the runaway avalanche, which has been recently recognized as a novel important mechanism for runaway electron generation in large tokamaks, such as International Thermonuclear Experimental Reactor, during disruptions, and for electric breakdown in matter, is the only mechanism responsible for toroidal current generation and can be easily observed. The measurement of plasma temperature by the usual methods is a difficult task in fully runaway discharges. In the present work, various indirect evidences for low-temperature recombinative plasma are presented. The direct observation of recombinative plasma is obtained as plasma detachment from the limiter. The model of cold recombinative plasma is also supported by measurements of plasma density and H{sub {alpha}} emission radial profiles, analysis of time variations of these parameters due to the relaxation instability, estimations of plasma resistivity from voltage spikes, and energy and particle balance calculations.

  10. Effects of the parallel electron dynamics and finite ion temperature on the plasma blob propagation in the scrape-off layer

    SciTech Connect

    Jovanovic, D.; Shukla, P. K.; Pegoraro, F.

    2008-11-15

    A new three-dimensional model for the warm-ion turbulence at the tokamak edge plasma and in the scrape-off layer is proposed, and used to study the dynamics of plasma blobs in the scrape-off layer. The model is based on the nonlinear interchange mode, coupled with the nonlinear resistive drift mode, in the presence of the magnetic curvature drive, the density inhomogeneity, the electron dynamics along the open magnetic field lines, and the electron-ion and electron-neutral collisions. Within the present model, the effect of the sheath resistivity decreases with the distance from the wall, resulting in the bending and the break up of the plasma blob structure. Numerical solutions exhibit the coupling of interchange modes with nonlinear drift modes, causing the collapse of the blob in the lateral direction, followed by a clockwise rotation and radial propagation. The symmetry breaking, caused both by the parallel resistivity and the finite ion temperature, introduces a poloidal component in the plasma blob propagation, while the overall stability properties and the speed are not affected qualitatively.

  11. Electron temperature differences and double layers

    NASA Technical Reports Server (NTRS)

    Chan, C.; Hershkowitz, N.; Lonngren, K. E.

    1983-01-01

    Electron temperature differences across plasma double layers are studied experimentally. It is shown that the temperature differences across a double layer can be varied and are not a result of thermalization of the bump-on-tail distribution. The implications of these results for electron thermal energy transport in laser-pellet and tandem-mirror experiments are also discussed.

  12. Electron Scattering in Hot/Warm Plasmas

    SciTech Connect

    Rozsnyai, B F

    2008-01-18

    Electrical and thermal conductivities are presented for aluminum, iron and copper plasmas at various temperatures, and for gold between 15000 and 30000 Kelvin. The calculations are based on the continuum wave functions computed in the potential of the temperature and density dependent self-consistent 'average atom' (AA) model of the plasma. The cross sections are calculated by using the phase shifts of the continuum electron wave functions and also in the Born approximation. We show the combined effect of the thermal and radiative transport on the effective Rosseland mean opacities at temperatures from 1 to 1000 eV. Comparisons with low temperature experimental data are also presented.

  13. Electron Cooling in a Magnetically Expanding Plasma.

    PubMed

    Little, J M; Choueiri, E Y

    2016-11-25

    Electron cooling in a magnetically expanding plasma, which is a fundamental process for plasma flow and detachment in magnetic nozzles, is experimentally investigated using a radio frequency plasma source and magnetic nozzle (MN). Probe measurements of the plasma density, potential, and electron temperature along the center line of the MN indicate that the expansion follows a polytropic law with exponent γ_{e}=1.15±0.03. This value contradicts isothermal electron expansion, γ_{e}=1, which is commonly assumed in MN models. The axial variation of the measured quantities can be described by a simple quasi-1D fluid model with classical electron thermal conduction, for which it has been previously shown that a value of γ_{e}≈1.19 is expected in the weakly collisional limit. A new criterion, derived from the model, ensures efficient ion acceleration when a critical value for the ratio of convected to conducted power is exceeded.

  14. Effect of dust charge fluctuations on dust acoustic structures in magnetized dusty plasma containing nonextensive electrons and two-temperature isothermal ions

    SciTech Connect

    Araghi, F.; Dorranian, D.

    2016-02-15

    Effect of dust electrical charge fluctuations on the nature of dust acoustic solitary waves (DASWs) in a four-species magnetized dusty plasma containing nonextensive electrons and two-temperature isothermal ions has been investigated. In this model, the negative dust electric charge is considered to be proportional to the plasma space potential. The nonlinear Zakharov–Kuznetsov (ZK) and modified Zakharov–Kuznetsov (mZK) equations are derived for DASWs by using the standard reductive perturbation method. The combined effects of electron nonextensivity and dust charge fluctuations on the DASW profile are analyzed. The different ranges of the nonextensive q-parameter are considered. The results show that solitary waves the amplitude and width of which depend sensitively on the nonextensive q-parameter can exist. Due to the electron nonextensivity and dust charge fluctuation rate, our dusty plasma model can admit both positive and negative potential solitons. The results show that the amplitude of the soliton increases with increasing electron nonextensivity, but its width decreases. Increasing the electrical charge fluctuations leads to a decrease in both the amplitude and width of DASWs.

  15. Runaway electrons in a fully and partially ionized nonideal plasma

    SciTech Connect

    Ramazanov, T.S.; Turekhanova, K.M.

    2005-10-01

    This paper reports on a study of electron runaway for a nonideal plasma in an external electric field. Based on pseudopotential models of nonideal fully and partially ionized plasmas, the friction force was derived as a function of electron velocities. Dependences of the electron free path on plasma density and nonideality parameters were obtained. The impact of the relative number of runaway electrons on their velocity and temperature was considered for classical and semiclassical models of a nonideal plasma. It has been shown that for the defined intervals of the coupled plasma parameter, the difference between the relative numbers of runaway electron values is essential for various plasma models.

  16. Determination of the electron temperature by optical emission spectroscopy in a 13.56 MHz dusty methane plasma: Influence of the power

    SciTech Connect

    Massereau-Guilbaud, Veronique; Geraud-Grenier, Isabelle; Plain, Andre

    2009-12-01

    Optical emission spectroscopy is applied to the study of a radiofrequency (13.56 MHz) discharge in methane used to obtain hydrogenated carbon films and particles. The methane dissociation allows the creation of species in the plasma bulk as H{sub 2}, H, and CH. The emission lines of these species are studied as a function of time and of incident rf power. The electron temperature is determined from the two line radiance ratio method and the corona balance model using the Balmer lines (H{sub alpha}, H{sub beta}, and H{sub gamma}). The incident rf power enhancement in the range 40-120 W leads to the increase in the emission line intensities as the electron temperature decreases. The temporal variations of CH and hydrogen emission lines, of the dc self-bias voltage, and of the electron temperature are correlated both with the particle behavior and growth in the plasma, and with the coating that grows onto the powered electrode.

  17. Higher order nonlinear equations for the dust-acoustic waves in a dusty plasma with two temperature-ions and nonextensive electrons

    SciTech Connect

    Emamuddin, M.; Yasmin, S.; Mamun, A. A.

    2013-04-15

    The nonlinear propagation of dust-acoustic waves in a dusty plasma whose constituents are negatively charged dust, Maxwellian ions with two distinct temperatures, and electrons following q-nonextensive distribution, is investigated by deriving a number of nonlinear equations, namely, the Korteweg-de-Vries (K-dV), the modified Korteweg-de-Vries (mK-dV), and the Gardner equations. The basic characteristics of the hump (positive potential) and dip (negative potential) shaped dust-acoustic (DA) Gardner solitons are found to exist beyond the K-dV limit. The effects of two temperature ions and electron nonextensivity on the basic features of DA K-dV, mK-dV, and Gardner solitons are also examined. It has been observed that the DA Gardner solitons exhibit negative (positive) solitons for qq{sub c}) (where q{sub c} is the critical value of the nonextensive parameter q). The implications of our results in understanding the localized nonlinear electrostatic perturbations existing in stellar polytropes, quark-gluon plasma, protoneutron stars, etc. (where ions with different temperatures and nonextensive electrons exist) are also briefly addressed.

  18. High-temperature electronics

    NASA Technical Reports Server (NTRS)

    Matus, Lawrence G.; Seng, Gary T.

    1990-01-01

    To meet the needs of the aerospace propulsion and space power communities, the high temperature electronics program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. This program supports a major element of the Center's mission - to perform basic and developmental research aimed at improving aerospace propulsion systems. Research is focused on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of SiC devices.

  19. Electron Boltzmann equation in nonthermal plasmas

    NASA Technical Reports Server (NTRS)

    Kunc, J. A.; Soon, W. H.

    1991-01-01

    Numerical and analytical solutions of the electron Boltzmann equation for a two-temperature steady-state He plasma are examined in a broad range of conditions, i.e., atom temperature ranging from 5000 K to 20,000 K; electron temperature ranging from 10,000 K to 20,000 K; and atom density ranging from 10 to the 10th to 10 to the 18th per cu cm. The WKB analytical solution is shown to be satisfactory in most situations. Attention is also given to the deviation of the electron distribution from Maxwellian, and to the possibility of raising the tail of the distribution.

  20. Fast temperature relaxation model in dense plasmas

    NASA Astrophysics Data System (ADS)

    Faussurier, Gérald; Blancard, Christophe

    2017-01-01

    We present a fast model to calculate the temperature-relaxation rates in dense plasmas. The electron-ion interaction-potential is calculated by combining a Yukawa approach and a finite-temperature Thomas-Fermi model. We include the internal energy as well as the excess energy of ions using the QEOS model. Comparisons with molecular dynamics simulations and calculations based on an average-atom model are presented. This approach allows the study of the temperature relaxation in a two-temperature electron-ion system in warm and hot dense matter.

  1. A study of density in electron-cyclotron-resonance plasma

    SciTech Connect

    Uhm, H.S.; Lee, P.H.; Kim, Y.I.; Kim, J.H.; Chang, H.Y.

    1995-08-01

    A theory is developed for the density profile of low-temperature plasmas confined by applied magnetic field and an experiment of the electron-cyclotron-resonance (ECR) plasma is conducted to compare the theoretical prediction and experimental measurements. Due to a large electron mobility along the magnetic field, electrons move quickly out of the system, leaving ions behind and building a space charge potential, which leads to the ambipolar diffusion of ions. In a steady-state condition, the plasma generation by ionization of neutral molecules is in balance with plasma loss due to the diffusion, leading to the electron temperature equation, which is expressed in terms of the plasma size, chamber pressure, and the ionization energy and cross section of neutrals. The power balance condition leads to the plasma density equation, which is also expressed in terms of the electron temperature, the input microwave power and the chamber pressure. It is shown that the plasma density increases, reaches its peak and decreases, as the chamber pressure increases from a small value (0.1 mTorr). These simple expressions of electron temperature and density provide a scaling law of ECR plasma in terms of system parameters. After carrying out an experimental observation, it is concluded that the theoretical predictions of the electron temperature and plasma density agree remarkably well with experimental data. A large-volume plasma generated by the electron-cyclotron-resonance (ECR) mechanism plays a pivotal role in the plasma processing, including thin-film depositions and plasma etching technologies.

  2. Implementation of a multichannel soft x-ray diagnostic for electron temperature measurements in TJ-II high-density plasmas

    SciTech Connect

    Baiao, D.; Varandas, C.; Molinero, A.; Chercoles, J.

    2012-10-15

    Based on the multi-foil technique, a multichannel soft x-ray diagnostic for electron temperature measurements has been recently implemented in the TJ-II stellarator. The diagnostic system is composed by four photodiodes arrays with beryllium filters of different thickness. An in-vacuum amplifier board is coupled to each array, aiming at preventing induced noise currents. The Thomson scattering and the vacuum ultraviolet survey diagnostics are used for assessing plasma profiles and composition, being the analysis carried out with the radiation code IONEQ. The electron temperature is determined through the different signal-pair ratios with temporal and spatial resolution. The design and preliminary results from the diagnostic are presented.

  3. Central electron temperature estimations of TJ-II neutral beam injection heated plasmas based on the soft x ray multi-foil technique

    SciTech Connect

    Baiao, D.; Varandas, C.

    2012-05-15

    The core electron temperature (T{sub e0}) of neutral beam heated plasmas is determined in TJ-II stellarator by using soft x ray detectors with beryllium filters of different thickness, based on the method known as the foil absorption technique. T{sub e0} estimations are done with the impurity code IONEQ, making use of complementary information from the TJ-II soft x ray tomography and the VUV survey diagnostics. When considering the actual electron density and temperature profile shapes, an acceptable agreement is found with Thomson scattering measurements for 8 different magnetic configurations. The impact of the use of both neutral beam injectors on the T{sub e0} measurements is addressed. Also, the behaviour of T{sub e0} during spontaneous profile transitions is presented.

  4. Measurements of Laser Plasma Instability (LPI) and Electron Density/Temperature Profiles in Plasmas Produced by the Nike KrF Laser

    NASA Astrophysics Data System (ADS)

    Oh, Jaechul; Weaver, J. L.; Serlin, V.; Obenschain, S. P.

    2016-10-01

    We will present results of simultaneous measurements of LPI-driven light scattering and density/temperature profiles in CH plasmas produced by the Nike krypton fluoride laser (λ = 248 nm). The primary diagnostics for the LPI measurement are time-resolved spectrometers with absolute intensity calibration in spectral ranges relevant to the optical detection of stimulated Raman scattering or two plasmon decay. The spectrometers are capable of monitoring signal intensity relative to thermal background radiation from plasma providing a useful way to analyze LPI initiation. For further understanding of LPI processes, the recently implemented grid image refractometer (Nike-GIR)a is used to measure the coronal plasma profiles. In this experiment, Nike-GIR is equipped with a 5th harmonic probe laser (λ = 213 nm) in attempt to probe into a high density region over the previous peak density with λ = 263 nm probe light ( 4 ×1021 cm-3). The LPI behaviors will be discussed with the measured data sets. Work supported by DoE/NNSA.

  5. Search for Correlation Between Plasma Rotation and Electron Temperature Gradient Scale Length in LOC/SOC Transition at Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Houshmandyar, Saeid; Rowan, William L.; Phillips, Perry E.; Walk, John R.; Rice, John E.

    2015-11-01

    Understanding the mechanism governing the linear ohmic confinement (LOC) and the transition to saturated ohmic confinement (SOC) has long been a focus of tokamak research. It is commonly accepted that at low density, the confinement is dominated by electron-scale turbulence while at high density, the turbulence is dominated by ion temperature gradient. At Alcator C-Mod, the core rotation reversal was shown to be consistent with this ansatz. However a recent study at AUG suggests that the intrinsic rotation behavior is rather determined by local plasma parameters regardless of the heating method or the confinement regime. Here, we follow this idea and search for dependence of intrinsic rotation on electron temperature gradient scale length, a quantity with a pivotal role in plasma transport. The high-resolution (1 μs, 7mm) electron cyclotron emission diagnostic at C-Mod (FRCECE) coupled with the BT jog technique allows direct LTe measurements. In the BT jog technique, a 1.5% change in the toroidal magnetic field shifts the viewing volume of the ECE by ~ 1 cm, and the ratio of the average of the signal to the change in the signal during its ramp-up yields LTe. Supported by USDoE awards DE-FG03-96ER-54373 and DE-FC02-99ER54512.

  6. Development of a spectroscopic technique for simultaneous magnetic field, electron density, and temperature measurements in ICF-relevant plasmas (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dutra, Eric C.; Covington, Aaron M.; Darling, Timothy; Mancini, Roberto C.; Haque, Showera; Angermeier, William A.

    2016-09-01

    Visible spectroscopic techniques are often used in plasma experiments to measure B-field induced Zeeman splitting, electron densities via Stark broadening and temperatures from Doppler broadening. However, when electron densities and temperatures are sufficiently high, the broadening of the Stark and Doppler components can dominate the emission spectra and obscure the Zeeman component. In this research, we are developing a time-resolved multi-axial technique for measuring the Zeeman, Stark, and Doppler broadened line emission of dense magnetized plasmas for Z-pinch and Dense Plasma Focus (DPF) accelerators. The line emission is used to calculate the electron densities, temperatures, and B-fields. In parallel, we are developing a line-shape modeling code that incorporates the broadening effects due to Stark, Doppler, and Zeeman effects for dense magnetized plasma. Experiments conducted at the University of Nevada (Reno) at the Nevada Terawatt Facility (NTF) using the 1 MA Z-pinch (Zebra). The research explored the response of Al III doublet, 4p 2P3/2 to 4s 2S1/2 and 4p 2P1/2 to 4s 2S1/2 transitions. Optical light emitted from the pinch is fiber coupled to high-resolution spectrometers. The dual spectrometers are coupled to two high-speed visible streak cameras to capture time-resolved emission spectra from the experiment. The data reflects emission spectra from 100 ns before the current peak to 100 ns after the current peak, where the current peak is approximately the time at which the pinch occurs. The Al III doublet is used to measure Zeeman, Stark, and Doppler broadened emission. The line emission is then used to calculate the temperature, electron density, and B-fields. The measured quantities are used as initial parameters for the line shape code to simulate emission spectra and compare to experimental results. Future tests are planned to evaluate technique and modeling on other material wire array, gas puff, and DPF platforms. This work was done by National

  7. Energy spectra of plasma sheet ions and electrons from about 50 eV/e to about 1 MeV during plamsa temperature transitions

    NASA Technical Reports Server (NTRS)

    Christon, S. P.; Mitchell, D. G.; Williams, D. J.; Frank, L. A.; Huang, C. Y.; Eastman, T. E.

    1988-01-01

    ISEE-1 charged-particle measurements obtained during eight plasma temperature transitions (PTTs) in 1978-1979 are compiled in tables and graphs and analyzed in detail, comparing the ion and electron differential energy spectra with the predictions of theoretical models. PTTs are defined as approximately 1-h periods of low bulk plasma velocity and steadily increasing or decreasing thermal energy. A Maxwellian distribution is found to be inadequate in describing the PTT energy spectra, but velocity-exponential and kappa distributions are both successful, the latter especially at higher energies. The power-law index kappa varies from PTT to PTT, but the high-energy spectral index and overall shape of the distribution remain constant during a PTT; both spatial and temporal effects are observed.

  8. Energy spectra of plasma sheet ions and electrons from about 50 eV/e to about 1 MeV during plamsa temperature transitions

    NASA Technical Reports Server (NTRS)

    Christon, S. P.; Mitchell, D. G.; Williams, D. J.; Frank, L. A.; Huang, C. Y.; Eastman, T. E.

    1988-01-01

    ISEE-1 charged-particle measurements obtained during eight plasma temperature transitions (PTTs) in 1978-1979 are compiled in tables and graphs and analyzed in detail, comparing the ion and electron differential energy spectra with the predictions of theoretical models. PTTs are defined as approximately 1-h periods of low bulk plasma velocity and steadily increasing or decreasing thermal energy. A Maxwellian distribution is found to be inadequate in describing the PTT energy spectra, but velocity-exponential and kappa distributions are both successful, the latter especially at higher energies. The power-law index kappa varies from PTT to PTT, but the high-energy spectral index and overall shape of the distribution remain constant during a PTT; both spatial and temporal effects are observed.

  9. Electron temperature probe

    NASA Astrophysics Data System (ADS)

    Oyama, K.-I.; Cheng, C. Z.

    2013-11-01

    The electron temperature probe (ETP) was invented in Japan in 1970's. The probe measures the electron temperature accurately and the measurement is not influenced by the electrode contamination. The instrument has low weight, low data transmission bit rate and low power consumption. The probe has been deployed in many sounding rockets, Earth orbiting scientific satellites, and Mars exploration spacecraft in Japan. The probe has also been deployed in sounding rockets in West Germany, India, Canada, USA, and Brazil. The probe has also been deployed in Brazilian satellites, Korean satellites, and recently as a Taiwan satellite payload. The manuscript describes the principle of the ETP instrument, the system configuration, the mechanical interface with respect to the sensor location, the control timing between data processing units; some useful information, the interference with other instruments, and future improvements and tasks. Some useful information for conducting performance check after the instrument fabrication and before the flight deployment is also presented in Appendix A.

  10. Electron kinetics in capacitively coupled plasmas modulated by electron injection

    NASA Astrophysics Data System (ADS)

    Zhang, Ya; Peng, Yanli; Innocenti, Maria Elena; Jiang, Wei; Wang, Hong-yu; Lapenta, Giovanni

    2017-09-01

    The controlling effect of an electron injection on the electron energy distribution function (EEDF) and on the energetic electron flux, in a capacitive radio-frequency argon plasma, is studied using a one-dimensional particle-in-cell/Monte Carlo collisions model. The input power of the electron beam is as small as several tens of Watts with laboratory achievable emission currents and energies. With the electron injection, the electron temperature decreases but with a significant high energy tail. The electron density, electron temperature in the sheath, and electron heating rate increase with the increasing emission energy. This is attributed to the extra heating of the energetic electrons in the EEDF tail. The non-equilibrium EEDF is obtained for strong non-local distributions of the electric field, electron heating rate, excitation, and ionization rate, indicating the discharge has transited from a volume heating (α-mode dominated) into a sheath heating (γ-mode dominated) type. In addition, the electron injection not only modifies the self-bias voltage, but also enhances the electron flux that can reach the electrodes. Moreover, the relative population of energetic electrons significantly increases with the electron injection compared to that without the electron injection, relevant for modifying the gas and surface chemistry reactions.

  11. Electron cyclotron resonance plasma photosa)

    NASA Astrophysics Data System (ADS)

    Rácz, R.; Biri, S.; Pálinkás, J.

    2010-02-01

    In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, gas composition, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas.

  12. Electron cyclotron resonance plasma photos.

    PubMed

    Rácz, R; Biri, S; Pálinkás, J

    2010-02-01

    In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, gas composition, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas.

  13. Electron cyclotron resonance plasma photos

    SciTech Connect

    Racz, R.; Palinkas, J.; Biri, S.

    2010-02-15

    In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, gas composition, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas.

  14. Electron Bernstein Wave Emission from RFP Plasmas

    NASA Astrophysics Data System (ADS)

    Nornberg, M. D.; Thomas, M.; Anderson, J.; Forest, C. B.

    1998-11-01

    Electron cyclotron emission (ECE) has proven to be a powerfull diagnostic tool in tokamak plasmas for determining the time evolution of the electron temperature profile. The standard technique of observing O-mode or X-mode electromagnetic waves normal to the magnetic field is not applicable to reversed field pinch (RFP) plasmas since the plasma frequency is much larger than the electron cyclotron frequency. We are investigating the use of electron Bernstein waves (presumed to be in thermal equilibrium with the electrons) through the O-X-B mode conversion process. At oblique incidence, the evanescent layer separating the plamsa cutoff from the cyclotron cutoff vanishes, allowing conversion of the Bernstein mode waves to the extraordinary mode and finally to the ordinary mode. The O-mode radiation is received by a phased array antenna consisting of two waveguides on the edge of the plasma, and the spectrum of emitted radiation is measured using a radiometer spanning 4-8 GHz. In addition to providing information about the electron temperature profile, the spectrum can provide a novel method of measuring the central magnetic field strength for current profile reconstructions.

  15. Particle Transport in Pure Electron Plasmas.

    NASA Astrophysics Data System (ADS)

    Kriesel, J. M.; Driscoll, C. F.

    1998-10-01

    At UCSD we confine pure-electron plasmas in Penning-Malmberg traps, which consist of cylindrical electrodes in an axial magnetic field (B ~ 100G). The trap is under ultra-high vacuum (10-10 Torr) so that transport due to electron-neutral collisions is negligible. Instead, cross-field particle transport is due to electron-electron collsions or from interactions with external fields. A plasma in one of our traps is roughly cylindrical in shape and rotates about its own axis due to the E x B drift from the space-charge field. Electron-electron collisions bring the plasma to a thermal equilibrium state of rigid rotation and uniform temperature. We find that the transport is driven by shears in the rotation velocity, and measure a coefficient of viscosity which is as much as 10,000 times larger than classical theory. This transport is driven by long-range ``E × B drift Coulomb collisions'' with impact parameters on the order of a Debye length rather than a cyclotron radius, as in classical theory. In our plasmas λD >> r_c, and O'Neil and Dubin have developed theories(Daniel H.E. Dubin, Phys. Plasmas 5), 1688 (1998) of transport in this regime. In addition to this work, I will also present measurements on the transport due to externally applied fields. The scalings provide insight into the overall confinement properties of our traps.

  16. Nonlinear dust-ion acoustic periodic travelling waves in a magnetized plasma with two temperature superthermal electrons and stationary charged dust grains

    NASA Astrophysics Data System (ADS)

    Abdelwahed, H. G.; El-Shewy, E. K.; El-Depsy, A.; EL-Shamy, E. F.

    2017-02-01

    In this research, the nonlinear propagation of dust-ion acoustic (DIA) periodic travelling waves in a dusty plasma consisting of cold ions, stationary charged dust grains, and two temperature superthermal electrons is theoretically studied. A nonlinear Zakharov-Kuznetsov equation, which describes nonlinear dust-ion acoustic waves, is derived using a reductive perturbation method. Furthermore, the bifurcation theory has been employed to study the nonlinear propagation of DIA periodic travelling wave solutions. In the proposed model, the co-existence of both compressive and rarefactive DIA periodic travelling waves are found. The numerical investigations illustrate that the characteristics of nonlinear DIA periodic travelling waves strongly depend on the temperature ratio, both the concentration and the superthermality of cold electrons, the ion cyclotron frequency, the direction cosines of wave vector k along z axis, and the concentration of dusty grains. The present investigation can help in better understanding of nonlinear DIA periodic travelling waves in astrophysical environments with two temperature superthermal electrons such as Saturn's magnetosphere.

  17. Low temperature plasma sintering of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Ma, Siyuan; Bromberg, Vadim; Liu, Liang; Egitto, Frank D.; Chiarot, Paul R.; Singler, Timothy J.

    2014-02-01

    The fabrication of flexible electronics using the deposition of solution-processed nanomaterials generally requires low-temperature post-processing to optimize functionality. We studied sintering of silver nanoparticle (AgNP) films on glass substrates by applying argon (Ar) plasma to achieve improved electrical conductivity. This process meets the low temperature processing requirements for standard low-cost polymeric flexible substrates. The relationship between plasma parameters (such as power and sintering time) versus sintering results (such as electrical sheet resistance, sintered structure depth, materials composition variation, and film nanostructure) is reported for 23 and 77 nm diameter AgNPs. In addition, plasma processing typically induces a small surface thermal effect. We monitored the surface temperatures of the AgNP films in-situ during plasma sintering. By sintering control groups at these monitored surface temperatures using a vacuum oven, we confirmed that the resistivity due to plasma sintering is less than that produced by thermal sintering. Our data show that, the measured lowest resistivities for plasma sintered AgNP films are about only 5 and 12 times greater than the bulk Ag resistivity for 23 and 77 nm, respectively.

  18. CONFINEMENT OF HIGH TEMPERATURE PLASMA

    DOEpatents

    Koenig, H.R.

    1963-05-01

    The confinement of a high temperature plasma in a stellarator in which the magnetic confinement has tended to shift the plasma from the center of the curved, U-shaped end loops is described. Magnetic means are provided for counteracting this tendency of the plasma to be shifted away from the center of the end loops, and in one embodiment this magnetic means is a longitudinally extending magnetic field such as is provided by two sets of parallel conductors bent to follow the U-shaped curvature of the end loops and energized oppositely on the inside and outside of this curvature. (AEC)

  19. Temperature Relaxation in Non-Ideal Plasmas

    NASA Astrophysics Data System (ADS)

    Gericke, Dirk O.; Murillo, Michael S.

    2001-10-01

    The equilibration process of multi-temperature plasmas, i.e., the energy transfer between electrons and ions, is investigated for the case of hot electrons and cold ions. Such non-equilibrium plasmas occur in various experiments, including the creation and heating of plasmas with short-pulse lasers and intense ion beams. Temperature separation occurs since these drivers couple almost entirely to the electrons. The standard approach to the equilibration rates goes back to the early works of Landau and Spitzer. However, this approach is only valid for systems where the Coulomb logarithm is larger than three, which clearly fails for strongly coupled plasmas. We first generalize this approach by considering hyperbolic orbits for the particle trajectories. Then we calculate the energy transfer rates using a quantal kinetic equation of the Boltzmann type which allows an exact (T-matrix) treatment of close collisions. On this basis, we demonstrate the importance of hyperbolic orbits, quantum defraction effects on the scattering cross section, a correct treatment of the distribution, dynamic screening effects, and the influence of the plasma composition.

  20. TG wave autoresonant control of plasma temperature

    SciTech Connect

    Kabantsev, A. A. Driscoll, C. F.

    2015-06-29

    The thermal correction term in the Trivelpiece-Gould (TG) wave’s frequency has been used to accurately control the temperature of electron plasma, by applying a swept-frequency continuous drive autoresonantly locked in balance with the cyclotron cooling. The electron temperature can be either “pegged” at a desired value (by constant drive frequency); or varied cyclically (following the tailored frequency course), with rates limited by the cooling time (on the way down) and by chosen drive amplitude (on the way up)

  1. A search for the Sunyaev-Zel'dovich effect at millimeter wavelengths. [cosmic background photon energy increase due to Compton scattering by high temperature galactic cluster plasma electrons

    NASA Technical Reports Server (NTRS)

    Meyer, S. S.; Jeffries, A. D.; Weiss, R.

    1983-01-01

    It is believed that X-ray emission from clusters of galaxies represents thermal bremsstrahlung from a hot plasma. According to Sunyaev and Zel'dovich (1972), the plasma column density and temperature derived from this model imply a measurable distortion of the cosmic background radiation (CBR) in the cluster direction. This distortion results from the Compton scattering of the CBR photons by the electrons in the plasma, resulting in an average increase of each photon. This process, known as the Sunyaev-Zel'dovich effect, is photon conserving and 'shifts' the CBR spectrum to higher frequencies. The result is a decrease of flux at frequencies below 7.5 per cm (the Rayleigh-Jeans region), and an increase above. The investigation is concerned with measurements of the Sunyaev-Zel'dovich effect at frequencies in the range from 3 to 10 per cm. Attention is given to the employed observing and analysis technique, and an initial null result for the cluster Abell 1795.

  2. 30-cm electron cyclotron plasma generator

    NASA Technical Reports Server (NTRS)

    Goede, Hank

    1987-01-01

    Experimental results on the development of a 30-cm-diam electron cyclotron resonance plasma generator are presented. This plasma source utilizes samarium-cobalt magnets and microwave power at a frequency of 4.9 GHz to produce a uniform plasma with densities of up to 3 x 10 to the 11th/cu cm in a continuous fashion. The plasma generator contains no internal structures, and is thus inherently simple in construction and operation and inherently durable. The generator was operated with two different magnetic geometries. One used the rare-earth magnets arranged in an axial line cusp configuration, which directly showed plasma production taking place near the walls of the generator where the electron temperature was highest but with the plasma density peaking in the central low B-field regions. The second configuration had magnets arranged to form azimuthal line cusps with approximately closed electron drift surfaces; this configuration showed an improved electrical efficiency of about 135 eV/ion.

  3. Characterization of electron cyclotron resonance hydrogen plasmas

    SciTech Connect

    Outten, C.A. . Dept. of Nuclear Engineering); Barbour, J.C.; Wampler, W.R. )

    1990-01-01

    Electron cyclotron resonance (ECR) plasmas yield low energy and high ion density plasmas. The characteristics downstream of an ECR hydrogen plasma were investigated as a function of microwave power and magnetic field. A fast-injection Langmuir probe and a carbon resistance probe were used to determine plasma potential (V{sub p}), electron density (N{sub e}), electron temperature (T{sub e}), ion energy (T{sub i}), and ion fluence. Langmuir probe results showed that at 17 cm downstream from the ECR chamber the plasma characteristics are approximately constant across the center 7 cm of the plasma for 50 Watts of absorbed power. These results gave V{sub p} = 30 {plus minus} 5 eV, N{sub e} = 1 {times} 10{sup 8} cm{sup {minus}3}, and T{sub e} = 10--13 eV. In good agreement with the Langmuir probe results, carbon resistance probes have shown that T{sub i} {le} 50 eV. Also, based on hydrogen chemical sputtering of carbon, the hydrogen (ion and energetic neutrals) fluence rate was determined to be 1 {times} 10{sup 16}/cm{sup 2}-sec. at a pressure of 1 {times} 10{sup {minus}4} Torr and for 50 Watts of absorbed power. 19 refs.

  4. On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex-stabilized nitrogen plasma jet.

    PubMed

    Prevosto, L; Kelly, H; Mancinelli, B R

    2014-05-01

    Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N2 gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10,900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 10(22) m(-3) were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches operated at power levels of about 15 kW.

  5. On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    SciTech Connect

    Prevosto, L. Mancinelli, B. R.; Kelly, H.

    2014-05-15

    Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N{sub 2} gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10 900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 10{sup 22} m{sup −3} were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches operated at power levels of about 15 kW.

  6. On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    NASA Astrophysics Data System (ADS)

    Prevosto, L.; Kelly, H.; Mancinelli, B. R.

    2014-05-01

    Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N2 gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10 900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 1022 m-3 were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches operated at power levels of about 15 kW.

  7. Existence domains of arbitrary amplitude nonlinear structures in two-electron temperature space plasmas. I. Low-frequency ion-acoustic solitons

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2012-07-15

    Using the Sagdeev pseudopotential technique, the existence of large amplitude ion-acoustic solitons is investigated for a plasma composed of ions, and hot and cool electrons. Not only are all species treated as adiabatic fluids but the model for which inertial effects of the hot electrons is neglected whilst retaining inertia and pressure for the ions and cool electrons has also been considered. The focus of this investigation has been on identifying the admissible Mach number ranges for large amplitude nonlinear ion-acoustic soliton structures. The lower Mach number limit yields a minimum velocity for the existence of ion-acoustic solitons. The upper Mach number limit for positive potential solitons is found to coincide with the limiting value of the potential (positive) beyond which the ion number density ceases to be real valued, and ion-acoustic solitons can no longer exist. Small amplitude solitons having negative potentials are found to be supported when the temperature of the cool electrons is negligible.

  8. Non-Maxwellian electron energy distribution function in He, He/Ar, He/Xe/H2 and He/Xe/D2 low temperature afterglow plasma

    NASA Astrophysics Data System (ADS)

    Plasil, R.; Korolov, I.; Kotrik, T.; Dohnal, P.; Bano, G.; Donko, Z.; Glosik, J.

    2009-08-01

    Experimental studies of the electron energy distribution function “EEDF” under well defined conditions in flowing afterglow plasma, using a Langmuir probe are reported. The EEDF is measured in He2 + and Ar+ dominated plasmas and in XeH+ and XeD+ dominated recombining plasmas. He is used as a buffer gas at medium pressures in all experiments (1600 Pa, 250 K). The deviation of the measured EEDF from Maxwellian distribution is shown to depend on plasma composition and on the processes governing the plasma decay. The influence of energetic electrons produced during the plasma decay on the body and tail of the EEDF is observed. The mechanism of energy balance in afterglow plasma is discussed.

  9. A simple electron plasma wave

    NASA Astrophysics Data System (ADS)

    Brodin, G.; Stenflo, L.

    2017-03-01

    Considering a class of solutions where the density perturbations are functions of time, but not of space, we derive a new exact large amplitude wave solution for a cold uniform electron plasma. This result illustrates that most simple analytical solutions can appear even if the density perturbations are large.

  10. Characteristic temperatures of hypervelocity dust impact plasmas

    NASA Astrophysics Data System (ADS)

    Collette, A.; Malaspina, D. M.; Sternovsky, Z.

    2016-09-01

    The effective ion and electron temperatures of dust impact generated plasma clouds are measured experimentally as a function of impact speed in the range of 4-20 km/s. The measurements are performed in an experimental setup that resembles the detection of dust particles by electric field or plasma wave antennas on spacecraft. The spacecraft is modeled as a conductive plate and a cylindrical antenna connected to voltage follower electronics is used to measure the collected charge. The setup is bombarded with dust particles using the University of Colorado IMPACT dust accelerator facility. The effective ion and electron temperatures are determined from the variation of the impact signals with an applied bias voltage. The results show that the temperatures of the electrons remain at around or below 5 eV over the investigated impact speed range. The characteristic ion temperature is about 5 eV at 4 km/s; however, it increases with increasing impact speed to > 10 eV at 20 km/s. Given that the floating potentials of spacecraft and antennas are on the order of a few volts, the findings suggest that any model for the interpretation of dust impact signals should take into account the effects of a finite temperatures.

  11. Spectroscopic diagnostics of high temperature plasmas

    SciTech Connect

    Moos, W.

    1990-01-01

    A three-year research program for the development of novel XUV spectroscopic diagnostics for magnetically confined fusion plasmas is proposed. The new diagnostic system will use layered synthetic microstructures (LSM) coated, flat and curved surfaces as dispersive elements in spectrometers and narrow band XUV filter arrays. In the framework of the proposed program we will develop impurity monitors for poloidal and toroidal resolved measurements on PBX-M and Alcator C-Mod, imaging XUV spectrometers for electron density and temperature fluctuation measurements in the hot plasma core in TEXT or other similar tokamaks and plasma imaging devices in soft x-ray light for impurity behavior studies during RF heating on Phaedrus T and carbon pellet ablation in Alcator C-Mod. Recent results related to use of multilayer in XUV plasma spectroscopy are presented. We also discuss the latest results reviewed to q{sub o} and local poloidal field measurements using Zeeman polarimetry.

  12. Effective field theory for plasmas at all temperatures and densities

    NASA Astrophysics Data System (ADS)

    Braaten, Eric

    1993-05-01

    The solution of the plasmon problem and the subsequent development of an effective field-theory approach to ultrarelativistic plasmas are reviewed. The effective Lagrangians that summarize collective effects in ultrarelativistic quark-gluon and electron-photon plasmas are presented. A generalization that describes an electromagnetic plasma at all temperatures and densities is proposed.

  13. Three-dimensional model of electron beam generated plasma

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid; Balakrishna, Ajit; Agarwal, Ankur; Dorf, Leonid; Collins, Kenneth; Boris, David R.; Walton, Scott G.

    2017-06-01

    A three-dimensional model for magnetized electron beam generated plasma is described, which includes a coupled fluid simulation of the bulk plasma and a Monte Carlo model for beam electrons. A modified form of the classical expressions for magnetized-plasma electron transport coefficients is used in the fluid plasma model. The plasma model is calibrated and validated using Langmuir probe measurements in a cylindrical electron beam generated plasma, where the beam is launched parallel to the magnetic field. The electron density (n e ) and temperature (T e ) are measured along and across the beam for several gas pressures and magnetic fields in Ar. The validated plasma model is then used to examine a three-dimensional electron beam generated plasma system. Generally, plasma densities are on the order of 1016 m-3 and, since there is no externally applied electric field in the plasma region, T e is below 1.25 eV in Ar. The chamber in the simulation is slightly asymmetric perpendicular to the axis of the electron beam and the magnetic field. This asymmetry combined with the E × B drift produce non-uniformities in the plasma even if the magnetic field is spatially uniform in the chamber. However, the cross-field plasma uniformity can be controlled by tailoring the magnetic field profile to enhance or reduce plasma production near the periphery of the chamber.

  14. Confinement Studies in High Temperature Spheromak Plasmas

    SciTech Connect

    Hill, D N; Mclean, H S; Wood, R D; Casper, T A; Cohen, B I; Hooper, E B; LoDestro, L L; Pearlstein, L D; Romero-Talamas, C

    2006-10-23

    Recent results from the SSPX spheromak experiment demonstrate the potential for obtaining good energy confinement (Te > 350eV and radial electron thermal diffusivity comparable to tokamak L-mode values) in a completely self-organized toroidal plasma. A strong decrease in thermal conductivity with temperature is observed and at the highest temperatures, transport is well below that expected from the Rechester-Rosenbluth model. Addition of a new capacitor bank has produced 60% higher magnetic fields and almost tripled the pulse length to 11ms. For plasmas with T{sub e} > 300eV, it becomes feasible to use modest (1.8MW) neutral beam injection (NBI) heating to significantly change the power balance in the core plasma, making it an effective tool for improving transport analysis. We are now developing detailed designs for adding NBI to SSPX and have developed a new module for the CORSICA transport code to compute the correct fast-ion orbits in SSPX so that we can simulate the effect of adding NBI; initial results predict that such heating can raise the electron temperature and total plasma pressure in the core by a factor of two.

  15. Electron density measurements for plasma adaptive optics

    NASA Astrophysics Data System (ADS)

    Neiswander, Brian W.

    Over the past 40 years, there has been growing interest in both laser communications and directed energy weapons that operate from moving aircraft. As a laser beam propagates from an aircraft in flight, it passes through boundary layers, turbulence, and shear layers in the near-region of the aircraft. These fluid instabilities cause strong density gradients which adversely affect the transmission of laser energy to a target. Adaptive optics provides corrective measures for this problem but current technology cannot respond quickly enough to be useful for high speed flight conditions. This research investigated the use of plasma as a medium for adaptive optics for aero-optics applications. When a laser beam passes through plasma, its phase is shifted proportionally to the electron density and gas heating within the plasma. As a result, plasma can be utilized as a dynamically controllable optical medium. Experiments were carried out using a cylindrical dielectric barrier discharge plasma chamber which generated a sub-atmospheric pressure, low-temperature plasma. An electrostatic model of this design was developed and revealed an important design constraint relating to the geometry of the chamber. Optical diagnostic techniques were used to characterize the plasma discharge. Single-wavelength interferometric experiments were performed and demonstrated up to 1.5 microns of optical path difference (OPD) in a 633 nm laser beam. Dual-wavelength interferometry was used to obtain time-resolved profiles of the plasma electron density and gas heating inside the plasma chamber. Furthermore, a new multi-wavelength infrared diagnostic technique was developed and proof-of-concept simulations were conducted to demonstrate the system's capabilities.

  16. Radiative electron capture in nonequilibrium plasmas

    SciTech Connect

    Milchberg, H.M.; Weisheit, J.C.

    1982-01-19

    Formulae have been obtained for the degree of linear polarization of recombination radiation from a homogeneous plasma having an anisotropic electron velocity distribution, f(v vector), characterized by an axis of symmetry. Polarization measurements are described which utilize these formulae to determine aspects of the anisotropy such as the symmetry axis direction and the lowest order even angular moments of f(v vector). As a special case, if the plasma conforms to a distribution such as a bi-Maxwellian with drift, one can determine the quantities u/sub D//T/sub parallel to/ and (1/T/sub parallel to/ - 1/T/sub perpendicular to/) which involve the electron drift speed, and the perpendicular and parallel electron temperatures. Also, the radiative recombination rate has been calculated for ions whose speeds are comparable to or greater than the electron thermal speed. The change in the rate is small for thermonuclear products in fusion plasmas, but large for cosmic rays in interstellar plasma.

  17. Temperature dependent evolution of the local electronic structure of atmospheric plasma treated carbon nanotubes: Near edge x-ray absorption fine structure study

    SciTech Connect

    Roy, S. S.; Papakonstantinou, P.; Okpalugo, T. I. T.; Murphy, H.

    2006-09-01

    Near edge x-ray absorption fine structure (NEXAFS) spectroscopy has been employed to obtain the temperature dependent evolution of the electronic structure of acid treated carbon nanotubes, which were further modified by dielectric barrier discharge plasma processing in an ammonia atmosphere. The NEXAFS studies were performed from room temperature up to 900 deg. C. The presence of oxygen and nitrogen containing functional groups was observed in C K edge, N K edge, and O K edge NEXAFS spectra of the multiwalled carbon nanotubes. The N K edge spectra revealed three types of {pi}* features, the source of which was decisively identified by their temperature dependent evolution. It was established that these features are attributed to pyridinelike, NO, and graphitelike structures, respectively. The O K edge indicated that both carbonyl (C=O), {pi}*(CO), and ether C-O-C, {sigma}*(CO), functionalities were present. Upon heating in a vacuum to 900 deg. C the {pi}*(CO) resonances disappeared while the {sigma}*(CO) resonances were still present confirming their higher thermal stability. Heating did not produce a significant change in the {pi}* feature of the C K edge spectrum indicating that the tabular structure of the nanotubes is essentially preserved following the thermal decomposition of the functional groups on the nanotube surface.

  18. Determination of electron temperature and density at plasma edge in the Large Helical Device with opacity-incorporated helium collisional-radiative model

    NASA Astrophysics Data System (ADS)

    Goto, M.; Sawada, K.

    2014-04-01

    Spectra of neutral helium in the visible wavelength range are measured for a discharge in the Large Helical Device (LHD). The electron temperature (Te) and density (ne) are derived from the intensity distribution of helium emission lines. For that purpose, a collisional-radiative model developed by Sawada et al. [Plasma and Fusion Res. 2010;5:001] which takes the reabsorption effect into account is used. It is found that incorporation of the reabsorption effect is necessary to obtain a set of Te and ne giving consistent line intensity distribution with the measurement, and that those parameters obtained vary as the line-averaged ne changes in the course of time. The position where the helium line emission dominantly takes place is located with the help of Te and ne profiles measured by the Thomson scattering system. The result indicates that the emission position is almost fixed at the place where the connection length of the magnetic field lines to the divertor plate leaps beyond 10 m. Because intense neutral atom line emission suggests the vigorous ionization of neutral atoms, the helium line emission location determined here can be regarded as the effective boundary of the plasma.

  19. Dense simple plasmas as high-temperature liquid simple metals

    NASA Technical Reports Server (NTRS)

    Perrot, F.

    1990-01-01

    The thermodynamic properties of dense plasmas considered as high-temperature liquid metals are studied. An attempt is made to show that the neutral pseudoatom picture of liquid simple metals may be extended for describing plasmas in ranges of densities and temperatures where their electronic structure remains 'simple'. The primary features of the model when applied to plasmas include the temperature-dependent self-consistent calculation of the electron charge density and the determination of a density and temperature-dependent ionization state.

  20. Plasma response to electron energy filter in large volume plasma device

    SciTech Connect

    Sanyasi, A. K.; Awasthi, L. M.; Mattoo, S. K.; Srivastava, P. K.; Singh, S. K.; Singh, R.; Kaw, P. K.

    2013-12-15

    An electron energy filter (EEF) is embedded in the Large Volume Plasma Device plasma for carrying out studies on excitation of plasma turbulence by a gradient in electron temperature (ETG) described in the paper of Mattoo et al. [S. K. Mattoo et al., Phys. Rev. Lett. 108, 255007 (2012)]. In this paper, we report results on the response of the plasma to the EEF. It is shown that inhomogeneity in the magnetic field of the EEF switches on several physical phenomena resulting in plasma regions with different characteristics, including a plasma region free from energetic electrons, suitable for the study of ETG turbulence. Specifically, we report that localized structures of plasma density, potential, electron temperature, and plasma turbulence are excited in the EEF plasma. It is shown that structures of electron temperature and potential are created due to energy dependence of the electron transport in the filter region. On the other hand, although structure of plasma density has origin in the particle transport but two distinct steps of the density structure emerge from dominance of collisionality in the source-EEF region and of the Bohm diffusion in the EEF-target region. It is argued and experimental evidence is provided for existence of drift like flute Rayleigh-Taylor in the EEF plasma.

  1. Temperature relaxation in a magnetized plasma

    SciTech Connect

    Dong, Chao; Ren, Haijun; Cai, Huishan; Li, Ding

    2013-10-15

    A magnetic field greatly affects the relaxation phenomena in a plasma when the particles’ thermal gyro-radii are smaller than the Debye length. Its influence on the temperature relaxation (TR) is investigated through consideration of binary collisions between charged particles in the presence of a uniform magnetic field within a perturbation theory. The relaxation times are calculated. It is shown that the electron-electron (e-e) and ion-ion (i-i) TR rates first increase and then decrease as the magnetic field grows, and the doubly logarithmic term contained in the electron-ion (e-i) TR rate results from the exchange between the electron parallel and the ion perpendicular kinetic energies.

  2. Whistler Solitons in Plasma with Anisotropic Hot Electron Admixture

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Krivorutsky, E. N.; Gallagher, D. L.

    1999-01-01

    The longitudinal and transverse modulation instability of whistler waves in plasma, with a small admixture of hot anisotropic electrons, is discussed. If the hot particles temperature anisotropy is positive, it is found that, in such plasma, longitudinal perturbations can lead to soliton formation for frequencies forbidden in cold plasma. The soliton is enriched by hot particles. The frequency region unstable to transverse modulation in cold plasma in the presence of hot electrons is divided by stable domains. For both cases the role of hot electrons is more significant for whistlers with smaller frequencies.

  3. Energy efficiency of electron plasma emitters

    SciTech Connect

    Zalesski, V. G.

    2011-12-15

    Electron emission influence from gas-discharge plasma on plasma emitter energy parameters is considered. It is shown, that electron emission from plasma is accompanied by energy contribution redistribution in the gas-discharge from plasma emitter supplies sources-the gas-discharge power supply and the accelerating voltage power supply. Some modes of electron emission as a result can be realized: 'a probe measurements mode,' 'a transitive mode,' and 'a full switching mode.'.

  4. Self-absorption Effects In Experimental Methods Used To Determine Electron Density And Gas Temperature In An Argon Microwave Plasma (SWP) Generated At Atmospheric Pressure

    SciTech Connect

    Santiago, I.; Munoz, J.; Calzada, M. D.

    2008-10-22

    In this work a procedure was applied to verify that self-absorption does not affect the spectral lines used in the experimental determination of the electron density and the gas temperature in surface wave discharges at atmospheric pressure. Therefore, the values of electron density and gas temperature obtained are not perturbed by this phenomenon.

  5. Pioneer Venus Orbiter Electron Temperature Probe

    NASA Technical Reports Server (NTRS)

    Krehbiel, J. P.; Brace, L. H.; Theis, R. F.; Cutler, J. R.; Pinkus, W. H.; Kaplan, R. B.

    1980-01-01

    The Orbiter Electron Temperature Probe (OETP) instrumentation and measurement technique has been designed to perform in-situ measurements of electron temperature and electron and ion density in the ionosphere of Venus. Adaptive sweep voltage circuitry continuously tracks the changing electron temperature and spacecraft potential while auto-ranging electrometers adjust their gain in response to the changing plasma density. Control signals used in the instrument to achieve this automatic tracking provide a continuous monitor of the ionospheric parameters without telemetering each volt-ampere curve. Internal data storage permits high data rate sampling of selected raw characteristic curves for low rate transmission to earth. These curves are used to verify or correct the inflight processed data. Sample in orbit measurements are presented to demonstrate instrument performance.

  6. Temperature peaking at beginning of breakdown in 2.45 GHz pulsed off-resonance electron cyclotron resonance ion source hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Cortázar, O. D.; Megía-Macías, A.; Vizcaíno-de-Julián, A.

    2012-10-01

    An experimental study of temperature and density evolution during breakdown in off-resonance ECR hydrogen plasma is presented. Under square 2.45 GHz microwave excitation pulses with a frequency of 50 Hz and relative high microwave power, unexpected transient temperature peaks that reach 18 eV during 20 μs are reported at very beginning of plasma breakdown. Decays of such peaks reach final stable temperatures of 5 eV at flat top microwave excitation pulse. Evidence of interplay between incoming power and duty cycle giving different kind of plasma parameters evolutions engaged to microwave coupling times is observed. Under relative high power conditions where short microwave coupling times are recorded, high temperature peaks are measured. However, for lower incoming powers and longer coupling times, temperature evolves gradually to a higher final temperature without peaking. On the other hand, the early instant where temperature peaks are observed also suggest a possible connection with preglow processes during breakdown in ECRIS plasmas.

  7. Temperature peaking at beginning of breakdown in 2.45 GHz pulsed off-resonance electron cyclotron resonance ion source hydrogen plasma

    SciTech Connect

    Cortazar, O. D.

    2012-10-15

    An experimental study of temperature and density evolution during breakdown in off-resonance ECR hydrogen plasma is presented. Under square 2.45 GHz microwave excitation pulses with a frequency of 50 Hz and relative high microwave power, unexpected transient temperature peaks that reach 18 eV during 20 {mu}s are reported at very beginning of plasma breakdown. Decays of such peaks reach final stable temperatures of 5 eV at flat top microwave excitation pulse. Evidence of interplay between incoming power and duty cycle giving different kind of plasma parameters evolutions engaged to microwave coupling times is observed. Under relative high power conditions where short microwave coupling times are recorded, high temperature peaks are measured. However, for lower incoming powers and longer coupling times, temperature evolves gradually to a higher final temperature without peaking. On the other hand, the early instant where temperature peaks are observed also suggest a possible connection with preglow processes during breakdown in ECRIS plasmas.

  8. Temperature peaking at beginning of breakdown in 2.45 GHz pulsed off-resonance electron cyclotron resonance ion source hydrogen plasma.

    PubMed

    Cortázar, O D; Megía-Macías, A; Vizcaíno-de-Julián, A

    2012-10-01

    An experimental study of temperature and density evolution during breakdown in off-resonance ECR hydrogen plasma is presented. Under square 2.45 GHz microwave excitation pulses with a frequency of 50 Hz and relative high microwave power, unexpected transient temperature peaks that reach 18 eV during 20 μs are reported at very beginning of plasma breakdown. Decays of such peaks reach final stable temperatures of 5 eV at flat top microwave excitation pulse. Evidence of interplay between incoming power and duty cycle giving different kind of plasma parameters evolutions engaged to microwave coupling times is observed. Under relative high power conditions where short microwave coupling times are recorded, high temperature peaks are measured. However, for lower incoming powers and longer coupling times, temperature evolves gradually to a higher final temperature without peaking. On the other hand, the early instant where temperature peaks are observed also suggest a possible connection with preglow processes during breakdown in ECRIS plasmas.

  9. Revisiting plasma hysteresis with an electronically compensated Langmuir probe

    NASA Astrophysics Data System (ADS)

    Srivastava, P. K.; Singh, S. K.; Awasthi, L. M.; Mattoo, S. K.

    2012-09-01

    The measurement of electron temperature in plasma by Langmuir probes, using ramped bias voltage, is seriously affected by the capacitive current of capacitance of the cable between the probe tip and data acquisition system. In earlier works a dummy cable was used to balance the capacitive currents. Under these conditions, the measured capacitive current was kept less than a few mA. Such probes are suitable for measurements in plasma where measured ion saturation current is of the order of hundreds of mA. This paper reports that controlled balancing of capacitive current can be minimized to less than 20 μA, allowing plasma measurements to be done with ion saturation current of the order of hundreds of μA. The electron temperature measurement made by using probe compensation technique becomes independent of sweep frequency. A correction of ≤45% is observed in measured electron temperature values when compared with uncompensated probe. This also enhances accuracy in the measurement of fluctuation in electron temperature as δTpk-pk changes by ˜30%. The developed technique with swept rate ≤100 kHz is found accurate enough to measure both the electron temperature and its fluctuating counterpart. This shows its usefulness in measuring accurately the temperature fluctuations because of electron temperature gradient in large volume plasma device plasma with frequency ordering ≤50 kHz.

  10. Revisiting plasma hysteresis with an electronically compensated Langmuir probe.

    PubMed

    Srivastava, P K; Singh, S K; Awasthi, L M; Mattoo, S K

    2012-09-01

    The measurement of electron temperature in plasma by Langmuir probes, using ramped bias voltage, is seriously affected by the capacitive current of capacitance of the cable between the probe tip and data acquisition system. In earlier works a dummy cable was used to balance the capacitive currents. Under these conditions, the measured capacitive current was kept less than a few mA. Such probes are suitable for measurements in plasma where measured ion saturation current is of the order of hundreds of mA. This paper reports that controlled balancing of capacitive current can be minimized to less than 20 μA, allowing plasma measurements to be done with ion saturation current of the order of hundreds of μA. The electron temperature measurement made by using probe compensation technique becomes independent of sweep frequency. A correction of ≤45% is observed in measured electron temperature values when compared with uncompensated probe. This also enhances accuracy in the measurement of fluctuation in electron temperature as δT(pk-pk) changes by ~30%. The developed technique with swept rate ≤100 kHz is found accurate enough to measure both the electron temperature and its fluctuating counterpart. This shows its usefulness in measuring accurately the temperature fluctuations because of electron temperature gradient in large volume plasma device plasma with frequency ordering ≤50 kHz.

  11. Finite temperature static charge screening in quantum plasmas

    NASA Astrophysics Data System (ADS)

    Eliasson, B.; Akbari-Moghanjoughi, M.

    2016-07-01

    The shielding potential around a test charge is calculated, using the linearized quantum hydrodynamic formulation with the statistical pressure and Bohm potential derived from finite temperature kinetic theory, and the temperature effects on the force between ions is assessed. The derived screening potential covers the full range of electron degeneracy in the equation of state of the plasma electrons. An attractive force between shielded ions in an arbitrary degenerate plasma exists below a critical temperature and density. The effect of the temperature on the screening potential profile qualitatively describes the ion-ion bound interaction strength and length variations. This may be used to investigate physical properties of plasmas and in molecular-dynamics simulations of fermion plasma. It is further shown that the Bohm potential including the kinetic corrections has a profound effect on the Thomson scattering cross section in quantum plasmas with arbitrary degeneracy.

  12. Electronics Temperature Control,

    DTIC Science & Technology

    1975-01-01

    called the Seebeck potential or voltage. The Thomson effect occurs when a conductor is subjected to a thermal gradient. In such a conductor electrons...they add to their thermal energy state by absorption of heat. The Thomson effect is described-by the 38 _____IA Thomson coefficient,"C, by let where

  13. On temperature bifurcation of beryllium and lithium plasma facing components

    SciTech Connect

    Smirnov, R. D.; Krasheninnikov, S. I.; Pigarov, A. Yu.

    2009-12-15

    The mechanism of temperature bifurcation of plasma contacting surfaces due to recycling of the ionized surface material vapor is considered. It is shown that this mechanism can lead to overheating of beryllium and lithium plasma facing components (in particular, in fusion devices) prior to the thermionic electron emission mechanism. The surface temperatures and the plasma parameters, at which the considered mechanism triggers the local overheating of beryllium and lithium components, are evaluated. The increase in the surface heat load due to secondary electron emission is also considered. It is shown that the combined effects of energy and impact angle distributions of the plasma electrons can increase the averaged secondary electron emission yield to values higher than unity and can lower the average electron energy, at which such yields are achieved.

  14. Radiation temperature of non-equilibrium plasmas

    SciTech Connect

    Arunasalam, V.

    1991-07-01

    In fusion devices measurements of the radiation temperature T{sub r} ({omega}, k) near the electron cyclotron frequency {omega}{sub C} and the second harmonic 2{omega}{sub C} in directions nearly perpendicular to the confining magnetic field B (i.e., k {approx} k {perpendicular}) serve to map out the electron temperature profiles T{sub e}(r,t). For optically thick plasma at thermodynamic equilibrium T{sub r} = T{sub e}. However, there is increasing experimental evidence for the presence of non-equilibrium electron distributions (such as a drifting Maxwellian with appreciable values of the streaming parameter {omicron} = v{sub d}/v{sub t}, a bi- Maxwellian, and anisotropic Maxwellian with T {perpendicular} {ne} T {parallel}, etc.,) in tokamak plasmas, especially in the presence of radio-frequency heating. Here, we examine (both non-relativistically and relativistically) the dependence of T{sub r} on {omicron}, T{perpendicular}/T{parallel}, T{sub h}/T{sub b}, n{sub h}/n{sub b}etc., where n{sub b}, n{sub h}, T{sub b}, T{sub h} are the densities and temperatures, respectively, of the bulk and the hot components of the bi-Maxwellian plasma. Our bi-Maxwellian results predict that the ratio T{sub r}/T{sub e} is a very sensitive function of the ratios n{sub h}/n{sub b} and T{sub h}/T{sub b}. Further, these relativistic and non-relativistic results satisfy the well-known limit c {yields} {infinity} correspondence principle'', showing that the intensity of the emission and absorption line is independent of the line broadening mechanism. 44 refs., 2 figs.

  15. Solitary and shock waves in magnetized electron-positron plasma

    SciTech Connect

    Lu, Ding; Li, Zi-Liang; Abdukerim, Nuriman; Xie, Bai-Song

    2014-02-15

    An Ohm's law for electron-positron (EP) plasma is obtained. In the framework of EP magnetohydrodynamics, we investigate nonrelativistic nonlinear waves' solutions in a magnetized EP plasma. In the collisionless limit, quasistationary propagating solitary wave structures for the magnetic field and the plasma density are obtained. It is found that the wave amplitude increases with the Mach number and the Alfvén speed. However, the dependence on the plasma temperature is just the opposite. Moreover, for a cold EP plasma, the existence range of the solitary waves depends only on the Alfvén speed. For a hot EP plasma, the existence range depends on the Alfvén speed as well as the plasma temperature. In the presence of collision, the electromagnetic fields and the plasma density can appear as oscillatory shock structures because of the dissipation caused by the collisions. As the collision frequency increases, the oscillatory shock structure becomes more and more monotonic.

  16. Level shifts and inelastic electron scattering in dense plasmas

    NASA Technical Reports Server (NTRS)

    Davis, J.; Blaha, M.

    1982-01-01

    A completely quantum mechanical formalism has been developed to describe the high density plasma effects on fundamental atomic parameters. Both the bound and free electrons are treated by a method which in principle is similar to Hartree's self-consistent field method. The free plasma electrons' wavefunction is obtained from the Schroedinger equation with the effective potential representing the spherically averaged Coulomb interaction with bound and free electrons. Results are given for level shifts, coefficients of transition probabilities, and electron collision cross sections of Ne(9+) for temperatures of 200 and 500 eV for an electron density range of 1-6 x 10 to the 24th per cu cm.

  17. Electron density and electron temperature measurement in a bi-Maxwellian electron distribution using a derivative method of Langmuir probes

    SciTech Connect

    Choi, Ikjin; Chung, ChinWook; Youn Moon, Se

    2013-08-15

    In plasma diagnostics with a single Langmuir probe, the electron temperature T{sub e} is usually obtained from the slope of the logarithm of the electron current or from the electron energy probability functions of current (I)-voltage (V) curve. Recently, Chen [F. F. Chen, Phys. Plasmas 8, 3029 (2001)] suggested a derivative analysis method to obtain T{sub e} by the ratio between the probe current and the derivative of the probe current at a plasma potential where the ion current becomes zero. Based on this method, electron temperatures and electron densities were measured and compared with those from the electron energy distribution function (EEDF) measurement in Maxwellian and bi-Maxwellian electron distribution conditions. In a bi-Maxwellian electron distribution, we found the electron temperature T{sub e} obtained from the method is always lower than the effective temperatures T{sub eff} derived from EEDFs. The theoretical analysis for this is presented.

  18. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    USDA-ARS?s Scientific Manuscript database

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic upd...

  19. Time and space resolved measurement of the electron temperature, mass density and ionization state in the ablation plasma between two exploding Al wiresa)

    NASA Astrophysics Data System (ADS)

    Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Hansen, S. B.

    2012-05-01

    We have determined the properties of plasma around and between two exploding wires using high-resolution x-ray absorption spectroscopy. Plasma densities and temperatures ranging from ≳0.1g/cm3 and a few eV to less than 0.01 g/cm3 and 30 eV have been measured in experiments at Cornell University with two 40 μm aluminum (Al) wires spaced 1 mm apart driven by ˜150 kA peak current pulses with 100 ns rise time. The wire plasma was backlit by the 1.4-1.6 keV continuum radiation produced by a Mo wire X-pinch. The spectrometer employed two spherically bent quartz crystals to record the absorption and backlighter spectra simultaneously. The transition between the dense Al wire core and the coronal plasma is seen as a transition from cold K-edge absorption to Mg-, Na-, and finally Ne-like absorption at the boundary. In the plasma that accumulates between the wires, ionization states up to C-Like Al are observed. The spectrometer geometry and ˜2μm X-pinch source size provide 0.3 eV spectral resolution and 20 μm spatial resolution enabling us to see 1s → 2p satellite transitions as separate lines as well as O-, F-, and Ne-like 1s → 3p transitions that have not been seen before. A step wedge was used to calibrate the transmission, enabling density to be measured within a factor of two and temperature to be measured within ±25%. A genetic algorithm was developed to fit synthetic spectra calculated using the collisional-radiative code SCRAM to the experimental spectra. In order to obtain agreement it was necessary to assume multiple plasma regions with variable thicknesses, thereby allowing the inferred plasma conditions to vary along the absorption path.

  20. Measurements of laser-induced plasma temperature field in deep penetration laser welding

    NASA Astrophysics Data System (ADS)

    Chen, Genyu; Zhang, Mingjun; Zhao, Zhi; Zhang, Yi; Li, Shichun

    2013-02-01

    Laser-induced plasma in deep penetration laser welding is located inside or outside the keyhole, namely, keyhole plasma or plasma plume, respectively. The emergence of laser-induced plasma in laser welding reveals important information of the welding technological process. Generally, electron temperature and electron density are two important characteristic parameters of plasma. In this paper, spectroscopic measurements of electron temperature and electron density of the keyhole plasma and plasma plume in deep penetration laser welding conditions were carried out. To receive spectra from several points separately and simultaneously, an Optical Multi-channel Analyser (OMA) was developed. On the assumption that the plasma was in local thermal equilibrium, the temperature was calculated with the spectral relative intensity method. The spectra collected were processed with Abel inversion method to obtain the temperature fields of keyhole plasma and plasma plume.

  1. Plasma lenses for focusing relativistic electron beams

    SciTech Connect

    Govil, R.; Wheeler, S.; Leemans, W.

    1997-04-01

    The next generation of colliders require tightly focused beams with high luminosity. To focus charged particle beams for such applications, a plasma focusing scheme has been proposed. Plasma lenses can be overdense (plasma density, n{sub p} much greater than electron beam density, n{sub b}) or underdense (n{sub p} less than 2 n{sub b}). In overdense lenses the space-charge force of the electron beam is canceled by the plasma and the remaining magnetic force causes the electron beam to self-pinch. The focusing gradient is nonlinear, resulting in spherical aberrations. In underdense lenses, the self-forces of the electron beam cancel, allowing the plasma ions to focus the beam. Although for a given beam density, a uniform underdense lens produces smaller focusing gradients than an overdense lens, it produces better beam quality since the focusing is done by plasma ions. The underdense lens can be improved by tapering the density of the plasma for optimal focusing. The underdense lens performance can be enhanced further by producing adiabatic plasma lenses to avoid the Oide limit on spot size due to synchrotron radiation by the electron beam. The plasma lens experiment at the Beam Test Facility (BTF) is designed to study the properties of plasma lenses in both overdense and underdense regimes. In particular, important issues such as electron beam matching, time response of the lens, lens aberrations and shot-to-shot reproducibility are being investigated.

  2. Multi electron species and shielding potentials in plasmas

    SciTech Connect

    Khan, Arroj A.; Murtaza, G.; Rasheed, A.; Jamil, M.

    2012-11-15

    The phenomenon of Debye shielding is investigated in electron ion plasmas using the approach of two temperature electrons. We get different profiles of potential for different parameters and observe that the potentials fall very slowly than the standard Coulomb and Debye potentials. The importance of work is pointed out in the introduction.

  3. Plasma-wall interaction in an electrostatic sheath of plasma containing a monoenergetic electron beam

    SciTech Connect

    Ou, Jing Zhao, Xiaoyun; Gan, Chunyun

    2016-04-15

    The plasma-wall interaction in the presence of a monoenergetic electron beam has been studied by taking into account the self-consistency among plasma transport in a collisionless electrostatic sheath, deposited energy flux at the wall and material thermal response for carbon and tungsten as wall materials. The variations of the potential drop across the sheath, ion velocity at the sheath edge, and surface temperature of material as a function of electron beam flux are explored in the presence of the electron emission. It is found that when electron beam does not dominate the sheath, potential drop across the sheath depends strongly on the material properties due to the impact of electron emission while the surface temperature of material shows monotonic variation. In the case of carbon wall, the electron beam may dominate the sheath at a certain electron beam concentration or energy. Under this circumstance, both the potential drop across the sheath and surface temperature of material demonstrate the sharp increasing transition. The development of local hot spot on the plasma facing material is caused by the enhanced ion energy flux instead of the electron beam energy flux. If the electron emission is not taken into account, as a smaller electron beam flux, both the potential drop across the sheath and surface temperature of material display the significant change and then it may be easier to develop for the local hot spot on the plasma facing material.

  4. Electron density and plasma dynamics of a colliding plasma experiment

    SciTech Connect

    Wiechula, J. Schönlein, A.; Iberler, M.; Hock, C.; Manegold, T.; Bohlender, B.; Jacoby, J.

    2016-07-15

    We present experimental results of two head-on colliding plasma sheaths accelerated by pulsed-power-driven coaxial plasma accelerators. The measurements have been performed in a small vacuum chamber with a neutral-gas prefill of ArH{sub 2} at gas pressures between 17 Pa and 400 Pa and load voltages between 4 kV and 9 kV. As the plasma sheaths collide, the electron density is significantly increased. The electron density reaches maximum values of ≈8 ⋅ 10{sup 15} cm{sup −3} for a single accelerated plasma and a maximum value of ≈2.6 ⋅ 10{sup 16} cm{sup −3} for the plasma collision. Overall a raise of the plasma density by a factor of 1.3 to 3.8 has been achieved. A scaling behavior has been derived from the values of the electron density which shows a disproportionately high increase of the electron density of the collisional case for higher applied voltages in comparison to a single accelerated plasma. Sequences of the plasma collision have been taken, using a fast framing camera to study the plasma dynamics. These sequences indicate a maximum collision velocity of 34 km/s.

  5. Ion temperature evolution in an ultracold neutral plasma

    SciTech Connect

    McQuillen, P. Strickler, T.; Langin, T.; Killian, T. C.

    2015-03-15

    We study the long-time evolution of the ion temperature in an expanding ultracold neutral plasma using spatially resolved, laser-induced-fluorescence spectroscopy. Adiabatic cooling reduces the ion temperature by an order of magnitude during the plasma expansion, to temperatures as low as 0.2 K. Cooling is limited by heat exchange between ions and the much hotter electrons. We also present evidence for an additional heating mechanism and discuss possible sources. Data are described by a model of the plasma evolution, including the effects of ion-electron heat exchange. We show that for appropriate initial conditions, the degree of Coulomb coupling of ions in the plasma increases during expansion.

  6. Effect of fast drifting electrons on electron temperature measurement with a triple Langmuir probe

    SciTech Connect

    Biswas, Subir Chowdhury, Satyajit; Pal, Rabindranath

    2015-08-14

    Triple Langmuir Probe (TLP) is a widely used diagnostics for instantaneous measurement of electron temperature and density in low temperature laboratory plasmas as well as in edge region of fusion plasma devices. Presence of a moderately energetic flowing electron component, constituting only a small fraction of the bulk electrons, is also a generally observed scenario in plasma devices, where plasmas are produced by electron impact ionization of neutrals. A theoretical analysis of its effect on interpretation of the TLP data for bulk electron temperature measurement is presented here assuming electron velocity distribution is not deviating substantially from a Maxwellian. The study predicts conventional expression from standard TLP theory to give overestimated value of bulk electron temperature. Correction factor is significant and largely depends on population density, temperature, and energy of the fast component. Experimental verification of theoretical results is obtained in the magnetized plasma linear experimental device of Saha Institute of Nuclear Physics where plasma is produced by an electron cyclotron resonance method and known to have a fast flowing electron component.

  7. Implementation of a new atomic basis for the He I equilibrium line ratio technique for electron temperature and density diagnostic in the SOL for H-mode plasmas in DIII-D

    SciTech Connect

    Burgos, JMM; Schmitz, O.; Unterberg, Ezekial A; Loch, S. D.; Ballance, C. P.

    2011-01-01

    Evaluating the ratio of selected helium lines allows for measurement of electron densities and temperatures. This technique is applied for L-mode plasmas at TEXTOR (O. Schmitz et al., Plasma Phys. Control. Fusion 50 (2008) 115004). We report our first efforts to extend it to H-mode plasma diagnostics in DIII-D. This technique depends on the accuracy of the atomic data used in the collisional radiative model (CRM). We present predictions for the electron temperatures and densities by using recently calculated R-Matrix With Pseudostates (RMPS) and Convergent Close-Coupling (CCC) electron-impact excitation and ionization data. We include contributions from higher Rydberg states by means of the projection matrix. These effects become significant for high electron density conditions, which are typical in H-mode. We apply a non-equilibrium model for the time propagation of the ionization balance to predict line emission profiles from experimental H-mode data from DIII-D. (C) 2010 Elsevier B.V. All rights reserved.

  8. Atomic processes in high temperature plasmas

    SciTech Connect

    Hahn, Y.

    1991-07-01

    This is the final report on the project Atomic Processes in High Temperature Plasmas', which has been completed in June 30, 1991. The original contract started in 1978. The dielectronic recombination (DR) rate coefficients were calculated for ions with the number of electrons N = 1, 2, 3, 4, 5, 10, 11, and 12. The result was then used to construct a new and improved rate formula. Other important resonant processes, which are closely related to DR, were also studied to interpret experiments and to test the DR theory. The plasma field and the density effects on the rate coefficients was found to be important, and a consistent correction procedure is being developed. The available data on the DR rates and their accuracy do not yet fully meet the requirement for plasma modeling; there are serious gaps in the available data, and the currently adopted theoretical procedure needs improvements. Critical assessment of the current status of the DR problem is presented, and possible future work needed is summarized.

  9. Time and space resolved measurement of the electron temperature, mass density and ionization state in the ablation plasma between two exploding Al wires

    SciTech Connect

    Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.; Hansen, S. B.

    2012-05-15

    We have determined the properties of plasma around and between two exploding wires using high-resolution x-ray absorption spectroscopy. Plasma densities and temperatures ranging from Greater-Than-Or-Equivalent-To 0.1g/cm{sup 3} and a few eV to less than 0.01 g/cm{sup 3} and 30 eV have been measured in experiments at Cornell University with two 40 {mu}m aluminum (Al) wires spaced 1 mm apart driven by {approx}150 kA peak current pulses with 100 ns rise time. The wire plasma was backlit by the 1.4-1.6 keV continuum radiation produced by a Mo wire X-pinch. The spectrometer employed two spherically bent quartz crystals to record the absorption and backlighter spectra simultaneously. The transition between the dense Al wire core and the coronal plasma is seen as a transition from cold K-edge absorption to Mg-, Na-, and finally Ne-like absorption at the boundary. In the plasma that accumulates between the wires, ionization states up to C-Like Al are observed. The spectrometer geometry and {approx}2{mu}m X-pinch source size provide 0.3 eV spectral resolution and 20 {mu}m spatial resolution enabling us to see 1s{yields} 2p satellite transitions as separate lines as well as O-, F-, and Ne-like 1s{yields} 3p transitions that have not been seen before. A step wedge was used to calibrate the transmission, enabling density to be measured within a factor of two and temperature to be measured within {+-}25%. A genetic algorithm was developed to fit synthetic spectra calculated using the collisional-radiative code SCRAM to the experimental spectra. In order to obtain agreement it was necessary to assume multiple plasma regions with variable thicknesses, thereby allowing the inferred plasma conditions to vary along the absorption path.

  10. Model of electron collecting plasma contactors

    NASA Technical Reports Server (NTRS)

    Davis, V. A.; Katz, I.; Mandell, M. J.; Parks, D. E.

    1991-01-01

    In laboratory experiments, plasma contactors are observed to collect ampere-level electron currents with low impedance. In order to extend the laboratory experience to the low-earth-orbit environment, a model of plasma contactors is being developed. Laboratory results are being used to support and validate the model development. The important physical processes observed in the laboratory are that the source plasma is separated from the background plasma by a double layer and that ionization of the expellant gas by the collected electrons creates the bulk of the ions that leave the source plasma. The model, which uses Poisson's equation with a physical charge density that includes the ion and electron components of both the source and the ambient plasmas, reproduces this phenomenon for typical experimental parameters. The calculations, in agreement with the laboratory results, show little convergence of the accelerated electrons. The angular momentum of the incoming electrons dramatically reduces the peak electron density. These electrons ionize enough gas to generate the source plasma. Calculations show that the increase in ionization rate with potential produces a steep rise in collected current with increasing potential as seen in the laboratory.

  11. Coupling between electron plasma waves in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Everett, M. J.; Lal, A.; Clayton, C. E.; Mori, W. B.; Joshi, C.; Johnston, T. W.

    1996-05-01

    A Lagrangian fluid model (cold plasma, fixed ions) is developed for analyzing the coupling between electron plasma waves. This model shows that a small wave number electron plasma wave (ω2,k2) will strongly affect a large wave number electron plasma wave (ω1,k1), transferring its energy into daughter waves or sidebands at (ω1+nω2,k1+nk2) in the lab frame. The accuracy of the model is checked via particle-in-cell simulations, which confirm that the energy in the mode at (ω1,k1) can be completely transferred to the sidebands at (ω1+nω2,k1+nk2) by the presence of the electron plasma mode at (ω2,k2). Conclusive experimental evidence for the generation of daughter waves via this coupling is then presented using time- and wave number-resolved spectra of the light from a probe laser coherently Thomson scattered by the electron plasma waves generated by the interaction of a two-frequency CO2 laser with a plasma.

  12. dc-plasma-sprayed electronic-tube device

    DOEpatents

    Meek, T.T.

    1982-01-29

    An electronic tube and associated circuitry which is produced by dc plasma arc spraying techniques is described. The process is carried out in a single step automated process whereby both active and passive devices are produced at very low cost. The circuitry is extremely reliable and is capable of functioning in both high radiation and high temperature environments. The size of the electronic tubes produced are more than an order of magnitude smaller than conventional electronic tubes.

  13. Spectroscopic measurements of electron temperature on VX-10

    NASA Astrophysics Data System (ADS)

    Sciamma, Ella; Lee, Charles; Bengtson, Roger; Jacobson, Verlin; Lavagni-Bolanos, Frank; McCaskill, Greg

    2004-11-01

    We have made spectroscopic measurements at several locations in the VX-10 experiment in the near UV, visible, and near IR spectral region. We estimate electron temperatures using a collisional radiative model. Residual gas analysis is also performed with plasma discharges. Quantitative estimates of plasma composition are also discussed.

  14. Correlation between excitation temperature and electron temperature with two groups of electron energy distributions

    SciTech Connect

    Park, Hoyong; Choe, Wonho; You, S. J.

    2010-10-15

    The relationship between the electron excitation temperature (T{sub exc}) determined by optical emission spectroscopy and the electron temperature (T{sub e}) using a rf-compensated Langmuir probe was investigated in argon capacitively coupled plasmas. In the experiment performed at the gas pressure range of 30 mTorr to 1 Torr and the rf power range of 5-37 W, the electron energy probability function (EEPF) obtained from the probe current versus voltage characteristic curve showed two energy groups of electrons. The measured EEPF demonstrated that the electron energy distribution changed from Druyvesteyn to single Maxwellian as the discharge current was increased and from bi-Maxwellian to Druyvesteyn as the pressure was increased. As a result, T{sub exc} showed a tendency identical to that of T{sub e} of the high energy part of electrons as pressure and rf power were varied. This suggests that electron temperature can be determined from the measured T{sub exc} through a calibration experiment by which the ratio between electron and excitation temperatures is measured.

  15. Effect of source tuning parameters on the plasma potential of heavy ions in the 18 GHz high temperature superconducting electron cyclotron resonance ion source.

    PubMed

    Rodrigues, G; Baskaran, R; Kukrety, S; Mathur, Y; Kumar, Sarvesh; Mandal, A; Kanjilal, D; Roy, A

    2012-03-01

    Plasma potentials for various heavy ions have been measured using the retarding field technique in the 18 GHz high temperature superconducting ECR ion source, PKDELIS [C. Bieth, S. Kantas, P. Sortais, D. Kanjilal, G. Rodrigues, S. Milward, S. Harrison, and R. McMahon, Nucl. Instrum. Methods B 235, 498 (2005); D. Kanjilal, G. Rodrigues, P. Kumar, A. Mandal, A. Roy, C. Bieth, S. Kantas, and P. Sortais, Rev. Sci. Instrum. 77, 03A317 (2006)]. The ion beam extracted from the source is decelerated close to the location of a mesh which is polarized to the source potential and beams having different plasma potentials are measured on a Faraday cup located downstream of the mesh. The influence of various source parameters, viz., RF power, gas pressure, magnetic field, negative dc bias, and gas mixing on the plasma potential is studied. The study helped to find an upper limit of the energy spread of the heavy ions, which can influence the design of the longitudinal optics of the high current injector being developed at the Inter University Accelerator Centre. It is observed that the plasma potentials are decreasing for increasing charge states and a mass effect is clearly observed for the ions with similar operating gas pressures. In the case of gas mixing, it is observed that the plasma potential minimizes at an optimum value of the gas pressure of the mixing gas and the mean charge state maximizes at this value. Details of the measurements carried out as a function of various source parameters and its impact on the longitudinal optics are presented.

  16. Effect of source tuning parameters on the plasma potential of heavy ions in the 18 GHz high temperature superconducting electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Rodrigues, G.; Baskaran, R.; Kukrety, S.; Mathur, Y.; Kumar, Sarvesh; Mandal, A.; Kanjilal, D.; Roy, A.

    2012-03-01

    Plasma potentials for various heavy ions have been measured using the retarding field technique in the 18 GHz high temperature superconducting ECR ion source, PKDELIS [C. Bieth, S. Kantas, P. Sortais, D. Kanjilal, G. Rodrigues, S. Milward, S. Harrison, and R. McMahon, Nucl. Instrum. Methods B 235, 498 (2005), 10.1016/j.nimb.2005.03.232; D. Kanjilal, G. Rodrigues, P. Kumar, A. Mandal, A. Roy, C. Bieth, S. Kantas, and P. Sortais, Rev. Sci. Instrum. 77, 03A317 (2006), 10.1063/1.2164887]. The ion beam extracted from the source is decelerated close to the location of a mesh which is polarized to the source potential and beams having different plasma potentials are measured on a Faraday cup located downstream of the mesh. The influence of various source parameters, viz., RF power, gas pressure, magnetic field, negative dc bias, and gas mixing on the plasma potential is studied. The study helped to find an upper limit of the energy spread of the heavy ions, which can influence the design of the longitudinal optics of the high current injector being developed at the Inter University Accelerator Centre. It is observed that the plasma potentials are decreasing for increasing charge states and a mass effect is clearly observed for the ions with similar operating gas pressures. In the case of gas mixing, it is observed that the plasma potential minimizes at an optimum value of the gas pressure of the mixing gas and the mean charge state maximizes at this value. Details of the measurements carried out as a function of various source parameters and its impact on the longitudinal optics are presented.

  17. Effect of source tuning parameters on the plasma potential of heavy ions in the 18 GHz high temperature superconducting electron cyclotron resonance ion source

    SciTech Connect

    Rodrigues, G.; Mathur, Y.; Kumar, Sarvesh; Mandal, A.; Kanjilal, D.; Roy, A.; Baskaran, R.; Kukrety, S.

    2012-03-15

    Plasma potentials for various heavy ions have been measured using the retarding field technique in the 18 GHz high temperature superconducting ECR ion source, PKDELIS [C. Bieth, S. Kantas, P. Sortais, D. Kanjilal, G. Rodrigues, S. Milward, S. Harrison, and R. McMahon, Nucl. Instrum. Methods B 235, 498 (2005); D. Kanjilal, G. Rodrigues, P. Kumar, A. Mandal, A. Roy, C. Bieth, S. Kantas, and P. Sortais, Rev. Sci. Instrum. 77, 03A317 (2006)]. The ion beam extracted from the source is decelerated close to the location of a mesh which is polarized to the source potential and beams having different plasma potentials are measured on a Faraday cup located downstream of the mesh. The influence of various source parameters, viz., RF power, gas pressure, magnetic field, negative dc bias, and gas mixing on the plasma potential is studied. The study helped to find an upper limit of the energy spread of the heavy ions, which can influence the design of the longitudinal optics of the high current injector being developed at the Inter University Accelerator Centre. It is observed that the plasma potentials are decreasing for increasing charge states and a mass effect is clearly observed for the ions with similar operating gas pressures. In the case of gas mixing, it is observed that the plasma potential minimizes at an optimum value of the gas pressure of the mixing gas and the mean charge state maximizes at this value. Details of the measurements carried out as a function of various source parameters and its impact on the longitudinal optics are presented.

  18. Thermal Improvement and Stability of Si3N4/GeNx/p- and n-Ge Structures Prepared by Electron-Cyclotron-Resonance Plasma Nitridation and Sputtering at Room Temperature

    NASA Astrophysics Data System (ADS)

    Fukuda, Yukio; Okamoto, Hiroshi; Iwasaki, Takuro; Izumi, Kohei; Otani, Yohei; Ishizaki, Hiroki; Ono, Toshiro

    2012-09-01

    This paper reports on the thermal improvement of Si3N4/GeNx/Ge structures. After the Si3N4 (5 nm)/GeNx (2 nm) stacks were prepared on Ge substrates by electron-cyclotron-resonance plasma nitridation and sputtering at room temperature, they were thermally annealed in atmospheric N2 + 10% H2 ambient at temperatures from 400 to 600 °C. It was demonstrated that the electronic properties of the GeNx/Ge interfaces were thermally improved at temperatures of up to 500 °C with a minimum interface trap density (Dit) of ˜1×1011 cm-2 eV-1 near the Ge midgap, whereas the interface properties were slightly degraded after annealing at 600 °C with a minimum Dit value of ˜4×1011 cm-2 eV-1.

  19. Ion Temperature Control of the Io Plasma Torus

    NASA Technical Reports Server (NTRS)

    Delamere, P. A.; Schneider, N. M.; Steffl, A. J.; Robbins, S. J.

    2005-01-01

    We report on observational and theoretical studies of ion temperature in the Io plasma torus. Ion temperature is a critical factor for two reasons. First, ions are a major supplier of energy to the torus electrons which power the intense EUV emissions. Second, ion temperature determines the vertical extent of plasma along field lines. Higher temperatures spread plasma out, lowers the density and slows reaction rates. The combined effects can play a controlling role in torus energetics and chemistry. An unexpected tool for the study of ion temperature is the longitudinal structure in the plasma torus which often manifests itself as periodic brightness variations. Opposite sides of the torus (especially magnetic longitudes 20 and 200 degrees) have been observed on numerous occasions to have dramatically different brightness, density, composition, ionization state, electron temperature and ion temperature. These asymmetries must ultimately be driven by different energy flows on the opposite sides, presenting an opportunity to observe key torus processes operating under different conditions. The most comprehensive dataset for the study of longitudinal variations was obtained by the Cassini UVIS instrument during its Jupiter flyby. Steffl (Ph.D. thesis, 2005) identified longitudinal variations in all the quantities listed above wit the exception of ion temperature. We extend his work by undertaking the first search for such variation in the UVIS dataset. We also report on a 'square centimeter' model of the torus which extend the traditional 'cubic centimeter' models by including the controlling effects of ion temperature more completely.

  20. Negative plasma potential relative to electron-emitting surfaces.

    PubMed

    Campanell, M D

    2013-09-01

    Most works on plasma-wall interaction predict that with strong electron emission, a nonmonotonic "space-charge-limited" (SCL) sheath forms where the plasma potential is positive relative to the wall. We show that a fundamentally different sheath structure is possible where the potential monotonically increases toward a positively charged wall that is shielded by a single layer of negative charge. No ion-accelerating presheath exists in the plasma and the ion wall flux is zero. An analytical solution of the "inverse sheath" regime is demonstrated for a general plasma-wall system where the plasma electrons and emitted electrons are Maxwellian with different temperatures. Implications of the inverse sheath effect are that (a) the plasma potential is negative, (b) ion sputtering vanishes, (c) no charge is lost at the wall, and (d) the electron energy flux is thermal. To test empirically what type of sheath structure forms under strong emission, a full plasma bounded by strongly emitting walls is simulated. It is found that inverse sheaths form at the walls and ions are confined in the plasma. This result differs from past particle-in-cell simulation studies of emission which contain an artificial "source sheath" that accelerates ions to the wall, leading to a SCL sheath at high emission intensity.

  1. Quantitative diagnostics of reactive, multicomponent low-temperature plasmas

    NASA Astrophysics Data System (ADS)

    Schwarz-Selinger, Thomas

    2013-09-01

    The special emphasis in this work is put on the quantitative determination of the plasma composition of an inductively coupled low temperature plasma (ICP). Several standard plasma diagnostic techniques were applied. As a test case for a multi-component low-temperature plasma argon-hydrogen as well as argon-hydrogen-nitrogen mixed plasmas were investigated. For steady-state plasma operation the ion density and electron temperature were determined with a single tip Langmuir probe. A multi-grid miniature retarding-field analyzer was used to measure the mass integrated ion flux. An energy-dispersive mass spectrometer - a so-called plasma monitor (PM) - was applied to sample ions from the plasma to derive the ion composition. The degree of dissociation of hydrogen and the gas temperature were derived from optical emission spectroscopy. The gas temperature was estimated by the rotational distribution of the Q-branch lines of the hydrogen Fulcher- α diagonal band for the argon-hydrogen mixed plasmas and from the second positive system of N2 in argon-hydrogen-nitrogen mixed plasmas. The degree of dissociation of hydrogen was measured by actinometry. The influence of the substrate material of the counter electrode (stainless steel, copper, tungsten, Macor, and aluminium) on the atomic hydrogen concentration was investigated by OES. In addition, ionization-threshold mass spectrometry (ITMS) was used to determine the densities of atomic nitrogen (N) and atomic hydrogen (H and D). Pulsed plasma operation was applied to directly measure the loss rate of H, D and N in the afterglow from the temporal decay of the ITMS signal. From these data the wall loss probability of atomic hydrogen was determined. Furthermore, a zero-dimensional rate equation model was devised to explain the ion composition in these mixed plasmas with different admixture ratios. In addition to the experimental data on electron density, gas temperature, total pressure, atomic hydrogen density, and Ar, H2

  2. Electronic Ambient-Temperature Recorder

    NASA Technical Reports Server (NTRS)

    Russell, Larry; Barrows, William

    1995-01-01

    Electronic temperature-recording unit stores data in internal memory for later readout. Records temperatures from minus 40 degrees to plus 60 degrees C at intervals ranging from 1.875 to 15 minutes. With all four data channels operating at 1.875-minute intervals, recorder stores at least 10 days' data. For only one channel at 15-minute intervals, capacity extends to up to 342 days' data. Developed for recording temperatures of instruments and life-science experiments on satellites, space shuttle, and high-altitude aircraft. Adaptable to such terrestrial uses as recording temperatures of perishable goods during transportation and of other systems or processes over long times. Can be placed directly in environment to monitor.

  3. A model of electron collecting plasma contractors

    NASA Technical Reports Server (NTRS)

    Davis, V. A.; Katz, I.; Mandell, M. J.; Parks, D. E.

    1989-01-01

    A model of plasma contractors is being developed, which can be used to describe electron collection in a laboratory test tank and in the space environment. To validate the model development, laboratory experiments are conducted in which the source plasma is separated from the background plasma by a double layer. Model calculations show that an increase in ionization rate with potential produces a steep rise in collected current with increasing potential.

  4. A model of electron collecting plasma contractors

    NASA Technical Reports Server (NTRS)

    Davis, V. A.; Katz, I.; Mandell, M. J.; Parks, D. E.

    1989-01-01

    A model of plasma contractors is being developed, which can be used to describe electron collection in a laboratory test tank and in the space environment. To validate the model development, laboratory experiments are conducted in which the source plasma is separated from the background plasma by a double layer. Model calculations show that an increase in ionization rate with potential produces a steep rise in collected current with increasing potential.

  5. Measurements of plasma bremsstrahlung and plasma energy density produced by electron cyclotron resonance ion source plasmas

    NASA Astrophysics Data System (ADS)

    Noland, Jonathan David

    2011-12-01

    The goal of this dissertation was to gain an understanding on the relative importance of microwave power, neutral pressure, and magnetic field configuration on the behavior of the hot electrons within an Electron Cyclotron Resonance Ion Source (ECRIS) plasma. This was carried out through measurement of plasma bremsstrahlung with both NaI(Tl) (hv > 30 keV) and CdTe (2 keV < hv < 70 keV) x-ray detectors, and through measurement of the plasma energy density with a diamagnetic loop placed around the plasma chamber. We also examined the anisotropy in x-ray power by simultaneously measuring the x-ray spectra in two orthogonal directions: radially and axially, using NaI(Tl) detectors. We have seen that for a 6.4 GHz ECRIS, both the x-ray power produced by confined electrons and the plasma energy density behave logarithmically with microwave power. The x-ray flux created by electrons lost from the plasma, however, does not saturate. Thus, the small increase in plasma density that occurred at high microwave powers (> 150 W on a 6.4 GHz ECRIS) was accompanied by a large increase in total x-ray power. We suggest that the saturation of x-ray power and plasma energy density was due to rf-induced pitch-angle scattering of the electrons. X-ray power and plasma energy density were also shown to saturate with neutral pressure, and to increase nearly linearly as the gradient of the magnetic field in the resonance zone was decreased. All of these findings were in agreement with the theoretical models describing ECRIS plasmas. We have discussed the use of a diamagnetic loop as a means of exploring various plasma time scales on a relative basis. Specifically, we focused much of our attention on studying how changing ion source parameters, such as microwave power and neutral pressure, would effect the rise and decay of the integrated diamagnetic signal, which can be related to plasma energy density. We showed that increasing microwave power lowers the e-fold times at both the leading

  6. Plasma production for electron acceleration by resonant plasma wave

    NASA Astrophysics Data System (ADS)

    Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Di Pirro, G. P.; Filippi, F.; Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R.; Romeo, S.; Ferrario, M.

    2016-09-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10-100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC_LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.

  7. Experimental studies of thermal fluctuations in electron plasmas

    NASA Astrophysics Data System (ADS)

    Shiga, Nobuyasu

    We have detected the thermally excited charge fluctuations in pure electron plasmas over a temperature range of 0.05 < kBT < 10eV. These fluctuation spectra have both a global mode component and a random particle fluctuation component. At low temperatures, the mtheta = 0, kz = 1, 2, 3,.... Trivelpiece-Gould modes are weakly damped and dominate, since the random particle component is suppressed by Debye-shielding. As the temperature increases, the broad random particle component increases in between the modes. We have developed 3 different non-perturbative methods to determine the plasma temperature. These 3 methods are valid in different regimes depending on the Debye length normalized by the plasma radius lDRp , and on the plasma length normalized by the plasma radius LpRp . The first method focuses on the near-Lorentzian spectrum of thermal fluctuations near a weakly damped mode. Each weakly damped mode has the same energy as the electron temperature. The measured emission spectrum together with a plasma-antenna impedance calibration uniquely determines the temperature of the plasma, using Nyquist theorem. Experimentally this method gives the correct temperature, agreeing with the standard "dump" temperature measurements when lDRp < 0.3. The second method utilizes the emission spectrum over a broad frequency range encompassing several modes and the non-resonant fluctuations between modes. The Nyquist theorem together with a kinetic theory calculation of the plasma-antenna impedance determines the temperature from the broad fluctuation spectrum. Kinetic theory implicitly assumes that Landau damping is the only damping mechanism, and also assumes an infinite length for the plasma. This method works if lDRp > 0.2 so that Landau damping is dominant, and if LpRp > 20 so that finite-length corrections to Landau damping are negligible. The third method utilizes the total (frequency-integrated) number delta N of the fluctuating image charges on the antenna, and

  8. Plasma chemistry in electron-beam sustained discharges

    NASA Astrophysics Data System (ADS)

    Turner, Miles

    2016-09-01

    There are many emerging applications that exploit the exotic chemical characteristics of plasmas. Some of these applications, if deployed on an industrial scale, involve processing much larger volumes of gas than seems reasonable using any atmospheric pressure plasma source in wide use today. We note that an electron-beam sustained discharge permits the creation of a atmospheric pressure plasma with reasonable uniformity, large volme, and widely controllable electron temperature. Robust and durable electron beam sources now exist that would facilitate such applications. In this paper we discuss the general advantages of this approach, and we present a modelling study concerned with the production of NO in mixtures of N2 and O2, looking towards plasma aided manufacturing of fertilizers.

  9. [Low temperature plasma technology for biomass refinery].

    PubMed

    Fu, Xiaoguo; Chen, Hongzhang

    2014-05-01

    Biorefinery that utilizes renewable biomass for production of fuels, chemicals and bio-materials has become more and more important in chemical industry. Recently, steam explosion technology, acid and alkali treatment are the main biorefinery treatment technologies. Meanwhile, low temperature plasma technology has attracted extensive attention in biomass refining process due to its unique chemical activity and high energy. We systemically summarize the research progress of low temperature plasma technology for pretreatment, sugar platflow, selective modification, liquefaction and gasification in biomass refinery. Moreover, the mechanism of low temperature plasma in biorefinery and its further development were also discussed.

  10. Spectroscopic temperature measurements of non-equilibrium plasmas

    SciTech Connect

    Back, C.A.; Glenzer, S.H.; Lee, R.W.; MacGowan, B.J.

    1996-04-24

    The characterization of laser-produced plasmas has required the application of spectroscopic techniques to non-standard conditions where kinetics models have not been extensively tested. The plasmas are produced by the Nova laser for the study of inertial confinement fusion, can be mm in size, and evolve on sub-nanosecond time scales. These targets typically achieve electron temperatures from 2-4 keV and electron densities of 10{sup 20}-10{sup 22} cm{sup {minus}3}. The authors have measured the electron temperature of two types of targets: bags of gas and hohlraums, Au cylinders with laser entrance holes in the flat ends. By comparing data from different targets, they examine the time-dependence of spectroscopic plasma diagnostics.

  11. Simulating a Maxwellian plasma using an electron beam ion trap

    SciTech Connect

    Savin, D. W.; Beiersdorfer, P.; Kahn, S. M.; Beck, B. R.; Brown, G. V.; Gu, M. F.; Liedahl, D. A.; Scofield, J. H.

    2000-09-01

    We describe a technique for producing a Maxwell-Boltzmann electron energy distribution using an electron beam ion trap (EBIT). The technique was implemented on the Lawrence Livermore EBIT to simulate Maxwellian plasmas. We discuss technical and experimental issues related to these simulations. To verify the fidelity of the quasi-Maxwellian, we have measured line emission due to dielectronic recombination (DR) and electron impact excitation (EIE) of heliumlike neon, magnesium, and argon for a range of simulated electron temperatures. The ratio of DR to EIE lines in heliumlike ions is a well understood electron temperature diagnostic. The spectroscopically inferred quasi-Maxwellian temperatures are in excellent agreement with the simulated temperatures. (c) 2000 American Institute of Physics.

  12. Development of plasma cathode electron guns

    NASA Astrophysics Data System (ADS)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  13. Spontaneous emission near the electron plasma frequency in a plasma with a runaway electron tail

    NASA Technical Reports Server (NTRS)

    Freund, H. P.; Lee, L. C.; Wu, C. S.

    1978-01-01

    Spontaneous emission of radiation with frequencies near the electron plasma frequency is studied for a plasma which consists of both thermal and runaway electrons. It is found that a substantial enhancement of the spontaneous radiation intensity can occur in this frequency regime via a Cherenkov resonance with the runaway electrons. Numerical analysis indicates that, for reasonable estimates of densities and energies, the plasma-frequency radiation can attain levels greater than the peak thermal emission at the second gyroharmonic.

  14. Plasma Interaction with Electron-Emitting Surfaces

    SciTech Connect

    Campanell, Michael

    2014-09-01

    Electron emission from surfaces occurs in many plasma systems. Several types including secondary, thermionic and photon-induced emissions are intense under certain conditions. Understanding the effects of emission on the sheaths that govern plasma-surface interaction is important. This dissertation predicts some emitting sheath phenomena that were not reported in past studies. For example, most previous theoretical models assumed that an emitting sheath potential is always negative and that ions always accelerate into the wall. We show when the emission is intense that the sheath potential can become positive, fundamentally changing how the plasma and wall interact. In this inverse sheath state, ions are repelled, suggesting for instance that (a) no presheath exists in the plasma interior, (b) emitting walls could be used in applications to stop sputtering. Another topic considered is the transit of emitted electrons across the plasma to other surfaces, which is possible in low collisionality plasma systems. When transit occurs, the flux balance is a complex global problem where the sheaths at opposite surfaces are coupled through their exchange of emitted electrons. We also show that secondary emission can trigger a variety of sheath instability phenomena that change the state of the plasma-wall system or cause oscillations preventing steady state. Lastly, we analyze a mechanism where emitted electrons return to the same surface and knock out secondaries, which return and knock out more secondaries, etc., feedback amplifying the emission intensity. The four phenomena will be analyzed theoretically and verified with particle-in-cell simulations: (a) inverse sheath, (b) sheath coupling via transiting electrons, (c) sheath instabilities, (d) returning electron amplification. Consequences of these processes on the sheath potentials, wall heating, loss rate of charge, and cross field transport (near-wall conductivity) are discussed throughout. Possible implications are

  15. Approximate equations of state in two-temperature plasma mixtures

    SciTech Connect

    Ramshaw, John D.; Cook, Andrew W.

    2014-02-15

    Approximate thermodynamic state relations for multicomponent atomic and molecular gas mixtures are often constructed by artificially partitioning the mixture into its constituent materials and requiring the separated materials to be in temperature and pressure equilibrium. Iterative numerical algorithms have been employed to enforce this equilibration and compute the resulting approximate state relations in single-temperature mixtures. In partially ionized gas mixtures, there is both theoretical and empirical evidence that equilibrating the chemical potentials, number densities, or partial pressures of the free electrons is likely to produce more accurate results than equilibrating the total pressures. Moreover, in many situations of practical interest the free electrons and heavy particles have different temperatures. In this paper, we present a generalized algorithm for equilibrating the heavy-particle and electron temperatures and a third user-specified independent thermodynamic variable in a two-temperature plasma mixture. Test calculations based on the equilibration of total pressure vs. electron pressure are presented for three different mixtures.

  16. Diagnosing pure-electron plasmas with internal particle flux probes.

    PubMed

    Kremer, J P; Pedersen, T Sunn; Marksteiner, Q; Lefrancois, R G; Hahn, M

    2007-01-01

    Techniques for measuring local plasma potential, density, and temperature of pure-electron plasmas using emissive and Langmuir probes are described. The plasma potential is measured as the least negative potential at which a hot tungsten filament emits electrons. Temperature is measured, as is commonly done in quasineutral plasmas, through the interpretation of a Langmuir probe current-voltage characteristic. Due to the lack of ion-saturation current, the density must also be measured through the interpretation of this characteristic thereby greatly complicating the measurement. Measurements are further complicated by low densities, low cross field transport rates, and large flows typical of pure-electron plasmas. This article describes the use of these techniques on pure-electron plasmas in the Columbia Non-neutral Torus (CNT) stellarator. Measured values for present baseline experimental parameters in CNT are phi(p)=-200+/-2 V, T(e)=4+/-1 eV, and n(e) on the order of 10(12) m(-3) in the interior.

  17. Electronic Broadening operator for relativistic plasmas

    SciTech Connect

    Meftah, M. T.; Naam, A.

    2008-10-22

    In this work we review some aspects of the semiclassical dipole impact approximation for isolated ion lines in relativistic plasma. Mainly we focuss our work on the collision operator for relativistic electrons. In this case, the electron trajectory around a positive charge in the plasma differs drastically from those known earlier as hyperbolic. The effect of this difference on the collision operator is discussed with respect the various plasma conditions. Some theoretical and practical aspects of lines -shape calculations are discussed. Detailed calculations are performed for the collision operator in the semiclassical (dipole) impact approximation.

  18. Self-effect in expanding electron beam plasma

    SciTech Connect

    Garcia, M

    1999-05-07

    An analytical model of plasma flow from a metal plate hit by an intense, pulsed, electron beam aims to bridge the gap between radiation-hydrodynamics simulations and experiments, and to quantify the self-effect of the electron beam penetrating the flow. Does the flow disrupt the tight focus of the initial electron bunch, or later pulses in a train? This work aims to model the spatial distribution of plasma speed, density, degree of ionization, and magnetization to inquire. The initial solid density, several eV plasma expands to 1 cm and 10{sup {minus}4} relative density by 2 {micro}s, beyond which numerical simulations are imprecise. Yet, a Faraday cup detector at the ETA-II facility is at 25 cm from the target and observes the flow after 50 {micro}s. The model helps bridge this gap. The expansion of the target plasma into vacuum is so rapid that the ionized portion of the flow departs from local thermodynamic equilibrium. When the temperature (in eV) in a parcel of fluid drops below V{sub i} x [(2{gamma} - 2)/(5{gamma} + 17)], where V{sub i} is the ionization potential of the target metal (7.8 eV for tantalum), and {gamma} is the ratio of specific heats (5/3 for atoms), then the fractional ionization and electron temperature in that parcel remain fixed during subsequent expansion. The freezing temperature as defined here is V{sub i}/19. The balance between the self-pinching force and the space charge repulsion of an electron beam changes on penetrating a flow: (i) the target plasma cancels the space-charge field, (ii) internal eddy currents arise to counter the magnetization of relativistic electrons, and (iii) electron beam heating alters the flow magnetization by changing the plasma density gradient and the magnitude of the conductivity.

  19. Industrial Applications of Low Temperature Plasmas

    SciTech Connect

    Bardsley, J N

    2001-03-15

    The use of low temperature plasmas in industry is illustrated by the discussion of four applications, to lighting, displays, semiconductor manufacturing and pollution control. The type of plasma required for each application is described and typical materials are identified. The need to understand radical formation, ionization and metastable excitation within the discharge and the importance of surface reactions are stressed.

  20. Towards a Quantitative Analysis of the Temperature Dependence of Electron Attachment Processes

    DTIC Science & Technology

    2016-06-24

    The success in analyzing temperature and pressure dependences of EA to CF3, a process of importance in industrial plasma etching of chips, prompted...atmospheric chemistry, combustion, and plasma chemistry. 15. SUBJECT TERMS EOARD, chemical kinetics, plasma chemistry, hypersonic plasma 16. SECURITY...kinetics such as atmospheric chemistry, combustion, and plasma chemistry. 2. Introduction Dissociative and/or nondissociative electron attachment to

  1. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    DOE PAGES

    Adamovich, I.; Baalrud, S. D.; Bogaerts, A.; ...

    2017-07-14

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic updates of the Plasma Roadmap. The continuously growing interdisciplinary nature of the low temperature plasma field and its equally broad range of applications are making it increasingly difficult to identify major challenges that encompass all of the many sub-fields and applications. This intellectual diversity is ultimately a strength of the field. The currentmore » state of the art for the 19 sub-fields addressed in this roadmap demonstrates the enviable track record of the low temperature plasma field in the development of plasmas as an enabling technology for a vast range of technologies that underpin our modern society. At the same time, the many important scientific and technological challenges shared in this roadmap show that the path forward is not only scientifically rich but has the potential to make wide and far reaching contributions to many societal challenges.« less

  2. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    NASA Astrophysics Data System (ADS)

    Adamovich, I.; Baalrud, S. D.; Bogaerts, A.; Bruggeman, P. J.; Cappelli, M.; Colombo, V.; Czarnetzki, U.; Ebert, U.; Eden, J. G.; Favia, P.; Graves, D. B.; Hamaguchi, S.; Hieftje, G.; Hori, M.; Kaganovich, I. D.; Kortshagen, U.; Kushner, M. J.; Mason, N. J.; Mazouffre, S.; Mededovic Thagard, S.; Metelmann, H.-R.; Mizuno, A.; Moreau, E.; Murphy, A. B.; Niemira, B. A.; Oehrlein, G. S.; Petrovic, Z. Lj; Pitchford, L. C.; Pu, Y.-K.; Rauf, S.; Sakai, O.; Samukawa, S.; Starikovskaia, S.; Tennyson, J.; Terashima, K.; Turner, M. M.; van de Sanden, M. C. M.; Vardelle, A.

    2017-08-01

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic updates of the Plasma Roadmap. The continuously growing interdisciplinary nature of the low temperature plasma field and its equally broad range of applications are making it increasingly difficult to identify major challenges that encompass all of the many sub-fields and applications. This intellectual diversity is ultimately a strength of the field. The current state of the art for the 19 sub-fields addressed in this roadmap demonstrates the enviable track record of the low temperature plasma field in the development of plasmas as an enabling technology for a vast range of technologies that underpin our modern society. At the same time, the many important scientific and technological challenges shared in this roadmap show that the path forward is not only scientifically rich but has the potential to make wide and far reaching contributions to many societal challenges.

  3. Recycling of the Electronic Waste Applying the Plasma Reactor Technology

    NASA Astrophysics Data System (ADS)

    Lázár, Marián; Jasminská, Natália; Čarnogurská, Mária; Dobáková, Romana

    2016-12-01

    The following paper discusses a high-temperature gasification process and melting of electronic components and computer equipment using plasma reactor technology. It analyses the marginal conditions of batch processing, as well as the formation of solid products which result from the procedure of waste processing. Attention is also paid to the impact of the emerging products on the environment.

  4. Effect of secondary electron emission on the plasma sheath

    SciTech Connect

    Langendorf, S. Walker, M.

    2015-03-15

    In this experiment, plasma sheath potential profiles are measured over boron nitride walls in argon plasma and the effect of secondary electron emission is observed. Results are compared to a kinetic model. Plasmas are generated with a number density of 3 × 10{sup 12} m{sup −3} at a pressure of 10{sup −4} Torr-Ar, with a 1%–16% fraction of energetic primary electrons. The sheath potential profile at the surface of each sample is measured with emissive probes. The electron number densities and temperatures are measured in the bulk plasma with a planar Langmuir probe. The plasma is non-Maxwellian, with isotropic and directed energetic electron populations from 50 to 200 eV and hot and cold Maxwellian populations from 3.6 to 6.4 eV and 0.3 to 1.3 eV, respectively. Plasma Debye lengths range from 4 to 7 mm and the ion-neutral mean free path is 0.8 m. Sheath thicknesses range from 20 to 50 mm, with the smaller thickness occurring near the critical secondary electron emission yield of the wall material. Measured floating potentials are within 16% of model predictions. Measured sheath potential profiles agree with model predictions within 5 V (∼1 T{sub e}), and in four out of six cases deviate less than the measurement uncertainty of 1 V.

  5. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    NASA Astrophysics Data System (ADS)

    Lunov, O.; Churpita, O.; Zablotskii, V.; Deyneka, I. G.; Meshkovskii, I. K.; Jäger, A.; Syková, E.; Kubinová, Š.; Dejneka, A.

    2015-02-01

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin-stained rat skin sections from plasma-treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

  6. Electron Beam Diagnostics in Plasmas Based on Electron Beam Ionization

    NASA Astrophysics Data System (ADS)

    Leonhardt, Darrin; Leal-Quiros, Edbertho; Blackwell, David; Walton, Scott; Murphy, Donald; Fernsler, Richard; Meger, Robert

    2001-10-01

    Over the last few years, electron beam ionization has been shown to be a viable generator of high density plasmas with numerous applications in materials modification. To better understand these plasmas, we have fielded electron beam diagnostics to more clearly understand the propagation of the beam as it travels through the background gas and creates the plasma. These diagnostics vary greatly in sophistication, ranging from differentially pumped systems with energy selective elements to metal 'hockey pucks' covered with thin layers of insulation to electrically isolate the detector from the plasma but pass high energy beam electrons. Most importantly, absolute measurements of spatially resolved beam current densities are measured in a variety of pulsed and continuous beam sources. The energy distribution of the beam current(s) will be further discussed, through experiments incorporating various energy resolving elements such as simple grids and more sophisticated cylindrical lens geometries. The results are compared with other experiments of high energy electron beams through gases and appropriate disparities and caveats will be discussed. Finally, plasma parameters are correlated to the measured beam parameters for a more global picture of electron beam produced plasmas.

  7. Electron temperature and density relationships in coronal mass ejections

    NASA Technical Reports Server (NTRS)

    Hammond, C. M.; Phillips, J. L.; Balogh, A.

    1995-01-01

    We examine 10 coronal mass ejections from the in-ecliptic portion of the Ulysses mission. Five of these CMEs are magnetic clouds. In each case we observe an inverse relationship between electron temperature and density. For protons this relationship is less clear. Earlier work has shown a similar inverse relationship for electrons inside magnetic clouds and interpreted it to mean that the polytropic index governing the expansion of electrons is less than unity. This requires electrons to be heated as the CME expands. We offer an alternative view that the inverse relationship between electron temperature and density is caused by more rapid cooling of the denser plasma through collisions. More rapid cooling of denser plasma has been shown for 1 AU measurements in the solar wind. As evidence for this hypothesis we show that the denser plasma inside the CMEs tends to be more isotropic indicating a different history of collisions for the dense plasma. Thus, although the electron temperature inside CMEs consistently shows an inverse correlation with the density, this is not an indication of the polytropic index of the plasma but instead supports the idea of collisional modification of the electrons during their transit from the sun.

  8. Electron temperature and density relationships in coronal mass ejections

    NASA Technical Reports Server (NTRS)

    Hammond, C. M.; Phillips, J. L.; Balogh, A.

    1995-01-01

    We examine 10 coronal mass ejections from the in-ecliptic portion of the Ulysses mission. Five of these CMEs are magnetic clouds. In each case we observe an inverse relationship between electron temperature and density. For protons this relationship is less clear. Earlier work has shown a similar inverse relationship for electrons inside magnetic clouds and interpreted it to mean that the polytropic index governing the expansion of electrons is less than unity. This requires electrons to be heated as the CME expands. We offer an alternative view that the inverse relationship between electron temperature and density is caused by more rapid cooling of the denser plasma through collisions. More rapid cooling of denser plasma has been shown for 1 AU measurements in the solar wind. As evidence for this hypothesis we show that the denser plasma inside the CMEs tends to be more isotropic indicating a different history of collisions for the dense plasma. Thus, although the electron temperature inside CMEs consistently shows an inverse correlation with the density, this is not an indication of the polytropic index of the plasma but instead supports the idea of collisional modification of the electrons during their transit from the sun.

  9. Electron presheaths: the outsized influence of positive boundaries on plasmas

    NASA Astrophysics Data System (ADS)

    Yee, B. T.; Scheiner, B.; Baalrud, S. D.; Barnat, E. V.; Hopkins, M. M.

    2017-02-01

    Electron sheaths form near the surface of objects biased more positive than the plasma potential, such as a Langmuir probe collecting electron saturation current. Generally, the formation of electron sheaths requires that the electron-collecting area be sufficiently smaller (\\sqrt{2.3{m}e/M} times) than the ion-collecting area. They are commonly thought to be local phenomena that collect the random thermal electron current, but do not otherwise perturb a plasma. Here, using experiments on an electrode embedded in a wall in a helium discharge, particle-in-cell simulations, and theory it is shown that under low temperature plasma conditions ({T}e\\gg {T}i) electron sheaths are far from local. Instead, a long presheath region (27 mm, approximately an electron’s mean free path) extends into the plasma where electrons are accelerated via a pressure gradient to a flow speed exceeding the electron thermal speed at the sheath edge. This fast flow is found to excite instabilities, causing strong fluctuations near the sheath edge.

  10. Time-resolved aluminium laser-induced plasma temperature measurements

    NASA Astrophysics Data System (ADS)

    Surmick, D. M.; Parigger, C. G.

    2014-11-01

    We seek to characterize the temperature decay of laser-induced plasma near the surface of an aluminium target from laser-induced breakdown spectroscopy measurements of aluminium alloy sample. Laser-induced plasma are initiated by tightly focussing 1064 nm, nanosecond pulsed Nd:YAG laser radiation. Temperatures are inferred from aluminium monoxide spectra viewed at systematically varied time delays by comparing experimental spectra to theoretical calculations with a Nelder Mead algorithm. The temperatures are found to decay from 5173 ± 270 to 3862 ± 46 Kelvin from 10 to 100 μs time delays following optical breakdown. The temperature profile along the plasma height is also inferred from spatially resolved spectral measurements and the electron number density is inferred from Stark broadened Hβ spectra.

  11. Beltrami–Bernoulli equilibria in plasmas with degenerate electrons

    SciTech Connect

    Berezhiani, V. I.; Shatashvili, N. L.; Mahajan, S. M.

    2015-02-15

    A new class of Double Beltrami–Bernoulli equilibria, sustained by electron degeneracy pressure, is investigated. It is shown that due to electron degeneracy, a nontrivial Beltrami–Bernoulli equilibrium state is possible even for a zero temperature plasma. These states are, conceptually, studied to show the existence of new energy transformation pathways converting, for instance, the degeneracy energy into fluid kinetic energy. Such states may be of relevance to compact astrophysical objects like white dwarfs, neutron stars, etc.

  12. Electron Heating in Microwave-Assisted Helicon Plasmas

    NASA Astrophysics Data System (ADS)

    McKee, John; Siddiqui, Umair; Jemiolo, Andrew; McIlvain, Julianne; Scime, Earl

    2016-10-01

    The use of two (or more) rf sources at different frequencies is a common technique in the plasma processing industry to control ion energy characteristics separately from plasma generation. A similar approach is presented here with the focus on modifying the electron population in argon and helium plasmas. The plasma is generated by a helicon source at a frequency f 0 = 13.56 MHz. Mcrowaves of frequency f 1 = 2.45 GHz are then injected into the helicon source chamber perpendicular to the background magnetic field. The microwaves damp on the electrons via X-mode Electron Cyclotron Heating (ECH) at the upper hybrid resonance, providing additional energy input into the electrons. The effects of this secondary-source heating on electron density, temperature, and energy distribution function are examined and compared to helicon-only single source plasmas as well as numeric models suggesting that the heating is not evenly distributed but spatially localized. Optical Emission Spectroscopy (OES) is used to examine the impact of the energetic tail of the electron distribution on ion and neutral species via collisional excitation. Large enhancements of neutral spectral lines are observed with little to no enhancement of ion lines.

  13. Radiation from High Temperature Plasmas.

    DTIC Science & Technology

    1980-09-09

    PERFORMING ORGANIZATION NAME AND ADDRESS IO7PUOAM i. .’- "--"--o TASK AREA & WORK UNIT NUMIERS SI I. CONTROLLING OFFICE NAME AND ADDRESS .... D...8217’ -REPORT OATM September 19 14. MONITOING AGENCY NAME & AOORESS(I! dilfl ,rn lm Controlling Office) IS. SECURITY CLASS. (of tli repot) Unclassified 1S...together (specifically 25-50 X, in aluminum) id show comparable intensities is an indicatiou oE a rather substantial temperatura aradient in the plasma

  14. Principle of radial transport in low temperature annular plasmas

    SciTech Connect

    Zhang, Yunchao Charles, Christine; Boswell, Rod

    2015-07-15

    Radial transport in low temperature annular plasmas is investigated theoretically in this paper. The electrons are assumed to be in quasi-equilibrium due to their high temperature and light inertial mass. The ions are not in equilibrium and their transport is analyzed in three different situations: a low electric field (LEF) model, an intermediate electric field (IEF) model, and a high electric field (HEF) model. The universal IEF model smoothly connects the LEF and HEF models at their respective electric field strength limits and gives more accurate results of the ion mobility coefficient and effective ion temperature over the entire electric field strength range. Annular modelling is applied to an argon plasma and numerical results of the density peak position, the annular boundary loss coefficient and the electron temperature are given as functions of the annular geometry ratio and Paschen number.

  15. Principle of radial transport in low temperature annular plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2015-07-01

    Radial transport in low temperature annular plasmas is investigated theoretically in this paper. The electrons are assumed to be in quasi-equilibrium due to their high temperature and light inertial mass. The ions are not in equilibrium and their transport is analyzed in three different situations: a low electric field (LEF) model, an intermediate electric field (IEF) model, and a high electric field (HEF) model. The universal IEF model smoothly connects the LEF and HEF models at their respective electric field strength limits and gives more accurate results of the ion mobility coefficient and effective ion temperature over the entire electric field strength range. Annular modelling is applied to an argon plasma and numerical results of the density peak position, the annular boundary loss coefficient and the electron temperature are given as functions of the annular geometry ratio and Paschen number.

  16. Electron acoustic solitary waves in a magnetized plasma with nonthermal electrons and an electron beam

    SciTech Connect

    Singh, S. V. Lakhina, G. S.; Devanandhan, S.; Bharuthram, R.

    2016-08-15

    A theoretical investigation is carried out to study the obliquely propagating electron acoustic solitary waves having nonthermal hot electrons, cold and beam electrons, and ions in a magnetized plasma. We have employed reductive perturbation theory to derive the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation describing the nonlinear evolution of these waves. The two-dimensional plane wave solution of KdV-ZK equation is analyzed to study the effects of nonthermal and beam electrons on the characteristics of the solitons. Theoretical results predict negative potential solitary structures. We emphasize that the inclusion of finite temperature effects reduces the soliton amplitudes and the width of the solitons increases by an increase in the obliquity of the wave propagation. The numerical analysis is presented for the parameters corresponding to the observations of “burst a” event by Viking satellite on the auroral field lines.

  17. Electron acoustic solitary waves in a magnetized plasma with nonthermal electrons and an electron beam

    NASA Astrophysics Data System (ADS)

    Singh, S. V.; Devanandhan, S.; Lakhina, G. S.; Bharuthram, R.

    2016-08-01

    A theoretical investigation is carried out to study the obliquely propagating electron acoustic solitary waves having nonthermal hot electrons, cold and beam electrons, and ions in a magnetized plasma. We have employed reductive perturbation theory to derive the Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation describing the nonlinear evolution of these waves. The two-dimensional plane wave solution of KdV-ZK equation is analyzed to study the effects of nonthermal and beam electrons on the characteristics of the solitons. Theoretical results predict negative potential solitary structures. We emphasize that the inclusion of finite temperature effects reduces the soliton amplitudes and the width of the solitons increases by an increase in the obliquity of the wave propagation. The numerical analysis is presented for the parameters corresponding to the observations of "burst a" event by Viking satellite on the auroral field lines.

  18. A new electron temperature diagnostic of critical surface based on the ion acoustic decay instability in hot, high density plasma relevant to laser fusion. Semiannual report, April 1--September 29, 1994

    SciTech Connect

    Mizuno, K.; DeGroot, J.S.; Drake, R.P.; Seka, W.; Craxton, R.S.; Estabrook, K.G.

    1994-12-31

    The authors made analysis of the IADI experiments previously made using OMEGA laser system. They obtained two important new results: the first direct observation of the epw excited by the Ion Acoustic Decay Instability, and the first study of the IADI in a plasma that approaches laser-fusion conditions, in the sense of having a density scale length of order 1 mm and an electron temperature, T{sub e}, in excess of 1 keV. Previous observations of the epw`s have been based on the second harmonic emission, from which little can be inferred because the emission is produced by unknown pairs of epw`s, integrated in a complicated way over wavenumber space and real space. In contrast, they have directly observed the epw by using the 90{degree}, collective Thomson scattering (CTS) of a UV laser (at the third harmonic of the pump) from the epw`s. Because the ratio of probe frequency to electron plasma frequency is only about three, the scattering is collective (i.e. k{sub epw}{lambda}{sub De} is small, where k{sub epw} is the epw wave number and {lambda}{sub De} is the Debye length),m even though the scattering angle is large. The electron temperature can then be deduced from the ion sound velocity, obtained from the measurement of the frequency at which growth is maximum at the scattering wavenumber.

  19. Electron--positron beam--plasma experiments

    NASA Astrophysics Data System (ADS)

    Gilbert, S. J.; Kurz, C. K.; Greaves, R. G.; Surko, C. M.

    1997-11-01

    Electron-positron plasmas possess unique properties due to inherent symmetries between the charge species. The ability to accumulate large numbers of cold positrons in Penning-Malmberg traps has made the study of such plasmas possible in the laboratory.(R.G. Greaves, M.D. Tinkle and C.M. Surko, Phys. Plas.) 1 1439 (1994) In the first experiment of this type we studied a beam-plasma system by transmitting an electron beam through a positron plasma in a Penning trap.(R.G. Greaves and C.M. Surko, Phys. Rev. Lett.), 74 3846 (1995) These earlier measurements were obtained using a hot cathode electron source, for which the large beam energy spreads ( ~ 0.5 eV) made it impossible to explore the low energy regime of this beam-plasma system, where the strongest interaction occurs. We report new growth rate measurements obtained using a novel low-energy, cold (Δ E ≈ 0.05 eV) electron beam based on the extraction of electrons stored in a Penning trap.(S.J. Gilbert et al.), Appl. Phys. Lett., 70 1944 (1997). The measured growth rates for a transit time instability are found to be in excellent agreement with a cold fluid theory by D.H.E. Dubin over the range of accessible energies (0.1--3 eV).

  20. Plasma properties in electron-bombardment ion thrusters

    NASA Technical Reports Server (NTRS)

    Matossian, J. N.; Beattie, J. R.

    1987-01-01

    The paper describes a technique for computing volume-averaged plasma properties within electron-bombardment ion thrusters, using spatially varying Langmuir-probe measurements. Average values of the electron densities are defined by integrating the spatially varying Maxwellian and primary electron densities over the ionization volume, and then dividing by the volume. Plasma properties obtained in the 30-cm-diameter J-series and ring-cusp thrusters are analyzed by the volume-averaging technique. The superior performance exhibited by the ring-cusp thruster is correlated with a higher average Maxwellian electron temperature. The ring-cusp thruster maintains the same fraction of primary electrons as does the J-series thruster, but at a much lower ion production cost. The volume-averaged predictions for both thrusters are compared with those of a detailed thruster performance model.

  1. Ideal Laser Beam Propagation through high temperature ignition hohlraum plasmas

    SciTech Connect

    Froula, D H; Divol, L; Meezan, N; Dixit, S; Moody, J D; Pollock, B B; Ross, J S; Glenzer, S H

    2006-09-20

    We demonstrate that a blue (3{omega}, 351 nm) laser beam with an intensity of 2 x 10{sup 15} W-cm{sup -2} propagates within the original beam cone through a 2-mm long, T{sub e}=3.5 keV high density (n{sub e} = 5 x 10{sup 20} cm{sup -3}) plasma. The beam produced less than 1% total backscatter; the resulting transmission is greater than 90%. Scaling of the electron temperature in the plasma shows that the plasma becomes transparent for uniform electron temperatures above 3 keV. These results are consistent with linear theory thresholds for both filamentation and backscatter instabilities inferred from detailed hydrodynamic simulations. This provides a strong justification for current inertial confinement fusion designs to remain below these thresholds.

  2. A simple and straightforward expression for curling probe electron density diagnosis in reactive plasmas

    NASA Astrophysics Data System (ADS)

    Arshadi, Ali; Brinkmann, Ralf Peter; Hotta, Masaya; Nakamura, Keiji

    2017-04-01

    Active plasma resonance spectroscopy (APRS) refers to the family of plasma diagnostic methods which utilize the ability of plasmas to resonate at frequencies close to the plasma frequency. APRS operates by exciting the plasma with a weak RF signal by means of a small electric probe. The response of the plasma is recorded by a network analyzer (NA). A mathematical model is applied to derive characteristics like the electron density and the electron temperature. The curling probe is a promising realization of APRS. The curling probe is well-qualified for the local measurement of the electron density in reactive plasmas. This spiral probe resonates in plasma at a larger density dependent frequency than the plasma frequency. This manuscript represents a simple and straightforward expression relating this resonance frequency to the electron density of the plasma. A good agreement is observed between the proposed expression and the results obtained from previous studies and numerical simulations.

  3. Runaway electron generation in a cooling plasma

    SciTech Connect

    Smith, H.; Helander, P.; Eriksson, L.-G.; Fueloep, T.

    2005-12-15

    The usual calculation of Dreicer [Phys. Rev. 115, 238 (1959); 117, 329 (1960)] generation of runaway electrons assumes that the plasma is in a steady state. In a tokamak disruption this is not necessarily true since the plasma cools down quickly and the collision time for electrons at the runaway threshold energy can be comparable to the cooling time. The electron distribution function then acquires a high-energy tail which can easily be converted to a burst of runaways by the rising electric field. This process is investigated and simple criteria for its importance are derived. If no rapid losses of fast electrons occur, this can be a more important source of runaway electrons than ordinary Dreicer generation in tokamak disruptions.

  4. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    SciTech Connect

    Lunov, O. Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A.; Deyneka, I. G.; Meshkovskii, I. K.; Syková, E.; Kubinová, Š.

    2015-02-02

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

  5. Influence of emitter temperature on the energy deposition in a low-pressure plasma

    SciTech Connect

    Levko, Dmitry; Raja, Laxminarayan L.

    2016-03-15

    The influence of emitter temperature on the energy deposition into low-pressure plasma is studied by the self-consistent one-dimensional Particle-in-Cell Monte Carlo Collisions model. Depending on the emitter temperature, different modes of discharge operation are obtained. The mode type depends on the plasma frequency and does not depend on the ratio between the densities of beam and plasma electrons. Namely, plasma is stable when the plasma frequency is small. For this plasma, the energy transfer from emitted electrons to plasma electrons is inefficient. The increase in the plasma frequency results first in the excitation of two-stream electron instability. However, since the thermal velocity of plasma electrons is smaller than the electrostatic wave velocity, the resonant wave-particle interaction is inefficient for the energy deposition into the plasma. Further increase in the plasma frequency leads to the distortion of beam of emitted electrons. Then, the electrostatic wave generated due to two-stream instability decays into multiple slower waves. Phase velocities of these waves are comparable with the thermal velocity of plasma electrons which makes possible the resonant wave-particle interaction. This results in the efficient energy deposition from emitted electrons into the plasma.

  6. Characteristics of surface sterilization using electron cyclotron resonance plasma

    NASA Astrophysics Data System (ADS)

    Yonesu, Akira; Hara, Kazufumi; Nishikawa, Tatsuya; Hayashi, Nobuya

    2016-07-01

    The characteristics of surface sterilization using electron cyclotron resonance (ECR) plasma were investigated. High-energy electrons and oxygen radicals were observed in the ECR zone using electric probe and optical emission spectroscopic methods. A biological indicator (BI), Geobacillus stearothermophilus, containing 1 × 106 spores was sterilized in 120 s by exposure to oxygen discharges while maintaining a temperature of approximately 55 °C at the BI installation position. Oxygen radicals and high-energy electrons were found to be the sterilizing species in the ECR region. It was demonstrated that the ECR plasma could be produced in narrow tubes with an inner diameter of 5 mm. Moreover, sterilization tests confirmed that the spores present inside the narrow tube were successfully inactivated by ECR plasma irradiation.

  7. Tamm states in electron plasma

    NASA Astrophysics Data System (ADS)

    2013-11-01

    Researchers have fabricated a voltage-tunable plasmonic crystal in a two-dimensional electron gas that operates at terahertz frequencies. Nature Photonics spoke to Eric Shaner, Greg Dyer and Greg Aizin about the observation of Tamm states at the crystal's edge.

  8. Electronic transport in partially ionized water plasmas

    NASA Astrophysics Data System (ADS)

    French, Martin; Redmer, Ronald

    2017-09-01

    We use ab initio simulations based on density functional theory to calculate the electrical and thermal conductivities of electrons in partially ionized water plasmas at densities above 0.1 g/cm3. The resulting conductivity data are then fitted to analytic expressions for convenient application. For low densities, we develop a simple and fully analytic model for electronic transport in low-density plasmas in the chemical picture using the relaxation-time approximation. In doing so, we derive a useful analytic expression for electronic transport cross sections with neutral particles, based on a model potential. In the regime of thermal ionization, electrical conductivities from the analytic model agree with the ab initio data within a factor of 2. Larger deviations are observed for the thermal conductivity, and their origin is discussed. Our results are relevant for modeling the interior and evolution of water-rich planets as well as for technical plasma applications.

  9. Electron vortex magnetic holes: A nonlinear coherent plasma structure

    SciTech Connect

    Haynes, Christopher T. Burgess, David; Sundberg, Torbjorn; Camporeale, Enrico

    2015-01-15

    We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.

  10. Electron vortex magnetic holes: A nonlinear coherent plasma structure

    NASA Astrophysics Data System (ADS)

    Haynes, Christopher T.; Burgess, David; Camporeale, Enrico; Sundberg, Torbjorn

    2015-01-01

    We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.

  11. Electron density and electron temperature measurements in nanosecond pulse discharges over liquid water surface

    NASA Astrophysics Data System (ADS)

    Simeni Simeni, M.; Roettgen, A.; Petrishchev, V.; Frederickson, K.; Adamovich, I. V.

    2016-12-01

    Time-resolved electron density, electron temperature, and gas temperature in nanosecond pulse discharges in helium and O2-He mixtures near liquid water surface are measured using Thomson/pure rotational Raman scattering, in two different geometries, (a) ‘diffuse filament’ discharge between a spherical high-voltage electrode and a grounded pin electrode placed in a reservoir filled with distilled water, with the tip exposed, and (b) dielectric barrier discharge between the high-voltage electrode and the liquid water surface. A diffuse plasma filament generated between the electrodes in helium during the primary discharge pulse exhibits noticeable constriction during the secondary discharge pulse several hundred ns later. Adding oxygen to the mixture reduces the plasma filament diameter and enhances constriction during the secondary pulse. In the dielectric barrier discharge, diffuse volumetric plasma occupies nearly the entire space between the high voltage electrode and the liquid surface, and extends radially along the surface. In the filament discharge in helium, adding water to the container results in considerable reduction of plasma lifetime compared to the discharge in dry helium, by about an order of magnitude, indicating rapid electron recombination with water cluster ions. Peak electron density during the pulse is also reduced, by about a factor of two, likely due to dissociative attachment to water vapor during the discharge pulse. These trends become more pronounced as oxygen is added to the mixture, which increases net rate of dissociative attachment. Gas temperature during the primary discharge pulse remains near room temperature, after which it increases up to T ~ 500 K over 5 µs and decays back to near room temperature before the next discharge pulse several tens of ms later. As expected, electron density and electron temperature in diffuse DBD plasmas are considerably lower compared to peak values in the filament discharge. Use of Thomson

  12. A predictive model for the temperature relaxation rate in dense plasmas

    SciTech Connect

    Daligault, Jerome; Dimonte, Guy

    2008-01-01

    We present and validate a simple model for the electron-ion temperature relaxation rate in plasmas that applies over a wide range of plasma temperatures and densities, including weakly-coupled, non-degenerate as well as strongly-coupled, degenerate plasmas. Electron degeneracy and static correlation effects between electrons and ions are shown to play a cumulative role that, at low temperature, lead to relaxation rates a few times smaller than when these effects are neglected. We predict the evolution of the relaxation in dense hydrogen plasmas from the fully degenerate to the non-degenerate limit.

  13. Formation of High-Beta Plasma and Stable Confinement of Toroidal Electron Plasma in RT-1

    NASA Astrophysics Data System (ADS)

    Saitoh, Haruhiko

    2010-11-01

    The Ring Trap 1 (RT-1) device is a laboratory magnetosphere generated by a levitated superconducting magnet. The goals of RT-1 are to realize stable formation of ultra high-beta plasma suitable for burning advanced fusion fuels, and confinement of toroidal non-neutral plasmas including antimatter particles. RT- 1 has produced high-beta plasma in the magnetospheric configuration. The effects of coil levitation and geomagnetic field compensation [Y. Yano et al., Plasma Fusion Res. 4, 039] resulted drastic improvements of the plasma properties, and a maximum local beta value exceeded 70%. Because plasma is generated by electron cyclotron resonance heating (ECH) in the present experiment, the plasma pressure is mainly due to hot electrons, whose bremsstrahlung was observed with an x-ray CCD camera. The pressure profiles have rather steep gradient near the superconducting coil in the strong field region. The decay rates of magnetic probe and interferometer signals have different time constants, suggesting multiple temperature components. The energy confinement time estimated from the input RF power and stored magnetic energy is on the order of 1s, which is comparable to the decay time constant of the density of hot electron component. Pure electron plasma experiments are also conducted in RT-1. Radial profiles of electrostatic potential and electron density showed that the plasma rigidly rotates in the toroidal direction in the stable confinement phase. Long time confinement of toroidal non- neutral plasma for more than 300s and inward particle diffusion to strong field regions, caused by the activation of the diocotron (Kelvin-Helmholtz) instability, have been realized [Z. Yoshida et al., Phys. Rev. Lett. 104, 235004].

  14. Influence of electron injection into 27 cm audio plasma cell on the plasma diagnostics

    SciTech Connect

    Haleem, N. A.; Ragheb, M. S.; Zakhary, S. G.; El Fiki, S. A.; Nouh, S. A.; El Disoki, T. M.

    2013-08-15

    In this article, the plasma is created in a Pyrex tube (L = 27 cm, φ= 4 cm) as a single cell, by a capacitive audio frequency (AF) discharge (f = 10–100 kHz), at a definite pressure of ∼0.2 Torr. A couple of tube linear and deviating arrangements show plasma characteristic conformity. The applied AF plasma and the injection of electrons into two gas mediums Ar and N{sub 2} revealed the increase of electron density at distinct tube regions by one order to attain 10{sup 13}/cm{sup 3}. The electrons temperature and density strengths are in contrast to each other. While their distributions differ along the plasma tube length, they show a decaying sinusoidal shape where their peaks position varies by the gas type. The electrons injection moderates electron temperature and expands their density. The later highest peak holds for the N{sub 2} gas, at electrons injection it changes to hold for the Ar. The sinusoidal decaying density behavior generates electric fields depending on the gas used and independent of tube geometry. The effect of the injected electrons performs a responsive impact on electrons density not attributed to the gas discharge. Analytical tools investigate the interaction of the plasma, the discharge current, and the gas used on the electrodes. It points to the emigration of atoms from each one but for greater majority they behave to a preferred direction. Meanwhile, only in the linear regime, small percentage of atoms still moves in reverse direction. Traces of gas atoms revealed on both electrodes due to sheath regions denote lack of their participation in the discharge current. In addition, atoms travel from one electrode to the other by overcoming the sheaths regions occurring transportation of particles agglomeration from one electrode to the other. The electrons injection has contributed to increase the plasma electron density peaks. These electrons populations have raised the generated electrostatic fields assisting the elemental ions

  15. Relativistic thermal electron scale instabilities in sheared flow plasma

    NASA Astrophysics Data System (ADS)

    Miller, Evan D.; Rogers, Barrett N.

    2016-04-01

    > The linear dispersion relation obeyed by finite-temperature, non-magnetized, relativistic two-fluid plasmas is presented, in the special case of a discontinuous bulk velocity profile and parallel wave vectors. It is found that such flows become universally unstable at the collisionless electron skin-depth scale. Further analyses are performed in the limits of either free-streaming ions or ultra-hot plasmas. In these limits, the system is highly unstable in the parameter regimes associated with either the electron scale Kelvin-Helmholtz instability (ESKHI) or the relativistic electron scale sheared flow instability (RESI) recently highlighted by Gruzinov. Coupling between these modes provides further instability throughout the remaining parameter space, provided both shear flow and temperature are finite. An explicit parameter space bound on the highly unstable region is found.

  16. Launched electrons in plasma opening switches

    NASA Astrophysics Data System (ADS)

    Mendel, C. W., Jr.; Rochau, G. E.; Sweeney, M. A.; McDaniel, D. H.; Quintenz, J. P.; Savage, M. E.; Lindman, E. L.; Kindel, J. M.

    Plasma opening switches have provided a means to improve the characteristics of super-power pulse generators. Recent advances involving plasma control with fast and slow magnetic fields have made these switches more versatile, allowing for improved switch uniformity, triggering, and opening current levels that are set by the level of auxiliary fields. Such switches necessarily involve breaks in the translational symmetry of the transmission line geometry and therefore affect the electron flow characteristics of the line. These symmetry breaks are the result of high electric field regions caused by plasma conductors remaining in the transmission line, ion beams crossing the line, or auxilliary magnetic field regions. Symmetry breaks cause the canonical momentum of the electrons to change, thereby moving them away from the cathode. Additional electrons are pulled from the cathode into the magnetically insulated flow, resulting in an excess of electron flow over that expected for the voltage and line current downstream of the switch. These electrons are called launched electrons. Unless they are recaptured at the cathode or else are fed into the load and used beneficially, they cause a large power loss downstream. Examples are shown of SuperMite and PBFA II data showing these losses, the tools used to study them are explained, and the mechanisms employed to mitigate the problem are discussed. The losses will be reduced primarily by reducing the amount of launched electron flow.

  17. Ion-acoustic instability of a two-temperature, collisional, fully-ionized plasma.

    NASA Technical Reports Server (NTRS)

    Rognlien, T. D.; Self, S. A.

    1971-01-01

    From a perturbation analysis of the fluid equations for a homogeneous unmagnetized plasma, it is shown that long wavelength ion waves are unstable when the electron temperature exceeds the ion temperature. Thus, the temperature difference can drive a resistive-type ion wave instability in a plasma which on a collisionless basis is stable. The additional destabilizing effect of a current is also investigated.

  18. Stability of shock waves in high temperature plasmas

    SciTech Connect

    Das, Madhusmita; Bhattacharya, Chandrani; Menon, S. V. G.

    2011-10-15

    The Dyakov-Kontorovich criteria for spontaneous emission of acoustic waves behind shock fronts are investigated for high temperature aluminum and beryllium plasmas. To this end, the Dyakov and critical stability parameters are calculated from Rankine-Hugoniot curves using a more realistic equation of state (EOS). The cold and ionic contributions to the EOS are obtained via scaled binding energy and mean field theory, respectively. A screened hydrogenic model, including l-splitting, is used to calculate the bound electron contribution to the electronic EOS. The free electron EOS is obtained from Fermi-Dirac statistics. Predictions of the model for ionization curves and shock Hugoniot are found to be in excellent agreement with available experimental and theoretical data. It is observed that the electronic EOS has significant effect on the stability of the planar shock front. While the shock is stable for low temperatures and pressures, instability sets in as temperature rises. The basic reason is ionization of electronic shells and consequent increase in electronic specific heat. The temperatures and densities of the unstable region correspond to those where electronic shells get ionized. With the correct modeling of bound electrons, we find that shock instability for Al occurs at a compression ratio {approx}5.4, contrary to the value {approx}3 reported in the literature. Free electrons generated in the ionization process carry energy from the shock front, thereby giving rise to spontaneously emitted waves, which decay the shock front.

  19. 100 eV electron temperatures in the Maryland centrifugal experiment observed using electron Bernstein emission

    SciTech Connect

    Reid, R. R.; Romero-Talamás, C. A.; Young, W. C.; Ellis, R. F.; Hassam, A. B.

    2014-06-15

    Thermal electron Bernstein emission has been observed at the second harmonic of the electron cyclotron frequency at the mid-plane of the Maryland Centrifugal eXperiment. The emission is received in the X-mode polarization and coupled to the Bernstein wave by the B-X mode conversion process. The average B-X coupling efficiency is approximately 20%. The observed emission indicates thermal electron temperatures an excess of 100 eV in the core of the rotating plasma. The measured electron temperature is consistent with recent ion temperature measurements and indicates that the total energy confinement time exceeds 500 μs.

  20. Electron temperatures and densities in the venus ionosphere: pioneer venus orbiter electron temperature probe results.

    PubMed

    Brace, L H; Theis, R F; Krehbiel, J P; Nagy, A F; Donahue, T M; McElroy, M B; Pedersen, A

    1979-02-23

    Altitude profiles of electron temperature and density in the ionosphere of Venus have been obtained by the Pioneer Venus orbiter electron temperatutre probe. Elevated temperatutres observed at times of low solar wind flux exhibit height profiles that are consistent with a model in which less than 5 percent of the solar wind energy is deposited at the ionopause and is conducted downward through an unmagnetized ionosphere to the region below 200 kilomneters where electron cooling to the neutral atmosphere proceeds rapidly. When solar wind fluxes are higher, the electron temperatures and densities are highly structured and the ionopause moves to lower altitudes. The ionopause height in the late afternoon sector observed thus far varies so widely from day to (day that any height variation with solar zenith angle is not apparent in the observations. In the neighborhood of the ionopause, measuremnents of plasma temperatures and densities and magnetic field strength indicate that an induced magnetic barrier plays an important role in the pressure transfer between the solar wind and the ionosphere. The bow, shock is marked by a distinct increase in electron current collected by the instrument, a featutre that provides a convenient identification of the bow shock location.

  1. Measurements of Plasma Expansion due to Background Gas in the Electron Diffusion Gauge Experiment

    SciTech Connect

    Kyle A. Morrison; Stephen F. Paul; Ronald C. Davidson

    2003-08-11

    The expansion of pure electron plasmas due to collisions with background neutral gas atoms in the Electron Diffusion Gauge (EDG) experiment device is observed. Measurements of plasma expansion with the new, phosphor-screen density diagnostic suggest that the expansion rates measured previously were observed during the plasma's relaxation to quasi-thermal-equilibrium, making it even more remarkable that they scale classically with pressure. Measurements of the on-axis, parallel plasma temperature evolution support the conclusion.

  2. Controlled thermonuclear fusion, high temperature plasma physics

    NASA Astrophysics Data System (ADS)

    1985-05-01

    The primary source of nuclear energy comes from the fission process of heavy nuclei. To utilize the energy released by a thermonuclear fusion process, methods of controlling the fusion reaction were studied. This is controlled thermonuclear fusion technology. The fuel used in a thermonuclear fusion process are isotopes of hydrogen: deuterium and tritium. They can be extracted from the almost unlimited seawater. Nuclear fusion also produces very little radioactive waste. Thermonuclear fusion is a promising energy source with an almost unlimited supply; it is economical, safe, and relatively clean. Ways to raise plasma temperature to a very high level and to maintain it to allow fusion reactions to take place are studied. The physical laws of high temperature plasma was studied to reach this goal which resulted in the development of high temperature plasma physics.

  3. Plasma-Catalysis During Temperature Transient Testing

    SciTech Connect

    Hoard, John

    2001-08-05

    A combination of catalysts is used together with nonthermal plasma in simulated diesel exhaust, while the gas temperature is varied. The catalysts both store and convert pollutants. As a result, pollutant concentrations during temperature ramps are different than those at steady state conditions. The data are presented for plasma followed by BaY, alumina, and Pt catalysts in simulated exhaust. When temperature ramps from high to low, apparent NOx conversion is quite high. However, when temperature is ramped from low to high, lower apparent conversions are seen. In a typical test cycle, average NOx conversion between 100 and 400 C is 60%. Peak conversion during the down ramp is over 90%, and minimum conversion during the up ramp is 30%. The composition of the effluent gas also varies during the temperature cycle. Intermediates such as methyl nitrate and hydrogen cyanide are not present following the combination of catalysts.

  4. Numerical Simulation of the Self-Heating Effect Induced by Electron Beam Plasma in Atmosphere

    NASA Astrophysics Data System (ADS)

    Deng, Yongfeng; Tan, Chang; Han, Xianwei; Tan, Yonghua

    2012-02-01

    For exploiting advantages of electron beam air plasma in some unusual applications, a Monte Carlo (MC) model coupled with heat transfer model is established to simulate the characteristics of electron beam air plasma by considering the self-heating effect. Based on the model, the electron beam induced temperature field and the related plasma properties are investigated. The results indicate that a nonuniform temperature field is formed in the electron beam plasma region and the average temperature is of the order of 600 K. Moreover, much larger volume pear-shaped electron beam plasma is produced in hot state rather than in cold state. The beam ranges can, with beam energies of 75 keV and 80 keV, exceed 1.0 m and 1.2 m in air at pressure of 100 torr, respectively. Finally, a well verified formula is obtained for calculating the range of high energy electron beam in atmosphere.

  5. Twisted electron-acoustic waves in plasmas

    NASA Astrophysics Data System (ADS)

    Aman-ur-Rehman, Ali, S.; Khan, S. A.; Shahzad, K.

    2016-08-01

    In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number qeff accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping rate of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.

  6. Nonquasineutral electron vortices in nonuniform plasmas

    SciTech Connect

    Angus, J. R.; Richardson, A. S.; Swanekamp, S. B.; Schumer, J. W.; Ottinger, P. F.

    2014-11-15

    Electron vortices are observed in the numerical simulation of current carrying plasmas on fast time scales where the ion motion can be ignored. In plasmas with nonuniform density n, vortices drift in the B × ∇n direction with a speed that is on the order of the Hall speed. This provides a mechanism for magnetic field penetration into a plasma. Here, we consider strong vortices with rotation speeds V{sub ϕ} close to the speed of light c where the vortex size δ is on the order of the magnetic Debye length λ{sub B}=|B|/4πen and the vortex is thus nonquasineutral. Drifting vortices are typically studied using the electron magnetohydrodynamic model (EMHD), which ignores the displacement current and assumes quasineutrality. However, these assumptions are not strictly valid for drifting vortices when δ ≈ λ{sub B}. In this paper, 2D electron vortices in nonuniform plasmas are studied for the first time using a fully electromagnetic, collisionless fluid code. Relatively large amplitude oscillations with periods that correspond to high frequency extraordinary modes are observed in the average drift speed. The drift speed W is calculated by averaging the electron velocity field over the vorticity. Interestingly, the time-averaged W from these simulations matches very well with W from the much simpler EMHD simulations even for strong vortices with order unity charge density separation.

  7. Nonquasineutral electron vortices in nonuniform plasmas

    NASA Astrophysics Data System (ADS)

    Angus, J. R.; Richardson, A. S.; Ottinger, P. F.; Swanekamp, S. B.; Schumer, J. W.

    2014-11-01

    Electron vortices are observed in the numerical simulation of current carrying plasmas on fast time scales where the ion motion can be ignored. In plasmas with nonuniform density n, vortices drift in the B × ∇n direction with a speed that is on the order of the Hall speed. This provides a mechanism for magnetic field penetration into a plasma. Here, we consider strong vortices with rotation speeds Vϕ close to the speed of light c where the vortex size δ is on the order of the magnetic Debye length λB=|B |/4 πe n and the vortex is thus nonquasineutral. Drifting vortices are typically studied using the electron magnetohydrodynamic model (EMHD), which ignores the displacement current and assumes quasineutrality. However, these assumptions are not strictly valid for drifting vortices when δ ≈ λB. In this paper, 2D electron vortices in nonuniform plasmas are studied for the first time using a fully electromagnetic, collisionless fluid code. Relatively large amplitude oscillations with periods that correspond to high frequency extraordinary modes are observed in the average drift speed. The drift speed W is calculated by averaging the electron velocity field over the vorticity. Interestingly, the time-averaged W from these simulations matches very well with W from the much simpler EMHD simulations even for strong vortices with order unity charge density separation.

  8. Twisted electron-acoustic waves in plasmas

    SciTech Connect

    Aman-ur-Rehman; Ali, S.; Khan, S. A.; Shahzad, K.

    2016-08-15

    In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number q{sub eff} accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping rate of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.

  9. Analysis of electron transport in the plasma of thermionic converters

    SciTech Connect

    Stoenescu, M.L.; Heinicke, P.H.

    1980-03-01

    Electron transport coefficients of a gaseous ensemble are expressed analytically as function of density, and are expressed analytically as function of temperature up to an unknown function which has to be evaluated for each specific electron-neutral atom cross section. In order to complete the analytical temperature dependence one may introduce a polynomial expansion of the function or one may derive the temperature dependence of a set of coefficients, numbering thirteen for a third approximation transport evaluation, which completely determine the transport coefficients. The latter approach is used for determining the electron transport coefficients of a cesium plasma for any ion neutral composition and any temperature between 500/sup 0/K and 3500/sup 0/K. The relation between the transport coefficients of a fully and partly ionized gas is readily available and shows that, in the classical formalism, electron-ion and electron-neutral resistivities are not additive. The present form of the transport coefficients makes possible an accurate numerical integration of transport equations eliminating lengthy computations which are frequently inaccessible. It thus provides a detailed knowledge of spatial distribution of particle and energy transport and makes possible the determination of one of the three internal voltage drops, surface barrier, sheath and plasma, which are linked together experimentally by current density versus voltage characteristics of thermionic converters.

  10. Application of Nonlocal Electron Kinetics to Plasma Technologies

    NASA Astrophysics Data System (ADS)

    Kaganovich, Igor D.

    2011-10-01

    Partially ionized plasmas are typically in a highly non-equilibrium thermodynamic state: the electrons are not in equilibrium with the neutral particle species or the ions, and the electrons are also not in equilibrium within their own ensemble, which results in a significant departure of the electron velocity distribution function (EVDF) from a Maxwellian. These non-equilibrium conditions provide considerable freedom to choose optimal plasma parameters for applications, which make gas-discharge plasmas remarkable tools for a variety of plasma applications, including plasma processing, discharge lighting, plasma propulsion, particle beam sources, and nanotechnology. Significant progress in understanding the formation of non-Maxwellian EVDF in the self-consistent electric fields has been one of the major achievements in the low-temperature plasmas during the last decade. This progress was made possible by a synergy between full-scale particle-in-cell simulations, analytical models, and experiments. Specific examples include rf discharges, dc discharges with auxiliary electrodes, Hall thruster discharges. In each example, nonlocal kinetic effects are identified as the main mechanisms responsible for the surprising degree of discharge self-organization. These phenomena include: explosive generation of cold electrons with rf power increase in low-pressure rf discharges; abrupt changes in discharge structure with increased bias voltage on a third electrode in a dc discharge with hot cathode; absence of a steady-state regime in Hall thruster discharges with intense secondary electron emission due to coupling of the sheath properties and the EVDF. In collaboration with Y. Raitses, A.V. Khrabrov, M. Campanell, V. I. Demidov, D. Sydorenko, I. Schweigert, and A. S. Mustafaev. Research supported by the U.S. Department of Energy.

  11. Characterization of Secondary Electron Emission Properties of Plasma Facing Materials

    NASA Astrophysics Data System (ADS)

    Patino, Marlene I.; Capece, Angela M.; Raitses, Yevgeny; Koel, Bruce E.

    2015-11-01

    The behavior of wall-bounded plasmas is significantly affected by the plasma-wall interactions, including the emission of secondary electrons (SEE) from the wall materials due to bombardment by primary electrons. The importance of SEE has prompted previous investigations of SEE properties of materials especially with applications to magnetic fusion, plasma thrusters, and high power microwave devices. In this work, we present results of measurements of SEE properties of graphite and lithium materials relevant for the divertor region of magnetic fusion devices. Measurements of total SEE yield (defined as the number of emitted secondary electrons per incident primary electron) for lithium are extended up to 5 keV primary electron energy, and the energy distributions of secondary electrons are provided for graphite and lithium. Additionally, the effect of contamination on the total SEE yield of lithium was explored by exposing the material to water vapor. Auger electron spectroscopy (AES) was used to determine surface composition and temperature programmed desorption (TPD) was used to determine lithium film thickness. Results show an order of magnitude increase in total SEE yield for lithium exposed to water vapor. This work was supported by DOE contract DE-AC02-09CH11466; AFOSR grants FA9550-14-1-0053, FA9550-11-1-0282, and AF9550-09-1-0695; and DOE Office of Science Graduate Student Research Program.

  12. Three-temperature plasma shock solutions with gray radiation diffusion

    NASA Astrophysics Data System (ADS)

    Johnson, B. M.; Klein, R. I.

    2017-03-01

    The effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation. Since the radiation heats the electrons on length scales that are much longer than the electron-ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.

  13. Simultaneous measurement of core electron temperature and density fluctuations during electron cyclotron heating on DIII-D

    SciTech Connect

    White, A. E.; Schmitz, L.; Peebles, W. A.; Rhodes, T. L.; Carter, T. A.; McKee, G. R.; Shafer, M. W.; Staebler, G. M.; Burrell, K. H.; DeBoo, J. C.; Prater, R.

    2010-02-15

    New measurements show that long-wavelength (k{sub t}hetarho{sub s}<0.5) electron temperature fluctuations can play an important role in determining electron thermal transport in low-confinement mode (L-mode) tokamak plasmas. In neutral beam-heated L-mode tokamak plasmas, electron thermal transport and the amplitude of long-wavelength electron temperature fluctuations both increase in cases where local electron cyclotron heating (ECH) is used to modify the plasma profiles. In contrast, the amplitude of simultaneously measured long-wavelength density fluctuations does not significantly increase. Linear stability analysis indicates that the ratio of the trapped electron mode (TEM) to ion temperature gradient (ITG) mode growth rates increases in the cases with ECH. The increased importance of the TEM drive relative to the ITG mode drive in the cases with ECH may be associated with the increases in electron thermal transport and electron temperature fluctuations.

  14. Plasma electron hole kinematics. I. Momentum conservation

    SciTech Connect

    Hutchinson, I. H.; Zhou, C.

    2016-08-15

    We analyse the kinematic properties of a plasma electron hole: a non-linear self-sustained localized positive electric potential perturbation, trapping electrons, which behaves as a coherent entity. When a hole accelerates or grows in depth, ion and electron plasma momentum is changed both within the hole and outside, by an energization process we call jetting. We present a comprehensive analytic calculation of the momentum changes of an isolated general one-dimensional hole. The conservation of the total momentum gives the hole's kinematics, determining its velocity evolution. Our results explain many features of the behavior of hole speed observed in numerical simulations, including self-acceleration at formation, and hole pushing and trapping by ion streams.

  15. Langmuir rogue waves in electron-positron plasmas

    SciTech Connect

    Moslem, W. M.

    2011-03-15

    Progress in understanding the nonlinear Langmuir rogue waves which accompany collisionless electron-positron (e-p) plasmas is presented. The nonlinearity of the system results from the nonlinear coupling between small, but finite, amplitude Langmuir waves and quasistationary density perturbations in an e-p plasma. The nonlinear Schroedinger equation is derived for the Langmuir waves' electric field envelope, accounting for small, but finite, amplitude quasistationary plasma slow motion describing the Langmuir waves' ponderomotive force. Numerical calculations reveal that the rogue structures strongly depend on the electron/positron density and temperature, as well as the group velocity of the envelope wave. The present study might be helpful to understand the excitation of nonlinear rogue pulses in astrophysical environments, such as in active galactic nuclei, in pulsar magnetospheres, in neutron stars, etc.

  16. Electron-positron pair equilibrium in strongly magnetized plasmas

    SciTech Connect

    Harding, A.K.

    1984-11-01

    Steady states of thermal electron-positron pair plasmas at mildly relativistic temperatures and in strong magnetic fields are investigated. The pair density in steady-state equilibrium, where pair production balances annihilation, is found as a function of temperature, magnetic field strength and source size, by a numerical calculation which includes pair production attenuation and Compton scattering of the photons. It is found that there is a maximum pair density for each value of temperature and field strength, and also a source size above which optically thin equilibrium states do not exist. (ESA)

  17. Electron attachment to halomethanes at high temperatures

    NASA Astrophysics Data System (ADS)

    Miller, T. M.; Friedman, J. F.; Schaffer, L. C.; Viggiano, A. A.

    2009-10-01

    We have modified our high-temperature flowing-afterglow apparatus to include a movable Langmuir probe, a 4-needle reactant gas inlet, and a microwave discharge plasma source for the purpose of measuring electron attachment rate constants at high temperatures. We have focused initially on molecules which have very small attachment rate constants, ka, at room temperature to see if their behavior at high temperatures can be described in Arrhenius fashion. We have reported ka for CH3Cl, but only above 600 K, because the value at 600 K was quite small: 5.8 x10-12 cm^3 s-1. The Arrhenius plot for these data imply ka = 10-17 cm^3 s-1 at 300 K, a value that is so small as to be immeasurable with any current apparatus. We now have ka for other halomethanes, CF3Cl, CF2Cl2, and CH2Cl2. The halomethane data cover seven orders-of-magnitude in ka. Electron attachment to CF3Cl is endothermic by 143 meV at 300 K, but our measurements indicate that there is a barrier of about 400 meV, probably related to the energy at which the anion surface crosses that of the neutral. The reactions for CH3Cl, CF2Cl2, and CH2Cl2 are exothermic, but our data again indicate large barriers to attachment which accounts for the extremely slow attachment at 300 K. From these data and literature measurements at 300 K, one can make educated guesses as to the behavior of ka for other halomethanes.

  18. Electron properties and air mixing in radio frequency driven argon plasma jets at atmospheric pressure

    SciTech Connect

    Gessel, Bram van; Bruggeman, Peter; Brandenburg, Ronny

    2013-08-05

    A time modulated radio frequency (RF) plasma jet operated with an Ar mixture is investigated by measuring the electron density and electron temperature using Thomson scattering. The measurements have been performed spatially resolved for two different electrode configurations and as a function of the plasma dissipated power and air concentration admixed to the Ar. Time resolved measurements of electron densities and temperatures during the RF cycle and after plasma power switch-off are presented. Furthermore, the influence of the plasma on the air entrainment into the effluent is studied using Raman scattering.

  19. Spectroscopic diagnostics of high temperature plasmas. [Annual report

    SciTech Connect

    Moos, W.

    1990-12-31

    A three-year research program for the development of novel XUV spectroscopic diagnostics for magnetically confined fusion plasmas is proposed. The new diagnostic system will use layered synthetic microstructures (LSM) coated, flat and curved surfaces as dispersive elements in spectrometers and narrow band XUV filter arrays. In the framework of the proposed program we will develop impurity monitors for poloidal and toroidal resolved measurements on PBX-M and Alcator C-Mod, imaging XUV spectrometers for electron density and temperature fluctuation measurements in the hot plasma core in TEXT or other similar tokamaks and plasma imaging devices in soft x-ray light for impurity behavior studies during RF heating on Phaedrus T and carbon pellet ablation in Alcator C-Mod. Recent results related to use of multilayer in XUV plasma spectroscopy are presented. We also discuss the latest results reviewed to q{sub o} and local poloidal field measurements using Zeeman polarimetry.

  20. Effects of target plasma electron-electron collisions on correlated motion of fragmented protons.

    PubMed

    Barriga-Carrasco, Manuel D

    2006-02-01

    The objective of the present work is to examined the effects of plasma target electron-electron collisions on H2 + protons traversing it. Specifically, the target is deuterium in a plasma state with temperature Te=10 eV and density n=10(23) cm(-3), and proton velocities are vp=vth, vp=2vth, and vp=3vth, where vth is the electron thermal velocity of the target plasma. Proton interactions with plasma electrons are treated by means of the dielectric formalism. The interactions among close protons through plasma electronic medium are called vicinage forces. It is checked that these forces always screen the Coulomb explosions of the two fragmented protons from the same H2 + ion decreasing their relative distance. They also align the interproton vector along the motion direction, and increase the energy loss of the two protons at early dwell times while for longer times the energy loss tends to the value of two isolated protons. Nevertheless, vicinage forces and effects are modified by the target electron collisions. These collisions enhance the calculated self-stopping and vicinage forces over the collisionless results. Regarding proton correlated motion, when these collisions are included, the interproton vector along the motion direction overaligns at slower proton velocities (vp=vth) and misaligns for faster ones (vp=2vth, vp=3vth). They also contribute to a great extend to increase the energy loss of the fragmented H2 + ion. This later effect is more significant in reducing projectile velocity.

  1. Low- and mid- Z EUV spectroscopy of high temperature plasmas

    NASA Astrophysics Data System (ADS)

    Wilcox, Penka Georgieva

    Extreme ultraviolet (EUV) spectroscopy has proven to be an essential tool for plasma diagnostics, both of laboratory and astrophysical plasmas. Exploitation of the EUV and soft x-ray (SXR) spectral regions is very promising but a relatively recent and challenging area of study. While these ranges are more difficult to access, due to the harsh environment and the plentitude of atomic resonances and photoabsorption, they provide very sensitive tools for elemental and chemical identification, thus creating many scientific and technological opportunities. In this dissertation, a comprehensive spectroscopic study of EUV/SXR radiation from variety of low- and mid-Z plasmas was accomplished by the author. The emphasis was on application of the newly developed non-Local Thermodynamics Equilibrium (non-LTE) models of various elements (Li, C, B, N, O, F, Al, and Ni) for studying radiative properties of different high temperature plasmas. In addition, relativistic atomic data calculations, including dielectronic recombination and satellite lines of Ni ions, that implement several different codes and take into account a large number of configurations to assure accuracy, were performed. The applications of models to following experiments were considered: NSTX at Princeton, SSPX and EBIT at LLNL, and "Sparky" laser plasma and NTF Zebra Z-pinch experiments at UNR. As a result, the spectral features of EUV/SRX experimental radiation generated under various plasma conditions were compared and analyzed: from NSTX tokamak (at relatively low electron densities of 1013-1014 cm-3 ) to the laser-produced and Z-pinch plasma spectra (at higher electron densities of 1018-1020 cm-3) and at various electron temperatures -- from as low as 20 eV up to 300 eV. These investigated low- and mid-Z high resolution experimental data help to benchmark and improve our spectroscopic models and theory.

  2. Investigation of the Electronic Structure of Solid Density Plasmas by X-Ray Scattering

    SciTech Connect

    Gregori, G; Glenzer, S H; Forest, F J; Kuhlbrodt, S; Redmer, R; Faussurier, G; Blancard, C; Renaudin, P; Landen, O L

    2003-05-19

    We present an improved analytical expression for the x-ray dynamic structure factor from a dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. We use our theory to interpret x-ray scattering experiments from solid density carbon plasma and to extract accurate measurements of electron temperature, electron density and charge state. We use our experimental results to validate various equation-of-state models for carbon plasmas.

  3. Calculation of electronic transport coefficients of Ag and Au plasma

    SciTech Connect

    Apfelbaum, E. M.

    2011-12-15

    The thermoelectric transport coefficients of silver and gold plasma have been calculated within the relaxation-time approximation. We considered temperatures of 10-100 kK and densities of {rho} < or approx. 1 g/cm{sup 3}. The plasma composition was calculated using a corresponding system of coupled mass action laws, including the atom ionization up to +4. For momentum cross sections of electron-atom scattering we used the most accurate expressions available. The results of our modeling have been compared with other researchers' data whenever possible.

  4. Effect of trapped electrons on soliton propagation in a plasma having a density gradient

    SciTech Connect

    Aziz, Farah; Stroth, Ulrich

    2009-03-15

    A Korteweg-deVries equation with an additional term due to the density gradient is obtained using reductive perturbation technique in an unmagnetized plasma having a density gradient, finite temperature ions, and two-temperature nonisothermal (trapped) electrons. This equation is solved to get the solitary wave solution using sine-cosine method. The phase velocity, soliton amplitude, and width are examined under the effect of electron and ion temperatures and their concentrations. The effect of ion (electron) temperature is found to be more significant in the presence of larger (smaller) number of trapped electrons in the plasma.

  5. EUV induced low temperature SF6-based plasma

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Wachulak, P.; Fiedorowicz, H.; Skrzeczanowski, W.; Jarocki, R.; Fok, T.; Węgrzyński, Ł.

    2016-03-01

    In this work spectral investigations of low temperature F-rich photoionized plasmas were performed. The photoionized plasmas were created by irradiation of SF6 gas with intense EUV (extreme ultraviolet) radiation pulses. Two laser plasma EUV sources of different parameters used in the experiments were based on 0.8 J /4ns and 10 J/ 10 ns Nd:YAG lasers respectively. Both sources operated at 10 Hz repetition rate. The EUV radiation was focused using a dedicated reflective collector onto the gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of the SF6 gas resulted in dissociative ionization of the molecules, leading to creation of SFn+ ions and fluorine atoms. Further photo- or electron impact ionization and excitation processes allow for formation of photoionized plasmas emitting radiation in the wide spectral range. Emission spectra were measured in the EUV and optical ranges. The EUV spectra contained multiple spectral lines, originating from F II, F III and S II ions. The UV/VIS spectra were composed of spectral lines corresponding to radiative transitions in F II, F I and S II species. A computer simulation of the F II spectrum was performed using a collisional-radiative PrismSPECT code. Parameters of the photoionized plasmas were estimated by fitting the spectrum obtained from the simulations to the experimental one. Apart from that, the electron temperature was estimated employing Boltzmann plots based on the UV/VIS spectrum.

  6. Relatively scaled ECE temperature profiles of KSTAR plasmas.

    PubMed

    Choi, M J; Yun, G S; Park, H K; Jeon, Y M; Jeong, S H

    2010-10-01

    A scheme to obtain relatively scaled profiles of electron cyclotron emission (ECE) temperature directly from uncalibrated raw radiometer data is proposed and has been tested for the 2009 campaign KSTAR plasmas. The proposed method utilizes a position controlled system to move the plasma adiabatically and compares ECE radiometer channels at the same relative radial positions assuming the profile consistency during the adiabatic change. This scaling method is an alternative solution when an absolute calibration is unreliable or too time consuming. The application to the two dimensional ECE imaging data, wherein calibration is extremely difficult, may also prove to be useful.

  7. Relatively scaled ECE temperature profiles of KSTAR plasmas

    SciTech Connect

    Choi, M. J.; Yun, G. S.; Park, H. K.; Jeon, Y. M.; Jeong, S. H.

    2010-10-15

    A scheme to obtain relatively scaled profiles of electron cyclotron emission (ECE) temperature directly from uncalibrated raw radiometer data is proposed and has been tested for the 2009 campaign KSTAR plasmas. The proposed method utilizes a position controlled system to move the plasma adiabatically and compares ECE radiometer channels at the same relative radial positions assuming the profile consistency during the adiabatic change. This scaling method is an alternative solution when an absolute calibration is unreliable or too time consuming. The application to the two dimensional ECE imaging data, wherein calibration is extremely difficult, may also prove to be useful.

  8. Towards laboratory produced relativistic electron-positron pair plasmas

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Meyerhofer, D. D.; Wilks, S. C.; Cauble, R.; Dollar, F.; Falk, K.; Gregori, G.; Hazi, A.; Moses, E. I.; Murphy, C. D.; Myatt, J.; Park, J.; Seely, J.; Shepherd, R.; Spitkovsky, A.; Stoeckl, C.; Szabo, C. I.; Tommasini, R.; Zulick, C.; Beiersdorfer, P.

    2011-12-01

    We review recent experimental results on the path to producing electron-positron pair plasmas using lasers. Relativistic pair-plasmas and jets are believed to exist in many astrophysical objects and are often invoked to explain energetic phenomena related to Gamma Ray Bursts and Black Holes. On earth, positrons from radioactive isotopes or accelerators are used extensively at low energies (sub-MeV) in areas related to surface science positron emission tomography and basic antimatter science. Experimental platforms capable of producing the high-temperature pair-plasma and high-flux jets required to simulate astrophysical positron conditions have so far been absent. In the past few years, we performed extensive experiments generating positrons with intense lasers where we found that relativistic electron and positron jets are produced by irradiating a solid gold target with an intense picosecond laser pulse. The positron temperatures in directions parallel and transverse to the beam both exceeded 0.5 MeV, and the density of electrons and positrons in these jets are of order 10 16 cm -3 and 10 13 cm -3, respectively. With the increasing performance of high-energy ultra-short laser pulses, we expect that a high-density, up to 10 18 cm -3, relativistic pair-plasma is achievable, a novel regime of laboratory-produced hot dense matter.

  9. Nonlinear Electron Acoustic Waves in Dissipative Plasma with Superthermal Electrons

    NASA Astrophysics Data System (ADS)

    El-Hanbaly, A. M.; El-Shewy, E. K.; Kassem, A. I.; Darweesh, H. F.

    2016-01-01

    The nonlinear properties of small amplitude electron-acoustic ( EA) solitary and shock waves in a homogeneous system of unmagnetized collisionless plasma consisted of a cold electron fluid and superthermal hot electrons obeying superthermal distribution, and stationary ions have been investigated. A reductive perturbation method was employed to obtain the Kadomstev-Petviashvili-Burgers (KP-Brugers) equation. Some solutions of physical interest are obtained. These solutions are related to soliton, monotonic and oscillatory shock waves and their behaviour are shown graphically. The formation of these solutions depends crucially on the value of the Burgers term and the plasma parameters as well. By using the tangent hyperbolic (tanh) method, another interesting type of solution which is a combination between shock and soliton waves is obtained. The topology of phase portrait and potential diagram of the KP-Brugers equation is investigated.The advantage of using this method is that one can predict different classes of the travelling wave solutions according to different phase orbits. The obtained results may be helpful in better understanding of waves propagation in various space plasma environments as well as in inertial confinement fusion laboratory plasmas.

  10. Superfluorescence from dense electron hole plasmas under high magnetic fields

    NASA Astrophysics Data System (ADS)

    Jho, Y. D.; Wang, X.; Kono, J.; Reitze, D. H.; Wei, X.; Belyanin, A. A.; Kocharovsky, V. V.; Kocharovsky, Vl. V.; Solomon, G. S.

    Ultrafast optical excitation of a dense electron hole plasma in InxGa1-xAs multiple quantum wells in high magnetic fields (>20T) produces cooperative radiative recombination between conduction and valence band Landau levels (LL). Above a critical threshold, the emission is characterized by very narrow LL line widths, superlinear increase with increasing field and laser excitation fluence, and stochastic directionality from shot to shot. Here, we investigate the effects of temperature and excitation geometry on the emission properties.

  11. Ion temperature anisotropies in Venus plasma environment

    NASA Astrophysics Data System (ADS)

    Stenberg Wieser, Gabriella; Bader, Alexander; Futaana, Yoshifumi; Persson, Moa; André, Mats; Nilsson, Hans

    2017-04-01

    The ion velocity distribution is a key to understanding the interplay between ions in the plasma and the waves. Any deviation from a Maxwellian distribution may be unstable and result in wave generation. We use data from ion mass spectrometer IMA (Ion Mass Analyzer) and the magnetometer MAG onboard Venus Express to investigate what unstable ion distributions are found in the plasma environment of Venus. Especially we examine temperature anisotropies, that is, the difference between the ion temperature parallel and perpendicular to the background magnetic field. Scientific questions addressed include: To what extent does such anisotropies occur? Where in the magnetosphere do they occur? What type of waves would we expect them to generate? We produce spatial maps of the average ratio between the perpendicular and parallel temperatures, both for proton and heavy ions (atomic oxygen, molecular oxygen and carbon dioxide).

  12. Improved Magnetic Field Generation Efficiency and Higher Temperature Spheromak Plasmas

    SciTech Connect

    Wood, R D; Hill, D N; McLean, H S; Hooper, E B; Hudson, B F; Moller, J M; Romero-Talamas, C A

    2008-09-15

    New understanding of the mechanisms governing the observed magnetic field generation limits on the sustained spheromak physics experiment has been obtained. Extending the duration of magnetic helicity injection during the formation of a spheromak and optimizing the ratio of injected current to bias flux produce higher magnetic field plasmas with record spheromak electron temperatures. To explore magnetic field buildup efficiency limits, the confinement region geometry was varied resulting in improved field buildup efficiencies.

  13. Three-temperature plasma shock solutions with gray radiation diffusion

    DOE PAGES

    Johnson, Bryan M.; Klein, Richard I.

    2016-04-19

    Here we discuss the effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation.more » Since the radiation heats the electrons on length scales that are much longer than the electron–ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.« less

  14. Three-temperature plasma shock solutions with gray radiation diffusion

    SciTech Connect

    Johnson, Bryan M.; Klein, Richard I.

    2016-04-19

    Here we discuss the effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation. Since the radiation heats the electrons on length scales that are much longer than the electron–ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.

  15. Three-temperature plasma shock solutions with gray radiation diffusion

    SciTech Connect

    Johnson, Bryan M.; Klein, Richard I.

    2016-04-19

    Here we discuss the effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation. Since the radiation heats the electrons on length scales that are much longer than the electron–ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.

  16. Electron-vibration relaxation in oxygen plasmas

    NASA Astrophysics Data System (ADS)

    Laporta, V.; Heritier, K. L.; Panesi, M.

    2016-06-01

    An ideal chemical reactor model is used to study the vibrational relaxation of oxygen molecules in their ground electronic state, X3Σg-, in presence of free electrons. The model accounts for vibrational non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. The vibrational levels of the molecules are treated as separate species, allowing for non-Boltzmann distributions of their population. The electron and vibrational temperatures are varied in the range [0-20,000] K. Numerical results show a fast energy transfer between oxygen molecules and free electron, which causes strong deviation of the vibrational distribution function from Boltzmann distribution, both in heating and cooling conditions. Comparison with Landau-Teller model is considered showing a good agreement for electron temperature range [2000-12,000] K. Finally analytical fit of the vibrational relaxation time is given.

  17. Experimental Investigation of Electron Acoustic Waves in Electron Plasmas.

    NASA Astrophysics Data System (ADS)

    Kabantsev, A. A.; Driscoll, C. F.

    2006-10-01

    Electron-acoustic wave (EAW) solutions of the linearized electrostatic Vlasov equations are usually ignored because their small phase velocity implies a huge linear damping. However, recent nonlinear theory and simulations found that electrons trapped in wave potentials result in long-lived BGK states at the EAW mode frequency. Experimentally, the predicted modes are readily observed on pure electron plasmas, when they are excited by weak wall voltages which are resonant over ˜100 cycles. The modes have phase velocity vφ 1.3 vth, in close agreement with theory; and the long-wavelength BGK states exhibit only weak damping (-γ/ φ<=0.01) due to electron-electron collisions. The mode frequencies are unambiguously calibrated by comparison to electron plasma wave frequencies. Discrete standing modes are observed, but modes with mz= 2,3... show a strong decay instability into mz=1. This instability corresponds to a merger of vortices in (z, vz) phase space, which can be suppressed (or enhanced) by application of potential barriers (or wells) between the high mz wavelengths. J.P. Holloway and J.J. Dorning, Phys. Rev. A. 44 3856 (1991). F. Valentini, T.M. O'Neil, D.H.E. Dubin, Phy Plas 13, 052303 (2006).

  18. Cross-field transport of electrons at the magnetic throat in an annular plasma reactor

    NASA Astrophysics Data System (ADS)

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2017-01-01

    Cross-field transport of electrons has been studied at the magnetic throat of the annular Chi-Kung reactor. This annular configuration allows the creation of a low pressure argon plasma with two distinct electron heating locations by independently operating a radio-frequency antenna surrounding the outer source tube, or an antenna housed inside the inner source tube. The two antenna cases show opposite variation trends in radial profiles of electron energy probability function, electron density, plasma potential and electron temperature. The momentum and energy transport coefficients are obtained from the electron energy probability functions, and the related electron fluxes follow the path of electron cooling across the magnetic throat.

  19. Electron beam generated plasmas for the processing of graphene

    NASA Astrophysics Data System (ADS)

    Walton, S. G.; Hernández, S. C.; Boris, D. R.; Petrova, Tz B.; Petrov, G. M.

    2017-09-01

    The Naval Research Laboratory (NRL) has developed a processing system based on an electron beam-generated plasma and applied it to the processing of graphene. Unlike conventional discharges produced by electric fields (DC, RF, microwave, etc), the plasma is driven by a high-energy (~few keV) electron beam, an approach that simplifies the relative production of species while providing comparatively high ion-to-radical production rates. The resulting plasmas are characterized by high charged particle densities (1010-1011 cm-3) and electron temperatures that are typically about 1.0 eV or lower. Accordingly, the flux to adjacent surfaces is generally dominated by ions with kinetic energies in the range of 1-5 eV, a value at or near the bond strength of most materials. This provides the potential for controllably engineering materials with monolayer precision, an attribute attractive for the processing of atomically thin material systems. This work describes the attributes of electron beam driven plasma processing system and its use in modification of graphene.

  20. Laser-driven electron acceleration in an inhomogeneous plasma channel

    SciTech Connect

    Zhang, Rong; Cheng, Li-Hong; Xue, Ju-Kui

    2015-12-15

    We study the laser-driven electron acceleration in a transversely inhomogeneous plasma channel. We find that, in inhomogeneous plasma channel, the developing of instability for electron acceleration and the electron energy gain can be controlled by adjusting the laser polarization angle and inhomogeneity of plasma channel. That is, we can short the accelerating length and enhance the energy gain in inhomogeneous plasma channel by adjusting the laser polarization angle and inhomogeneity of the plasma channel.

  1. Rotating structures and vortices in low temperature plasmas

    NASA Astrophysics Data System (ADS)

    Boeuf, Jean-Pierre

    2014-10-01

    Rotating structures are present in a number of low temperature EXB devices such as Hall thrusters, magnetrons, Penning discharges etc...Some aspects of the physics of these rotating instabilities are specific to low temperature plasmas because of the relatively large collisionality, the role of ionization, and the fact that ions are often non-magnetized. On the basis of fully kinetic simulations (Particle-In-Cell Monte Carlo Collisions) we describe the formation of a rotating instability associated with an ionization front (``rotating spoke'') and driven by a cross-field current in a self-sustained cylindrical magnetron discharge at gas pressure on the order of 1 Pa. The rotating spoke is a strong double layer (electrostatic sheath) moving towards the higher potential region at a velocity close to the critical ionization velocity, a concept proposed by Alfvén in the context of the formation of the solar system. The mechanisms of cross-field electron transport induced by this instability are analyzed. At lower pressure (<0.01 Pa) the plasma of a magnetron discharge is non-neutral and the simulations predict the formation of electron vortices rotating in the azimuthal direction and resulting from the diocotron instability. The properties of these vortices are specific since they form in a self-sustained discharge where ionization (and losses at the ends of the plasma column) play an essential role in contrast with the electron vortices in pure electron plasmas. We discuss and analyze the mechanisms leading to the generation, dynamics and merging of these self-sustained electron vortices, and to the periodic ejection of fast electrons at the column ends (consistent with previous experimental observations).

  2. Runaway electrons and mitigation studies in MST tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Goetz, J. A.; Chapman, B. E.; Almagri, A. F.; Cornille, B. S.; Dubois, A.; McCollam, K. J.; Munaretto, S.; Sovinec, C. R.

    2016-10-01

    Studies of runaway electrons generated in low-density MST tokamak plasmas are being undertaken. The plasmas have Bt <= 0.14 T, Ip <= 50 kA, q (a) = 2.2 , and an electron density and temperature of about 5 ×1017m-3 and 150 eV. Runaway electrons are detected via x-ray bremsstrahlung emission. The density and electric field thresholds for production and suppression have been previously explored with variations in gas puffing for density control. Runaway electrons are now being probed with resonant magnetic perturbations (RMP's). An m = 3 RMP strongly suppresses the runaway electrons and initial NIMROD modeling shows that this may be due to degradation of flux surfaces. The RMP is produced by a poloidal array of 32 saddle coils at the narrow vertical insulated cut in MST's thick conducting shell, with each RMP having a single m but a broad n spectrum. While a sufficiently strong m = 3 RMP suppresses the runaway electrons, an RMP with m = 1 and comparable amplitude has little effect. The impact of the RMP's on the magnetic topology of these plasmas is being studied with the nonlinear MHD code NIMROD. With an m = 3 RMP, stochasticity is introduced in the outer third of the plasma but no such flux surface degradation is observed with an m = 1 RMP. NIMROD also predicts regularly occurring MHD activity similar to that observed in the experiment. These studies have also been done in q (a) = 2.7 plasmas and analysis and modeling is ongoing. This work supported by USDoE.

  3. Electron temperatures in the Jovian ionosphere

    NASA Technical Reports Server (NTRS)

    Nagy, A. F.; Chameides, W. L.; Chen, R. H.; Atreya, S. K.

    1976-01-01

    The daytime electron temperature profile of the Jovian ionosphere was calculated, taking into account the effects of thermal conduction and heat inflow from the plasmasphere. The photoelectron fluxes and electron heating rates were determined by using the two-stream approach of Banks and Nagy (1970) and Nagy and Banks (1970). The calculated electron temperatures were found to follow the neutral temperature up to an altitude slightly above the electron density peak, while at higher altitudes they were significantly enhanced above the assumed neutral temperature value.

  4. Laser Plasma Coupling for High Temperature Hohlraums

    SciTech Connect

    Kruer, W.

    1999-11-04

    Simple scaling models indicate that quite high radiation temperatures can be achieved in hohlraums driven with the National Ignition Facility. A scaling estimate for the radiation temperature versus pulse duration for different size NIF hohlraums is shown in Figure 1. Note that a radiation temperature of about 650 ev is projected for a so-called scale 1 hohlraum (length 2.6mm, diameter 1.6mm). With such high temperature hohlraums, for example, opacity experiments could be carried out using more relevant high Z materials rather than low Z surrogates. These projections of high temperature hohlraums are uncertain, since the scaling model does not allow for the very strongly-driven laser plasma coupling physics. Lasnex calculations have been carried out to estimate the plasma and irradiation conditions in a scale 1 hohlraum driven by NIF. Linear instability gains as high as exp(100) have been found for stimulated Brillouin scattering, and other laser-driven instabilities are also far above their thresholds. More understanding of the very strongly-driven coupling physics is clearly needed in order to more realistically assess and improve the prospects for high temperature hohlraums. Not surprisingly, this regime has been avoided for inertial fusion applications and so is relatively unexplored.

  5. Electron Attachment to POCl3: Measurement and Theoretical Analysis of Rate Constants and Branching Ratios as a Function of Gas Pressure and Temperature, Electron Temperature, and Electron Energy

    DTIC Science & Technology

    2006-03-31

    the pulse along the flow tube axis variation in the total rate constant with temperature.2 In con- with the Langmuir probe . In the electron-He+-Ar...calculations 5 reported in Ref. 4 and should cylindrical Langmuir probe . The plasma velocity is measured be reliable within ±0.1 eV. Electron attachment...increasing temperature decreased diffusion. the amount of parent ion substantially in flowing - afterglow In the present work, POCI3 gas was added

  6. The Ionization Equilibrium of Optically Thick Argon Z-Pinch Plasmas for Electron Temperatures between 25 and 65 eV.

    DTIC Science & Technology

    2014-09-26

    reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP " Ioni;ation equilibrium Argon plasma Gamble -Il generator Collisional pumping...highly attractive due to the large gain lengths (up to 4 cm) and immense energies (-1 MJ) available to couple to the plasma. The Gamble -II device at...previously observed1 5. These results suggest that Gamble -II would be an excellent device to test lasing concepts on a Z-pinch. Argon, stripped to the neon

  7. Electron evaporation from an ultracold plasma in a uniform electric field

    NASA Astrophysics Data System (ADS)

    Twedt, K. A.; Rolston, S. L.

    2010-08-01

    Electrons in an expanding ultracold plasma are expected to be in quasiequilibrium since the collision times are short compared to the plasma lifetime, yet electron evaporation is observed as the ion density decreases during expansion. A small electric field that shifts the electron cloud with respect to the ions increases the evaporation rate. Treating the electrons as a zero-temperature fluid, their spatial distribution is calculated as a function of the applied field strength and the ion density. The zero-temperature approximation gives the maximum number of electrons the plasma can hold in the absence of evaporation. By applying this calculation at all times during expansion, the flux of cold electrons from the plasma is predicted and found to be in good agreement with the observed electron signal.

  8. Observations of ionospheric electron beams in the plasma sheet.

    PubMed

    Zheng, H; Fu, S Y; Zong, Q G; Pu, Z Y; Wang, Y F; Parks, G K

    2012-11-16

    Electrons streaming along the magnetic field direction are frequently observed in the plasma sheet of Earth's geomagnetic tail. The impact of these field-aligned electrons on the dynamics of the geomagnetic tail is however not well understood. Here we report the first detection of field-aligned electrons with fluxes increasing at ~1 keV forming a "cool" beam just prior to the dissipation of energy in the current sheet. These field-aligned beams at ~15 R(E) in the plasma sheet are nearly identical to those commonly observed at auroral altitudes, suggesting the beams are auroral electrons accelerated upward by electric fields parallel (E([parallel])) to the geomagnetic field. The density of the beams relative to the ambient electron density is δn(b)/n(e)~5-13% and the current carried by the beams is ~10(-8)-10(-7) A m(-2). These beams in high β plasmas with large density and temperature gradients appear to satisfy the Bohm criteria to initiate current driven instabilities.

  9. Estimation of excitation temperature by duty ratio of observed period in non-equilibrium plasma

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Muraoka, Sumihiro; Nihei, Takashi; Abe, Seiya

    2017-06-01

    We investigated the excitation temperature of atmospheric-pressure non-equilibrium (cold) plasma using a line-pair method. An atmospheric cold plasma was intermittently generated using a quartz tube, a rare gas, and a foil electrode by applying high-voltage alternating current. Because the plasma occurred intermittently, an interval appeared between each generated plasma bullet. We assessed the time-averaged effective intensity from the observed intensity at each wavelength measured using a spectrometer. When the exposure time of the spectrometer is longer than the observed period of the plasma emission light, the time-averaged effective intensity at each wavelength decreases because it includes the interval with no plasma emission light. The difference in intensity between wavelengths changes with frequency, because changing the frequency changes the interval between plasma bullets. Consequently, even if the plasma electron temperature does not depend on the frequency of the applied voltage, the excitation temperature estimated from the difference in intensity changes with the frequency. The plasma electron temperature can be estimated from the duty ratio of the observed period of plasma emission light, and we estimated the electron temperature in the helium and argon cold plasmas to be 1.0 eV.

  10. Observation of high temperature plasma in nickel wire array implosions

    NASA Astrophysics Data System (ADS)

    Deeney, C.; Nash, T.; LePell, P. D.; Childers, K.; Krishnan, M.

    1989-12-01

    Time- and space-resolved filtered pinhole photography and crystal X-ray spectroscopy have been used to diagnose K-shell emission from nickel wire array implosions on the DNA/Double-EAGLE 6TW generator. In this paper, results are presented which show electron beam induced Ni Kα emission prior to and during a rapid localized heating of the plasma and the formation of intense hot spots. The observation of hydrogen-like nickel lines from the hot spots is indicative of multi-keV electron temperatures.

  11. Electron Acoustic Waves in Pure Ion Plasmas

    NASA Astrophysics Data System (ADS)

    Anderegg, Francois

    2008-11-01

    Electron Acoustic Waves (EAWs) are the low frequency branch of electrostatic plasma waves; these waves exist in neutralized plasmas, pure electrons, and pure ion plasmas. The EAWs typically have a phase velocity Vphase / Vth ˜1.4, quite low compared to typical plasma waves. Linear Landau damping would suggest that such slow phase velocity waves are strongly damped; but at finite wave amplitudes, trapping of particles at the phase velocity effectively flattens the distribution function, resulting in a ``BGK-like'' state with weak damping. Our experiments on standing mz= 1, mθ= 0 waves show that the small-amplitude dispersion relation for both fast Trivelpiece-Gould (TG) and slow (EAW) plasma modes is in close agreement with the ``thumb-shaped'' dispersion relation predicted by kinetic theory neglecting damping. However, the surprise here is that a moderate amplitude ``off-resonant'' drive readily modifies the velocity distribution so as to make the plasma mode resonant with the drive frequency. We have observed the plasma adjusting its velocity distribution so as to become resonant with a 100 cycle drive ranging from 10 kHz to 30 kHz. With a chirped frequency drive, the particle velocity distribution suffers extreme distortion, and the resulting plasma wave is almost undamped with γ/ φ˜10-5. Laser-Induced-Fluorescence measurements of the wave-coherent particle distribution f (vz, t), clearly show particle trapping in the EAW, with trapping widths as expected from theory considering two non-interacting traveling waves forming the standing wave. The coherent f (vz, t ) measurement also shows that particles slower than the wave phase velocity vph oscillate in phase with the wave, contrasting with the 180^o out-of-phase response of the particles moving faster than vph. The differing response of the fast and slow particles results in a small net fluid velocity, because the electrostatic restoring force is almost totally balanced by the kinetic pressure, consistent

  12. Energetic electron spectra in Saturn's plasma sheet

    NASA Astrophysics Data System (ADS)

    Carbary, J. F.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Krupp, N.

    2011-07-01

    The differential spectra of energetic electrons (27-400 keV) in Saturn's plasma sheet can be characterized by power law or kappa distributions. Using all available fluxes from 2005 to 2010, fits to these distributions reveal a striking and consistent pattern of radial dependence in Saturn's plasma sheet (∣z∣ < 1 RS = 60,268 km). The electron spectral indices show harder spectra at large radial distances (20-30 RS), softer spectra at middle radial distances (10-20 RS), and very steep spectra inside the orbit of Rhea (˜8.5 RS). The dayside spectra are somewhat harder than the nightside spectra outside the orbit of Titan (˜20 RS), although there is no local time dependence inside ˜10 RS. This spectral behavior exhibited essentially no dependence on pitch angle and remained remarkably constant throughout the Cassini mission. Inward of about 10 RS, the presence of the electron radiation belts and losses of lower-energy electrons to the gas and grain environment give rise to the very hard spectra in the inner magnetosphere, while the hard spectra in the outer magnetosphere may derive from auroral acceleration at high latitudes. The gradual softening of the spectra from 20 to 10 RS is explained by inward radial diffusion.

  13. The downshift of electron plasma oscillations in the electron foreshock region

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Gurnett, D. A.; Fitzenreiter, R. J.

    1985-01-01

    Electron plasma oscillations in the earth's electron foreshock region are observed to shift above and below the local electron plasma frequency. As plasma oscillations shift downward from the plasma frequency, their bandwidth increases and their wavelength decreases. Observations of plasma oscillations well below the plasma frequency are correlated with times when ISEE 1 is far downstream of the electron foreshock boundary. Although wavelengths of plasma oscillations below the plasma frequency satisfy k x lambda-De approximately 1 the Doppler shift due to the motion of the solar wind is not sufficient to produce the observed frequency shifts. A beam-plasma interaction with beam velocities on the order of the electron thermal velocity is suggested as an explanation for plasma oscillations above and below the plasma frequency. Frequency, bandwidth, and wavelength changes predicted from the beam-plasma interaction are in good agreement with the observed characteristics of plasma oscillations in the foreshock region.

  14. High-temperature plasmas in clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Itoh, Naoki; Kohyama, Yasuharu; Nozawa, Satoshi

    1998-12-01

    Recent developments in the study of high-temperature plasmas in clusters of galaxies are reviewed. The Compton scattering of the permeating 2.7 K cosmic microwave background photons by high-temperature electrons of energy 0953-8984/10/49/016/img5 produces a distortion in the Planck distribution of the 2.7 K cosmic microwave background photons. This effect, which has been termed the Sunyaev-Zel'dovich effect, has been studied extensively in recent years both theoretically and observationally. We will give a review of the study on this subject.

  15. Atomic processes modeling of X-ray free electron laser produced plasmas using SCFLY code

    NASA Astrophysics Data System (ADS)

    Chung, H.-K.; Cho, B. I.; Ciricosta, O.; Vinko, S. M.; Wark, J. S.; Lee, R. W.

    2017-03-01

    With the development of X-ray free electron lasers (XFEL), a novel state of matter of highly transient and non-equilibrium plasma has been created in laboratories. As high intensity X-ray laser beams interact with a solid density target, electrons are ionized from inner-shell orbitals and these electrons and XFEL photons create dense and finite temperature plasmas. In order to study atomic processes in XFEL driven plasmas, the atomic kinetics model SCFLY containing an extensive set of configurations needed for solid density plasmas was applied to study atomic processes of XFEL driven systems. The code accepts the time-dependent conditions of the XFEL as input parameters, and computes time-dependent population distributions and ionization distributions self-consistently with electron temperatures and densities assuming an instantaneous equilibration of electron energies. The methods and assumptions in the atomic kinetics model and unique aspects of atomic processes in XFEL driven plasmas are described.

  16. Radial Profiles of the Plasma Electron Characteristics in a 30 kW Arc Jet

    NASA Technical Reports Server (NTRS)

    Codron, Douglas A.; Nawaz, Anuscheh

    2013-01-01

    The present effort aims to strengthen modeling work conducted at the NASA Ames Research Center by measuring the critical plasma electron characteristics within and slightly outside of an arc jet plasma column. These characteristics are intended to give physical insights while assisting in the formulation of boundary conditions to validate full scale simulations. Single and triple Langmuir probes have been used to achieve estimates of the electron temperature (T(sub e)), electron number density (n(sub e)) and plasma potential (outside of the plasma column) as probing location is varied radially from the flow centerline. Both the electron temperature and electron number density measurements show a large dependence on radial distance from the plasma column centerline with T(sub e) approx. = (3 - 12 eV and n(sub e) approx. = 10(exp 12) - 10(exp 14)/cu cm.

  17. Modeling of free electronic state density in hydrogenic plasmas based on nearest neighbor approximation

    SciTech Connect

    Nishikawa, Takeshi

    2014-07-15

    Most conventional atomic models in a plasma do not treat the effect of the plasma on the free-electron state density. Using a nearest neighbor approximation, the state densities in hydrogenic plasmas for both bound and free electrons were evaluated and the effect of the plasma on the atomic model (especially for the state density of the free electron) was studied. The model evaluates the electron-state densities using the potential distribution formed by the superposition of the Coulomb potentials of two ions. The potential from one ion perturbs the electronic state density on the other. Using this new model, one can evaluate the free-state density without making any ad-hoc assumptions. The resulting contours of the average ionization degree, given as a function of the plasma temperature and density, are shifted slightly to lower temperatures because of the effect of the increasing free-state density.

  18. Kinetic modelling of runaway electron avalanches in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Nilsson, E.; Decker, J.; Peysson, Y.; Granetz, R. S.; Saint-Laurent, F.; Vlainic, M.

    2015-09-01

    relative importance of the avalanche mechanism is investigated as a function of the key parameters for runaway electron formation, namely the plasma temperature and the electric field strength. In agreement with theoretical predictions, the LUKE simulations show that in low temperature and electric field the knock-on collisions becomes the dominant source of runaway electrons and can play a significant role for runaway electron generation, including in non-disruptive tokamak scenarios.

  19. Plasma synthesis of high temperature ceramic films

    SciTech Connect

    Brown, I.G.; Monteiro, O.R.

    1998-11-01

    Thin films of alumina, chromia, mullite, yttria and zirconia have been synthesized using a plasma-based method called metal plasma immersion ion implantation and deposition (Mepiiid)--a highly versatile plasma deposition technique with ion energy control. Monolithic films (a single ceramic component) and multilayer films (individual layers of different ceramic materials) were formed. The films were characterized for their composition and structure in a number of different ways, and the high temperature performance of the films was explored, particularly for their ability to maintain their integrity and adhesion when subjected to repetitive high temperature thermal cycling up 1100 C. We found that the films retain their adhesion and quality without any apparent degradation with time, even after a large number of cycles; (the tests were extended out to a total of 40 cycles each of 24 hours duration). After repetitive high temperature thermal cycling, the film-substrate adhesion was greater than {approx}70 Mpa, the instrumental limit of measurement, and the interface toughness was approximately 0.8 MPa m{sup 1/2}.

  20. Magnetosonic wave in pair-ion electron collisional plasmas

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Hasnain, H.

    2017-03-01

    Low frequency magnetosonic waves in positive and negative ions of equal mass and opposite charges in the presence of electrons in collisional plasmas are studied. The collisions of ions and electrons with neutrals are taken into account. The nonlinearities in the plasma system arise due to ion and electrons flux, Lorentz forces, and plasma current densities. The reductive perturbation method is applied to derive the Damped Korteweg de Vries (DKdV) equation. The time dependent solution of DKdV is presented. The effects of variations of different plasma parameters on propagation characteristics of magnetosonic waves in pair-ion electron plasma in the context of laboratory plasmas are discussed.

  1. Physical properties of dense, low-temperature plasmas

    NASA Astrophysics Data System (ADS)

    Redmer, Ronald

    1997-04-01

    Plasmas occur in a wide range of the density-temperature plane. The physical quantities can be expressed by Green's functions which are evaluated by means of standard quantum statistical methods. The influences of many-particle effects such as dynamic screening and self-energy, structure factor and local-field corrections, formation and decay of bound states, degeneracy and Pauli exclusion principle are studied. As a basic concept for partially ionized plasmas, a cluster decomposition is performed for the self-energy as well as for the polarization function. The general model of a partially ionized plasma interpolates between low-density, nonmetallic systems such as atomic vapors and high-density, conducting systems such as metals or fully ionized plasmas. The equations of state, including the location of the critical point and the shape of the coexistence curve, are determined for expanded alkali-atom and mercury fluids. The occurrence of a metal-nonmetal transition near the critical point of the liquid-vapor phase transition leads in these materials to characteristic deviations from the behavior of nonconducting fluids such as the inert gases. Therefore, a unified approach is needed to describe the drastic changes of the electronic properties as well as the variation of the physical properties with the density. Similar results are obtained for the hypothetical plasma phase transition in hydrogen plasma. The transport coefficients (electrical and thermal conductivity, thermopower) are studied within linear response theory given here in the formulation of Zubarev which is valid for arbitrary degeneracy and yields the transport coefficients for the limiting cases of nondegenerate, weakly coupled plasmas (Spitzer theory) as well as degenerate, strongly coupled plasmas (Ziman theory). This linear response method is applied to partially ionized systems such as dense, low-temperature plasmas. Here, the conductivity changes from nonmetallic values up to those typical for

  2. Thermal equilibrium of a cryogenic magnetized pure electron plasma

    NASA Technical Reports Server (NTRS)

    Dubin, D. H. E.; Oneil, T. M.

    1986-01-01

    The thermal equilibrium correlation properties of a magnetically confined pure electron plasma (McPEP) are related to those of a one-component plasma (OCP). The N-particle spatial distribution rho sub s and the Helmholtz free energy F are evaluated for the McPEP to O(lambda sub d-squared/a-squared), where lambda sub d is the thermal de Broglie wavelength and is an interparticle spacing. The electron gyromotion is allowed to be fully quantized while the guiding center motion is quasi-classical. The distribution rho sub s is shown to be identical to that of a classical OCP with a slightly modified potential. To O(lambda sub d-squared/a-squared) this modification does not affect that part of F that is caused by correlations, as long as certain requirements concerning the size of the plasma are met. This theory is motivated by a current series of experiments that involve the cooling of a magnetically confined pure electron plasma to the cryogenic temperature range.

  3. Thermal equilibrium of a cryogenic magnetized pure electron plasma

    NASA Technical Reports Server (NTRS)

    Dubin, D. H. E.; Oneil, T. M.

    1986-01-01

    The thermal equilibrium correlation properties of a magnetically confined pure electron plasma (McPEP) are related to those of a one-component plasma (OCP). The N-particle spatial distribution rho sub s and the Helmholtz free energy F are evaluated for the McPEP to O(lambda sub d-squared/a-squared), where lambda sub d is the thermal de Broglie wavelength and is an interparticle spacing. The electron gyromotion is allowed to be fully quantized while the guiding center motion is quasi-classical. The distribution rho sub s is shown to be identical to that of a classical OCP with a slightly modified potential. To O(lambda sub d-squared/a-squared) this modification does not affect that part of F that is caused by correlations, as long as certain requirements concerning the size of the plasma are met. This theory is motivated by a current series of experiments that involve the cooling of a magnetically confined pure electron plasma to the cryogenic temperature range.

  4. Thomson scattering from near-solid density plasmas using soft x-ray free electron lasers

    SciTech Connect

    Holl, A; Bornath, T; Cao, L; Doppner, T; Dusterer, S; Forster, E; Fortmann, C; Glenzer, S H; Gregori, G; Laarmann, T; Meiwes-Broer, K H; Przystawik, A; Radcliffe, P; Redmer, R; Reinholz, H; Ropke, G; Thiele, R; Tiggesbaumker, J; Toleikis, S; Truong, N X; Tschentscher, T; Uschmann, I; Zastrau, U

    2006-11-21

    We propose a collective Thomson scattering experiment at the VUV free electron laser facility at DESY (FLASH) which aims to diagnose warm dense matter at near-solid density. The plasma region of interest marks the transition from an ideal plasma to a correlated and degenerate many-particle system and is of current interest, e.g. in ICF experiments or laboratory astrophysics. Plasma diagnostic of such plasmas is a longstanding issue. The collective electron plasma mode (plasmon) is revealed in a pump-probe scattering experiment using the high-brilliant radiation to probe the plasma. The distinctive scattering features allow to infer basic plasma properties. For plasmas in thermal equilibrium the electron density and temperature is determined from scattering off the plasmon mode.

  5. Material for electrodes of low temperature plasma generators

    DOEpatents

    Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich

    2008-12-09

    Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron: 3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, and municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

  6. Material for electrodes of low temperature plasma generators

    DOEpatents

    Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich; Shiryaev, Vasili Nikolaevich

    2010-03-02

    Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron:3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

  7. Probing Runaway Electrons with Nanoparticle Plasma Jet

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.

    2014-10-01

    The injection of C60/C nanoparticle plasma jet (NPPJ) into tokamak plasma during a major disruption has the potential to probe the runaway electrons (REs) during different phases of their dynamics and diagnose them through spectroscopy of C ions visible/UV lines. A C60/C NPPJ of ~75 mg, high-density (>1023 m-3), hyper-velocity (>4 km/s), and uniquely fast response-to-delivery time (~1 ms) has been demonstrated on a test bed. It can rapidly and deeply deliver enough mass to increase electron density to ~2.4 × 1021 m-3, ~60 times larger than typical DIII-D pre-disruption value. We will present the results of our investigations on: 1) C60 fragmentation and gradual release of C atoms along C60 NPPJ penetration path through the RE carrying residual cold plasma, 2) estimation of photon emissivity coefficient for the lines of the C ions, and 3) simulation of C60/C PJ penetration to the RE beam location in equivalent conditions to the characteristic ~1 T B-field of DIII-D. The capabilities of this injection technique provide a unique possibility in understanding and controlling the RE beam, which is a critical problem for ITER. Work supported by US DOE DE-SC0011864 Grant.

  8. Simulations of Temperatures in Burning Tokamak Plasmas using the GLF23 Model in the TRANSP Code

    SciTech Connect

    R.V. Budny

    2002-08-13

    The GLF23 prediction model, incorporated in the TRANSP plasma analysis code, is used to predict temperatures for burning plasmas in the proposed FIRE and ITER-FEAT tokamaks. Flat electron density profiles with various central values are assumed. Scaling of the fusion power P(subscript)dt and gain Q(subscript)dt with density (subscript)and pedestal temperature are given. Helium ash transport and sawtooth effect Pdt in long duration ITER-FEAT plasmas.

  9. Soliton formation in ion temperature gradient driven magneto-plasma

    NASA Astrophysics Data System (ADS)

    Iqbal, Javed; Khan, M. Yaqub

    2017-04-01

    Ion-temperature-gradient (ITG) driven solitons are studied in a plasma having gradients. We drive an admitted solitary wave solution Korteweg-de Vries-type equation for the ITG mode in the non-linear regime by using Braginskii model and a transformation. It was observed that the soliton amplitude and width are sensitive to the parameter η i = L n / L T , the ratio of electron temperature gradient, and the gradient scale length. It is also observed that increasing the ion temperature and increasing the magnetic field affect the shape of the soliton. We apply homotopy perturbation method (HPM) technique on the derived KdV equation. It was found that this method is computationally attractive and that the results of this method are in agreement with the exact solution. This work may be useful to study the low electrostatic modes in in-homogeneous electron-ion plasma having density and ITG gradients. For illustration, the model has been applied to tokamak plasma.

  10. Plasma parameters controlled by remote electron shower in a double plasma device

    NASA Astrophysics Data System (ADS)

    Mishra, M. K.; Phukan, A.

    2012-07-01

    The principal feature of this experiment is the electron showers consisting of three tungsten wires embedded by the plasma, which are heated up consequently emitting electrons inside the diffused plasma to control the plasma parameters in the discharge section of a double plasma device. These cold electrons emitted by the heated filament are free from maintenance of discharge which is sustained in the source section. The target plasma, where electrons are injected is produced as a result of diffusion from the source section. It is found that, plasma density and plasma potential can be effectively controlled in this way.

  11. Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons

    SciTech Connect

    Khotyaintsev, Yu. V.; Cully, C. M.; Vaivads, A.; Andre, M.; Owen, C. J.

    2011-04-22

    We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth's magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.

  12. Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons

    NASA Astrophysics Data System (ADS)

    Khotyaintsev, Yu. V.; Cully, C. M.; Vaivads, A.; André, M.; Owen, C. J.

    2011-04-01

    We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth’s magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.

  13. Plasma jet braking: energy dissipation and nonadiabatic electrons.

    PubMed

    Khotyaintsev, Yu V; Cully, C M; Vaivads, A; André, M; Owen, C J

    2011-04-22

    We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth's magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.

  14. Simulating strongly coupled plasmas at low temperatures

    NASA Astrophysics Data System (ADS)

    Bussmann, M.; Schramm, U.; Habs, D.

    2006-10-01

    Realistic molecular dynamics (MD) simulations of the particle dynamics in strongly coupled plasmas require the computation of the mutual Coulomb-force for each pair of charged particles if a correct treatment of long range correlations is required. For plasmas with N > 104 particles this requires a tremendous number of computational steps which can only be addressed using efficient parallel algorithms adopted to modern super-computers. We present a new versatile MD simulation code which can simulate the non-relativistic mutual Coulomb-interaction of a large number of charged particles in arbitrary external field configurations. A demanding application is the simulation of the complete dynamics of in-trap stopping of highly charged ions in a laser cooled plasma of N = 105 24Mg+ ions. We demonstrate that the simulation is capable of delivering results on stopping times and plasma dynamics under realistic conditions. The results suggest that this stopping scheme can compete with in-trap electron cooling and might be an alternative approach for delivering ultra cold highly charged ions for future trap-based experiments aiming for precision mass measurements of stable and radioactive nuclei.

  15. Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves.

    PubMed

    Schroeder, C B; Esarey, E

    2010-05-01

    A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a nonrelativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for Langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three-velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for nonrelativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.

  16. Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves

    SciTech Connect

    Schroeder, Carl B.; Esarey, Eric

    2010-06-30

    A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically-intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a non-relativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined, and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for non-relativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.

  17. Implicit two-fluid simulation of electron transport in a plasma erosion opening switch

    SciTech Connect

    Mason, R.J.; Wallace, J.M.; Lee, K.

    1986-01-01

    The two-dimensional implicit code ANTHEM is used to model electron transport in Plasma Opening Switches. We look at low density (approx.4 x 10/sup 12/cm/sup -3/) switches at initial plasma temperatures as low as 5 eV. Two-fluid modeling (ions and electrons with inertia) and implicit determination of the fields is employed to allow time steps well in excess of the inverse plasma period, and cell sizes much larger than a Debye length - with the avoidance of the finite grid anomalous plasma heating characteristic of particle codes. Features indicative of both erosion and E > B plasma drift are manifest in the simulations.

  18. Enhanced Plasma Lifetime of Air Plasmas Generated by Electron Beam Excitation

    NASA Astrophysics Data System (ADS)

    Vidmar, Robert; Stalder, Kenneth

    2002-10-01

    A kinetic model with an improved set of reaction rate coefficients for air constituents will be discussed. The model includes rates that vary with E/N for electron temperature, momentum transfer, three body attachment, singlet-delta formation, electron detachment from O2-, and ionization of O2. The electric field is assumed uniform and sustained either by external electrodes or return currents generated in an electron beam. Calculations show the plasma lifetime increases as E/N increases by reducing attachment, increasing detachment, and increasing ionization. Electric-field-free plasma lifetimes of 10-20 ns for air at sea level (depending on initial electron density) can be increased by a factor of almost 5 with an E/N of about 2 x 10-16 volt cm^2. The plasma lifetime at altitudes of 30,000 feet corresponds to 60-100 ns without electric field and increases by a factor of 5-20 with an E/N of 5 x 10-17 volt cm^2. The power to maintain these E/N values and to sustain a given level of plasma density will be discussed. This research is sponsored by the Air Force Research Laboratory, under agreement number F49620-01-1-0414.

  19. Pair correlation functions of strongly coupled two-temperature plasma

    NASA Astrophysics Data System (ADS)

    Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.

    2017-09-01

    Using molecular dynamics simulations, we perform the first direct tests of three proposed models for the pair correlation functions of strongly coupled plasmas with species of unequal temperature. The models are all extensions of the Ornstein-Zernike/hypernetted-chain theory used to good success for equilibrium plasmas. Each theory is evaluated at several coupling strengths, temperature ratios, and mass ratios for a model plasma in which the electrons are positively charged. We show that the model proposed by Seuferling et al. [Phys. Rev. A 40, 323 (1989)] agrees well with molecular dynamics over a wide range of mass and temperature ratios, as well as over a range of coupling strength similar to that of the equilibrium hypernetted-chain (HNC) theory. The SVT model also correctly predicts the strength of interspecies correlations and exhibits physically reasonable long-wavelength limits of the static structure factors. Comparisons of the SVT model with the Yukawa one-component plasma (YOCP) model are used to show that ion-ion pair correlations are well described by the YOCP model up to Γe≈1 , beyond which it rapidly breaks down.

  20. Excitation of Plasma Waves in Aurora by Electron Beams

    NASA Technical Reports Server (NTRS)

    daSilva, C. E.; Vinas, A. F.; deAssis, A. S.; deAzevedo, C. A.

    1996-01-01

    In this paper, we study numerically the excitation of plasma waves by electron beams, in the auroral region above 2000 km of altitude. We have solved the fully kinetic dispersion relation, using numerical method and found the real frequency and the growth rate of the plasma wave modes. We have examined the instability properties of low-frequency waves such as the Electromagnetic Ion Cyclotron (EMIC) wave as well as Lower-Hybrid (LH) wave in the range of high-frequency. In all cases, the source of free energy are electron beams propagating parallel to the geomagnetic field. We present some features of the growth rate modes, when the cold plasma parameters are changed, such as background electrons and ions species (H(+) and O(+)) temperature, density or the electron beam density and/or drift velocity. These results can be used in a test-particle simulation code, to investigate the ion acceleration and their implication in the auroral acceleration processes, by wave-particle interaction.

  1. Excitation of Plasma Waves in Aurora by Electron Beams

    NASA Technical Reports Server (NTRS)

    daSilva, C. E.; Vinas, A. F.; deAssis, A. S.; deAzevedo, C. A.

    1996-01-01

    In this paper, we study numerically the excitation of plasma waves by electron beams, in the auroral region above 2000 km of altitude. We have solved the fully kinetic dispersion relation, using numerical method and found the real frequency and the growth rate of the plasma wave modes. We have examined the instability properties of low-frequency waves such as the Electromagnetic Ion Cyclotron (EMIC) wave as well as Lower-Hybrid (LH) wave in the range of high-frequency. In all cases, the source of free energy are electron beams propagating parallel to the geomagnetic field. We present some features of the growth rate modes, when the cold plasma parameters are changed, such as background electrons and ions species (H(+) and O(+)) temperature, density or the electron beam density and/or drift velocity. These results can be used in a test-particle simulation code, to investigate the ion acceleration and their implication in the auroral acceleration processes, by wave-particle interaction.

  2. Electron plasma wave filamentation in the kinetic regime

    NASA Astrophysics Data System (ADS)

    Lushnikov, Pavel; Rose, Harvey; Silantyev, Denis

    2016-10-01

    We consider nonlinear electron plasma wave (EPW) dynamics in the kinetic wavenumber regime, 0.25 < kλD < 0.45 , which is typical for current high temperature laser-plasma interaction experiments, where k is the EPW wavenumber and λD is the electron Debye length. In this kinetic regime, EPW frequency reduction due to electron trapping may dominate the ponderomotive frequency shift. Previous 3D PIC simulations showed that the trapped electron EPW filamentation instability can saturate stimulated Raman backscatter by reducing the EPWs coherence but multidimensional Vlasov simulations [1] are needed to address that saturation in details. We performed nonlinear, non-equilibrium 2D Vlasov simulations to study the EPW filamentation. The initial conditions are created either by external forcing or by constructing the appropriate 1D travelling Bernstein-Greene-Kruskal (BGK) mode. Transverse perturbations of any of these initial conditions grow with time eventually producing strongly nonlinear filamentation followed by plasma turbulence. We compared these simulations with the theoretical results on growth rates of the transverse instability BGK mode showing the satisfactory agreement. Supported by the New Mexico Consortium and NSF DMS-1412140.

  3. Plasma treatment for producing electron emitters

    DOEpatents

    Coates, Don Mayo; Walter, Kevin Carl

    2001-01-01

    Plasma treatment for producing carbonaceous field emission electron emitters is disclosed. A plasma of ions is generated in a closed chamber and used to surround the exposed surface of a carbonaceous material. A voltage is applied to an electrode that is in contact with the carbonaceous material. This voltage has a negative potential relative to a second electrode in the chamber and serves to accelerate the ions toward the carbonaceous material and provide an ion energy sufficient to etch the exposed surface of the carbonaceous material but not sufficient to result in the implantation of the ions within the carbonaceous material. Preferably, the ions used are those of an inert gas or an inert gas with a small amount of added nitrogen.

  4. Electron-helium scattering in Debye plasmas

    SciTech Connect

    Zammit, Mark C.; Fursa, Dmitry V.; Bray, Igor; Janev, R. K.

    2011-11-15

    Electron-helium scattering in weakly coupled hot-dense (Debye) plasma has been investigated using the convergent close-coupling method. The Yukawa-type Debye-Hueckel potential has been used to describe plasma Coulomb screening effects. Benchmark results are presented for momentum transfer cross sections, excitation, ionization, and total cross sections for scattering from the ground and metastable states of helium. Calculations cover the entire energy range up to 1000 eV for the no screening case and various Debye lengths (5-100 a{sub 0}). We find that as the screening interaction increases, the excitation and total cross sections decrease, while the total ionization cross sections increase.

  5. Dynamics of runaway electrons in magnetized plasmas

    SciTech Connect

    Moghaddam-Taaheri, E.

    1986-01-01

    The evolution of a runaway electron tail driven by a subcritical dc electric field in a magnetized plasma is studied numerically using a quasi-linear numerical code (2-D in v- and k-space) based on the Ritz-Galerkin method and finite elements. Three different regimes in the evolution of the runaway tail depending on the strength of the dc electric field and the ratio of plasma to gyrofrequency, were found. The tail can be (a) stable and the electrons are accelerated to large parallel velocities, (b) unstable to the Cerenkov resonance due to the formation of a positive slope on the runaway tail, (c) unstable to the anomalous Doppler resonance instability driven by the large velocity anisotropy in the tail. Once an instability is triggered (Cerenkov or anomalous Doppler resonance) the tail relaxes into an isotropic distribution resulting in less acceleration. The synchrotron emission of the runaway electrons shows large enhancement in the radiation level at the high-frequency end of the spectrum during the pitch-angle scattering of the fast particles. The results are relevant to recent experimental data from the Princeton Large Torus (PLT) during current-drive experiments and to the microwave bursts observed during solar flares.

  6. Low temperature plasma biomedicine: A tutorial review

    SciTech Connect

    Graves, David B.

    2014-08-15

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown to be potentially useful for surface and wound sterilization, antisepsis, bleeding cessation, wound healing, and cancer treatment, among other biomedical applications. This tutorial review summarizes the field, stressing the likely role of reactive oxygen and nitrogen species created in these plasmas as the biologically and therapeutically active agents. Reactive species, including radicals and non-radical compounds, are generated naturally within the body and are now understood to be essential for normal biological functions. These species are known to be active agents in existing therapies for wound healing, infection control, and cancer treatment. But they are also observed at elevated levels in persons with many diseases and are associated with aging. The physical and chemical complexity of plasma medical devices and their associated biochemical effects makes the development of safe, effective plasma medical devices and procedures a challenge, but encouragingly rapid progress has been reported around the world in the last several years.

  7. Low temperature plasma biomedicine: A tutorial reviewa)

    NASA Astrophysics Data System (ADS)

    Graves, David B.

    2014-08-01

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown to be potentially useful for surface and wound sterilization, antisepsis, bleeding cessation, wound healing, and cancer treatment, among other biomedical applications. This tutorial review summarizes the field, stressing the likely role of reactive oxygen and nitrogen species created in these plasmas as the biologically and therapeutically active agents. Reactive species, including radicals and non-radical compounds, are generated naturally within the body and are now understood to be essential for normal biological functions. These species are known to be active agents in existing therapies for wound healing, infection control, and cancer treatment. But they are also observed at elevated levels in persons with many diseases and are associated with aging. The physical and chemical complexity of plasma medical devices and their associated biochemical effects makes the development of safe, effective plasma medical devices and procedures a challenge, but encouragingly rapid progress has been reported around the world in the last several years.

  8. Measurements of low-energy electron reflection at a plasma boundary

    SciTech Connect

    Demidov, V. I.; Adams, S. F.; Kaganovich, I. D.; Koepke, M. E.; Kurlyandskaya, I. P.

    2015-10-15

    It is demonstrated that low-energy (<3 eV) electron reflection from a solid surface in contact with a low-temperature plasma can have significant variation with time. An uncontaminated, i.e., “clean,” metallic surface (just after heating up to glow) in a plasma environment may have practically no reflection of low-energy incident electrons. However, a contaminated, i.e., “dirty,” surface (in some time after cleaning by heating) that has a few monolayers of absorbent can reflect low-energy incident electrons and therefore significantly affect the net electron current collected by the surface. This effect may significantly change plasma properties and should be taken into account in plasma experiments and models. A diagnostic method is demonstrated for measurements of low-energy electron absorption coefficient in plasmas with a mono-energetic electron group.

  9. Electron Recombination in a Dense Hydrogen Plasma

    SciTech Connect

    Jana, M.R.; Johnstone, C.; Kobilarcik, T.; Koizumi, G.M.; Moretti, A.; Popovic, M.; Tollestrup, A.V.; Yonehara, K.; Leonova, M.A.; Schwarz, T.A.; Chung, M.; /Unlisted /IIT, Chicago /Fermilab /MUONS Inc., Batavia /Turin Polytechnic

    2012-05-01

    A high pressure hydrogen gas filled RF cavity was subjected to an intense proton beam to study the evolution of the beam induced plasma inside the cavity. Varying beam intensities, gas pressures and electric fields were tested. Beam induced ionized electrons load the cavity, thereby decreasing the accelerating gradient. The extent and duration of this degradation has been measured. A model of the recombination between ionized electrons and ions is presented, with the intent of producing a baseline for the physics inside such a cavity used in a muon accelerator. Analysis of the data taken during the summer of 2011 shows that self recombination takes place in pure hydrogen gas. The decay of the number of electrons in the cavity once the beam is turned off indicates self recombination rather than attachment to electronegative dopants or impurities. The cross section of electron recombination grows for larger clusters of hydrogen and so at the equilibrium of electron production and recombination in the cavity, processes involving H{sub 5}{sup +} or larger clusters must be taking place. The measured recombination rates during this time match or exceed the analytic predicted values. The accelerating gradient in the cavity recovers fully in time for the next beam pulse of a muon collider. Exactly what the recombination rate is and how much the gradient degrades during the 60 ns muon collider beam pulse will be extrapolated from data taken during the spring of 2012.

  10. Thermalization of electrons in decaying extreme ultraviolet photons induced low pressure argon plasma

    NASA Astrophysics Data System (ADS)

    Beckers, J.; van der Horst, R. M.; Osorio, E. A.; Kroesen, G. M. W.; Banine, V. Y.

    2016-06-01

    We monitored—in the pressure range: 0.5-15 Pa—the electron temperature in decaying plasmas induced in argon gas by pulsed irradiation with extreme ultraviolet (EUV) photons with wavelengths closely around 13.5 nm. For this purpose, temporal measurements of the space-averaged and electric field weighted electron density after pulsed EUV irradiation are combined with an ambipolar diffusion model of the plasma. Results demonstrate that electrons are thermalized to room temperature before the plasma has fully expanded to the chamber walls for pressures of 3 Pa and higher. At pressures below 3 Pa, the electron temperature was found to be up to 0.1 eV above room temperature which is explained by the fact that plasma expansion is too quick for the electrons to fully thermalize. The comparison between plasma expansion duration towards a surface, plasma decay at a surface and time needed for thermalization and cooling of electrons is essential for designers of EUV lithography tools and EUV sources since the temperature of electrons dictates many fundamental physical processes.

  11. [Electron cyclotron resonance (ECR) plasma film deposition

    SciTech Connect

    1999-04-01

    During the third quarter of 1995, an electron cyclotron resonance (ECR) plasma film deposition facility was constructed at the University of New Mexico. This work was conducted in support of the Los Alamos/Tycom CRADA agreement to pursue methods of improving drill bit lifetime. Work in the fourth quarter will center on the coating of drill bits and the treating and testing of various test samples. New material systems as well as treatment techniques will be attempted during this period. The following is a brief description of the various subsystems of the film deposition facility. Particular emphasis is placed on the slotted waveguide system as requested.

  12. In situ electromagnetic field diagnostics with an electron plasma in a Penning-Malmberg trap

    NASA Astrophysics Data System (ADS)

    Amole, C.; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Butler, E.; Capra, A.; Cesar, C. L.; Charlton, M.; Deller, A.; Evetts, N.; Eriksson, S.; Fajans, J.; Friesen, T.; Fujiwara, M. C.; Gill, D. R.; Gutierrez, A.; Hangst, J. S.; Hardy, W. N.; Hayden, M. E.; Isaac, C. A.; Jonsell, S.; Kurchaninov, L.; Little, A.; Madsen, N.; McKenna, J. T. K.; Menary, S.; Napoli, S. C.; Olchanski, K.; Olin, A.; Pusa, P.; Rasmussen, C. Ø.; Robicheaux, F.; Sarid, E.; Silveira, D. M.; So, C.; Stracka, S.; Tharp, T.; Thompson, R. I.; van der Werf, D. P.; Wurtele, J. S.

    2014-01-01

    We demonstrate a novel detection method for the cyclotron resonance frequency of an electron plasma in a Penning-Malmberg trap. With this technique, the electron plasma is used as an in situ diagnostic tool for the measurement of the static magnetic field and the microwave electric field in the trap. The cyclotron motion of the electron plasma is excited by microwave radiation and the temperature change of the plasma is measured non-destructively by monitoring the plasma's quadrupole mode frequency. The spatially resolved microwave electric field strength can be inferred from the plasma temperature change and the magnetic field is found through the cyclotron resonance frequency. These measurements were used extensively in the recently reported demonstration of resonant quantum interactions with antihydrogen.

  13. High sensitivity imaging Thomson scattering for low temperature plasma

    SciTech Connect

    Meiden, H. J. van der; Al, R. S.; Barth, C. J.; Donne, A. J. H.; Goedheer, W. J.; Groot, B. de; Koppers, W. R.; Pol, M. J. van de; Prins, P. R.; Shumack, A. E.; Smeets, P. H. M.; Vijvers, W. A. J.; Westerhout, J.; Wright, G. M.; Rooij, G. J. van; Engeln, R.; Kleyn, A. W.; Lopes Cardozo, N. J.; Schram, D. C.

    2008-01-15

    A highly sensitive imaging Thomson scattering system was developed for low temperature (0.1-10 eV) plasma applications at the Pilot-PSI linear plasma generator. The essential parts of the diagnostic are a neodymium doped yttrium aluminum garnet laser operating at the second harmonic (532 nm), a laser beam line with a unique stray light suppression system and a detection branch consisting of a Littrow spectrometer equipped with an efficient detector based on a ''Generation III'' image intensifier combined with an intensified charged coupled device camera. The system is capable of measuring electron density and temperature profiles of a plasma column of 30 mm in diameter with a spatial resolution of 0.6 mm and an observational error of 3% in the electron density (n{sub e}) and 6% in the electron temperature (T{sub e}) at n{sub e}=4x10{sup 19} m{sup -3}. This is achievable at an accumulated laser input energy of 11 J (from 30 laser pulses at 10 Hz repetition frequency). The stray light contribution is below 9x10{sup 17} m{sup -3} in electron density equivalents by the application of a unique stray light suppression system. The amount of laser energy that is required for a n{sub e} and T{sub e} measurement is 7x10{sup 20}/n{sub e} J, which means that single shot measurements are possible for n{sub e}>2x10{sup 21} m{sup -3}.

  14. Energy Measurements of Trapped Electrons from a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neil; Berry, Melissa; Blumenfeld, Ian; Decker, Franz-Josef; Hogan, Mark J.; Ischebeck, Rasmus; Iverson, Richard; Siemann, Robert H.; Walz, Dieter; Auerbach, David; Clayton, Christopher E.; Huang, Chengkun; Johnson, Devon; Joshi, Chandrashekhar; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Zhou, Miaomiao; Katsouleas, Thomas; Muggli, Patric

    2006-11-27

    Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC indicate trapping of plasma electrons. More charge came out of than went into the plasma. Most of this extra charge had energies at or below the 10 MeV level. In addition, there were trapped electron streaks that extended from a few GeV to tens of GeV, and there were mono-energetic trapped electron bunches with tens of GeV in energy.

  15. Energy Measurements of Trapped Electrons from a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neal; Auerbach, David; Berry, Melissa; Blumenfeld, Ian; Clayton, Christopher E.; Decer, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Johnson, Devon; Joshi, Chadrashekhar; Katsouleas, Thomas; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Muggli, Patric; Oz, Erdem; Siemann, Robert H.; Walz, Dieter; Zhou, Miaomiao; /SLAC /UCLA /Southern California U.

    2007-01-03

    Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC indicate trapping of plasma electrons. More charge came out of than went into the plasma. Most of this extra charge had energies at or below the 10 MeV level. In addition, there were trapped electron streaks that extended from a few GeV to tens of GeV, and there were mono-energetic trapped electron bunches with tens of GeV in energy.

  16. The investigation of electron-ion radiative and dielectronic recombination in high-temperature plasmas. Progress report for 1992--1993

    SciTech Connect

    Jacobs, V.L.

    1993-12-31

    This paper describes progress covered in the following six areas: (1) unified description of radiative and dielectronic recombination; (2) calculations of specific dielectronic satellite transitions; (3) Modeling of K{sub {alpha}} dielectronic satellite spectra; (4) effects of electron collisions and electric fields; (5) density-sensitive dielectronic satellite lines; and (6) polarization of atomic radiative emission in crossed electric and magnetic fields. Also discussed are proposed investigations and coordination with current tokamak observations.

  17. Mitigation of hot electrons from laser-plasma instabilities in high-Z, highly ionized plasmas

    NASA Astrophysics Data System (ADS)

    Fein, J. R.; Holloway, J. P.; Trantham, M. R.; Keiter, P. A.; Edgell, D. H.; Froula, D. H.; Haberberger, D.; Frank, Y.; Fraenkel, M.; Raicher, E.; Shvarts, D.; Drake, R. P.

    2017-03-01

    Hard x-ray measurements are used to infer production of hot electrons in laser-irradiated planar foils of materials ranging from low- to high-Z. The fraction of laser energy converted to hot electrons, fhot , was reduced by a factor of 103 going from low-Z CH to high-Z Au, and hot electron temperatures were reduced from 40 to ˜20 keV. The reduction in fhot correlates with steepening electron density gradient length-scales inferred from plasma refraction measurements. Radiation hydrodynamic simulations predicted electron density profiles in reasonable agreement with those from measurements. Both multi-beam two-plasmon decay (TPD) and multi-beam stimulated Raman scattering (SRS) were predicted to be above threshold with linear threshold parameters that decreased with increasing Z due to steepening length-scales, as well as enhanced laser absorption and increased electron plasma wave collisional and Landau damping. The results add to the evidence that SRS may play a comparable or a greater role relative to TPD in generating hot electrons in multi-beam experiments.

  18. Dynamics of a helium plasma sheet created by a hollow-cathode electron beam

    NASA Astrophysics Data System (ADS)

    Larigaldie, S.; Caillault, L.

    2000-12-01

    A hollow-cathode device has been shown to operate as a plasma reflector for electronic steering of radar beams using helium in the 0.2-0.5 Torr pressure range. Compared to previous experiments, the use of this light gas significantly reduces the spurious sputtering effects on the cathode materials. A semi-quantitative physical model was developed to describe the observed evolution of microwave beam transmissions through the plasma sheet as a function of frequency. This model stresses the importance of electron-ion recombination on the edge of the plasma sheet, due to simultaneous low electron temperatures and high electron densities.

  19. High temperature electronic gain device

    DOEpatents

    McCormick, J. Byron; Depp, Steven W.; Hamilton, Douglas J.; Kerwin, William J.

    1979-01-01

    An integrated thermionic device suitable for use in high temperature, high radiation environments. Cathode and control electrodes are deposited on a first substrate facing an anode on a second substrate. The substrates are sealed to a refractory wall and evacuated to form an integrated triode vacuum tube.

  20. Status of Plasma Electron Hose Instability Studies in FACET

    SciTech Connect

    Adli, Erik; England, Robert Joel; Frederico, Joel; Hogan, Mark; Li, Selina Zhao; Litos, Michael Dennis; Nosochkov, Yuri; An, Weiming; Mori, Warren; /UCLA

    2011-12-13

    In the FACET plasma-wakefield acceleration experiment a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electron hose instability. The FACET plasma-wakefield experiment at SLAC will study beam driven plasma wakefield acceleration. A dense 23 GeV electron beam will interact with lithium or cesium plasma, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons drives the electron hose instability, as first studied by Whittum. While Ref. [2] indicates the possibility of a large instability growth rate for typical beam and plasma parameters, other studies including have shown that several physical effects may mitigate the hosing growth rate substantially. So far there has been no quantitative benchmarking of experimentally observed hosing in previous experiments. At FACET we aim to perform such benchmarking by for example inducing a controlled z-x tilt along the beamentering the plasma, and observing the transverse behavior of the beam in the plasma as function. The long-term objective of these studies is to quantify potential limitations on future plasma wakefield accelerators due to the electron hose instability.

  1. Deriving large electron temperatures and small electron densities with the Cassini Langmuir probe at Saturn

    NASA Astrophysics Data System (ADS)

    Garnier, Philippe; Wahlund, Jan-Erik; Holmberg, Mika; Lewis, Geraint; Schippers, Patricia; Rochel Grimald, Sandrine; Gurnett, Donald; Coates, Andrew; Dandouras, Iannis; Waite, Hunter

    2014-05-01

    The Langmuir Probes (LPs) are commonly used to investigate the cold plasma characteristics in planetary ionospheres/magnetospheres. The LPs performances are limited to low temperatures (i.e. below 5-10 eV at Saturn) and large densities (above several particles/cm3). A strong sensitivity of the Cassini LP measurements to energetic electrons (hundreds eV) may however be observed at Saturn in the L Shell range L=6-10 RS. These electrons impact the surface of the probe and generate a detectable current of secondary electrons. We investigate the influence of such electrons on the current-voltage (I-V) characteristics (for negative potentials), and manage to reproduce the observations with a reasonable precision through empirical and theoretical methods. Conversely, the modelling allows us to derive useful information about the energetic electrons from the LP observations : some information about their pitch angle anisotropy (if combined with the data from a single CAPS ELS anode), as well as an estimate of the electron temperature (in the range 100-300 eV) and of the electron density (above 0.1 particles/cm3). This enlarges the LP measurements capabilities when the influence of the energetic electrons is large (essentially near L=6-10 RS at Saturn). We finally show that a significant influence of the energetic electrons (larger than the contribution of thermal ions) is also expected in various plasma environments of the Solar System, such as at Jupiter (i.e near Ganymede, Europa, Callisto and Io), or even at Earth (in the plasmasheet, the magnetosheath or in plasma cavities). Large electron temperatures and small electron densities could potentially be derived in these environments, which may be of interest for Langmuir Probes in the Earth magnetosphere or onboard the future JUICE mission at Jupiter.

  2. Cathode Plasma Formation in High Intensity Electron Beam Diodes

    NASA Astrophysics Data System (ADS)

    Johnston, Mark; Kiefer, Mark; Oliver, Bryan; Bennett, Nichelle; Droemer, Darryl; Bernshtam, V.; Doron, R.; Maron, Yitzhak

    2013-10-01

    This talk will detail the experimental results and conclusions obtained for cathode plasma formation on the Self-Magnetic Pinch (SMP) diode fielded on the RITS-6 accelerator (4-7.5 MeV) at Sandia National Laboratories. The SMP diode utilizes a hollowed metal cathode to produce high power (TW), focused electron beams (<3 mm diameter) which are used for flash x-ray radiography applications. Optical diagnostics include high speed (<10 ns) framing cameras, optical streak cameras, and spectroscopy. The cathode plasma in this high electric (MV/cm) and magnetic (>10 Tesla) field environment forms well-defined striations. These striations have been examined for a number of different cathode sizes, vacuum gap spacings, and diode voltages. Optical streak images have been taken to determine the time evolution of the plasma, and optical spectroscopy has been employed to determine its constituents as well as their densities and temperatures inferred from detailed time-dependent, collisional-radiative (CR) and radiation transport modelings. Comments will be made as to the overall effect of the cathode plasma in regards to the diode impedance and electron beam focusing. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  3. Multichannel euv spectroscopy of high temperature plasmas

    SciTech Connect

    Fonck, R.J.

    1983-11-01

    Spectroscopy of magnetically confined high temperature plasmas in the visible through x-ray spectral ranges deals primarily with the study of impurity line radiation or continuum radiation. Detailed knowledge of absolute intensities, temporal behavior, and spatial distributions of the emitted radiation is desired. As tokamak facilities become more complex, larger, and less accessible, there has been an increased emphasis on developing new instrumentation to provide such information in a minimum number of discharges. The availability of spatially-imaging detectors for use in the vacuum ultraviolet region (especially the intensified photodiode array) has generated the development of a variety of multichannel spectrometers for applications on tokamak facilities.

  4. High temperature power electronics for space

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.; Overton, Eric

    1991-01-01

    A high temperature electronics program at NASA Lewis Research Center focuses on dielectric and insulating materials research, development and testing of high temperature power components, and integration of the developed components and devices into a demonstrable 200 C power system, such as inverter. An overview of the program and a description of the in-house high temperature facilities along with experimental data obtained on high temperature materials are presented.

  5. Survey of the plasma electron environment of Jupiter: A view from Voyager

    NASA Technical Reports Server (NTRS)

    Scudder, J. D.; Sittler, E. C., Jr.; Bridge, H. S.

    1980-01-01

    The plasma environment within Jupiter's bow shock is considered in terms of the in situ, calibrated electron plasma measurements made between 10 eV and 5.95 keV by the Voyager plasma science experiment (PLS). Measurements were analyzed and corrected for spacecraft potential variations; the data were reduced to nearly model independent macroscopic parameters of the local electron density and temperature. It is tentatively concluded that the radial temperature profile within the plasma sheet is caused by the intermixing of two different electron populations that probably have different temporal histories and spatial paths to their local observation. The cool plasma source of the plasma sheet and spikes is probably the Io plasma torus and arrives in the plasma sheet as a result of flux tube interchange motions or other generalized transport which can be accomplished without diverting the plasma from the centrifugal equator. The hot suprathermal populations in the plasma sheet have most recently come from the sparse, hot mid-latitude "bath" of electrons which were directly observed juxtaposed to the plasma sheet.

  6. Plasma Focusing of High Energy Density Electron and Positron Beams

    SciTech Connect

    Ng, Johnny S.T.

    2000-10-09

    We present results from the SLAC E-150 experiment on plasma focusing of high energy density electron and, for the first time, positron beams. We also present results on plasma lens-induced synchrotron radiation, longitudinal dynamics of plasma focusing, and laser- and beam-plasma interactions.

  7. The Empowerment of Plasma Modeling by Fundamental Electron Scattering Data

    NASA Astrophysics Data System (ADS)

    Kushner, Mark J.

    2015-09-01

    Modeling of low temperature plasmas addresses at least 3 goals - investigation of fundamental processes, analysis and optimization of current technologies, and prediction of performance of as yet unbuilt systems for new applications. The former modeling may be performed on somewhat idealized systems in simple gases, while the latter will likely address geometrically and electromagnetically intricate systems with complex gas mixtures, and now gases in contact with liquids. The variety of fundamental electron and ion scattering data (FSD) required for these activities increases from the former to the latter, while the accuracy required of that data probably decreases. In each case, the fidelity, depth and impact of the modeling depends on the availability of FSD. Modeling is, in fact, empowered by the availability and robustness of FSD. In this talk, examples of the impact of and requirements for FSD in plasma modeling will be discussed from each of these three perspectives using results from multidimensional and global models. The fundamental studies will focus on modeling of inductively coupled plasmas sustained in Ar/Cl2 where the electron scattering from feed gases and their fragments ultimately determine gas temperatures. Examples of the optimization of current technologies will focus on modeling of remote plasma etching of Si and Si3N4 in Ar/NF3/N2/O2 mixtures. Modeling of systems as yet unbuilt will address the interaction of atmospheric pressure plasmas with liquids Work was supported by the US Dept. of Energy (DE-SC0001939), National Science Foundation (CHE-124752), and the Semiconductor Research Corp.

  8. Neoclassical Predictions of ``Electron Root'' Plasmas at HSX

    NASA Astrophysics Data System (ADS)

    Lore, Jeremy; Anderson, David; Briesemeister, Alexis; Talmadge, Joseph; Zhai, Kan; Guttenfelder, Walter; Spong, Don

    2008-11-01

    Recent neoclassical transport calculations at HSX for discharges with very peaked electron temperature profiles (Te(0)>2.5keV) show predictions of large (>400V/cm) radial electric fields in the plasma core. The existence of this ``electron root'' is due to the ion poloidal resonance with Te>>Ti, and it is predicted to have an effect on both neoclassical and anomalous transport. Calculations were made using the DKES code [1], which uses a non-momentum conserving collision operator. Initial results will be shown from the PENTA code [2] based on a moments method which recovers the effects of momentum conservation by including effects of the parallel flows. Results of plasma density and ECRH power scans will be presented as investigations into the experimental existence of the `electron root' and possible internal transport barrier formation. [1] W.I. van Rij and S.P. Hirshman, Phys. Fluids B 1, 563 (1989) [2] D.A. Spong, Phys. Plasmas 12, 056114 (2005) This work is supported by DOE Grant DE-FG02-93ER54222.

  9. Electron temperature and heat flow in the nightside Venus ionosphere

    NASA Technical Reports Server (NTRS)

    Hoegy, W. R.; Brace, L. H.; Theis, R. F.; Mayr, H. G.

    1980-01-01

    A steady-state two-dimensional heat balance model is used to analyze the night side Venusian ionospheric electron temperatures given by the Pioneer Venus orbiter electron temperature probe. The energy calculation includes the solar EUV heating at the terminator, electron cooling to ions and neutrals, and heat conduction within the ionospheric plasma. An optimum magnetic field is derived by solving for the heat flux directions which force energy conservation while constrained by the observed temperatures within the range of 80-170 deg solar zenith angle and 160-170 km. The heat flux vectors indicate a magnetic field that connects the lower night side ionosphere to the day side ionosphere, and connects the upper ionosphere to the ionosheath. The lower ionosphere is heated through conduction of heat from the dayside, and the upper ionosphere is heated by the solar wind in the ionosheath with heat flowing downward and from the nightside to the day side.

  10. Transport of electron-hole plasma in germanium

    NASA Astrophysics Data System (ADS)

    Kirch, S. J.; Wolfe, J. P.

    1986-08-01

    Time-resolved luminescence imaging techniques are used to observe the spectral and spatial evolution of laser-generated electron-hole plasma in Ge. Both pulsed and cw excitation conditions are examined above and below the critical temperature for electron-hole liquid formation, Tc(LG). For Q-switched Nd-doped yttrium aluminum garnet laser excitation, the transport behavior is qualitatively similar above and below Tc(LG), although the luminescence spectrum undergoes significant changes in this temperature range. A rapid initial expansion (v~105 cm/s) is followed by a period of slower growth which gradually reduces as the carriers recombine. The initial velocity for pulsed excitation increases monotonically as the crystal temperature is lowered and saturates near the phonon sound velocity for high-energy excitation. These observations are consistent with phonon-wind driven transport. For intense Q-switched excitation, the motion is characterized by three regimes: (1) During the laser pulse the plasma expands as a large drop with near-unity filling fraction. (2) Expansion at near-sonic velocity continues after the peak of the laser pulse due to a ``prompt'' pulse of ballistic phonons produced by the carrier thermalization process. (3) After this intense phonon wind passes the carrier distribution, the expansion velocity abruptly decreases, but the plasma continues to expand more slowly under the influence of a ``hot spot'' produced at the excitation point. The sound barrier observed on these time scales (>=30 ns) can be explained in terms of nonlinear damping of the plasma motion near the sound velocity. For cw excitation, the expansion is observed to occur at much lower velocities (v~104 cm/s). These expansion rates are much too low to require the inclusion of a drifted Fermi distribution in the spectral analysis as has been previously suggested. Instead, based upon a careful study of corresponding spectral data, an alternative explanation for these spectra is

  11. Laser electron acceleration in the prepulse produced plasma corona

    NASA Astrophysics Data System (ADS)

    Andreev, N. E.; Povarnitsyn, M. E.; Pugachev, L. P.; Levashov, P. R.

    2015-11-01

    The generation of hot electrons at grazing incidence of a subpicosecond relativistic-intense laser pulse onto the plane solid target is analyzed for the parameters of the petawatt class laser systems. We study the preplasma formation on the surface of solid Al target produced by the laser prepulses with different time structure. For modeling of the preplasma dynamics we use a wide-range two-temperature hydrodynamic model. As a result of simulations, the preplasma expansion under the action of the laser prepulse and the plasma density profiles for different contrast ratios of the nanosecond pedestal are found. These density profiles were used as the initial density distributions in 3-D PIC simulations of electron acceleration by the main P-polarized laser pulse. Results of modeling demonstrate the substantial increase of the characteristic energy and number of accelerated electrons for the grazing incidence of a subpicosecond intense laser pulse in comparison with the laser-target interaction at normal incidence.

  12. Hydrodynamic theory of diffusion in two-temperature multicomponent plasmas

    SciTech Connect

    Ramshaw, J.D.; Chang, C.H.

    1995-12-31

    Detailed numerical simulations of multicomponent plasmas require tractable expressions for species diffusion fluxes, which must be consistent with the given plasma current density J{sub q} to preserve local charge neutrality. The common situation in which J{sub q} = 0 is referred to as ambipolar diffusion. The use of formal kinetic theory in this context leads to results of formidable complexity. We derive simple tractable approximations for the diffusion fluxes in two-temperature multicomponent plasmas by means of a generalization of the hydrodynamical approach used by Maxwell, Stefan, Furry, and Williams. The resulting diffusion fluxes obey generalized Stefan-Maxwell equations that contain driving forces corresponding to ordinary, forced, pressure, and thermal diffusion. The ordinary diffusion fluxes are driven by gradients in pressure fractions rather than mole fractions. Simplifications due to the small electron mass are systematically exploited and lead to a general expression for the ambipolar electric field in the limit of infinite electrical conductivity. We present a self-consistent effective binary diffusion approximation for the diffusion fluxes. This approximation is well suited to numerical implementation and is currently in use in our LAVA computer code for simulating multicomponent thermal plasmas. Applications to date include a successful simulation of demixing effects in an argon-helium plasma jet, for which selected computational results are presented. Generalizations of the diffusion theory to finite electrical conductivity and nonzero magnetic field are currently in progress.

  13. Experimental and Theoretical Determination of Temperature in Plasmas

    SciTech Connect

    Zmerli, Besma; Ben Nessib, Nebil; Dimitrijevic, Milan S.

    2007-09-28

    When plasma is in thermodynamic equilibrium, all species have the same kinetic temperature. In practice, plasmas are generally not in equilibrium, so different temperatures can be obtained. We investigated here temperature dependence of Stark widths for neutral atom spectral lines in order to find a more precise method for scaling with temperature.

  14. Generation of anomalously energetic suprathermal electrons by an electron beam interacting with a nonuniform plasma

    SciTech Connect

    Sydorenko, D.; Kaganovich, I. D.; Chen, L.; Ventzek, P. L. G.

    2015-12-15

    Generation of anomalously energetic suprathermal electrons was observed in simulation of a high-voltage dc discharge with electron emission from the cathode. An electron beam produced by the emission interacts with the nonuniform plasma in the discharge via a two-stream instability. The energy transfer from the beam to the plasma electrons is ensured by the plasma nonuniformity. The electron beam excites plasma waves whose wavelength and phase speed gradually decrease towards anode. The waves with short wavelength near the anode accelerate plasma bulk electrons to suprathermal energies. The sheath near the anode reflects some of the accelerated electrons back into the plasma. These electrons travel through the plasma, reflect near the cathode, and enter the accelerating area again but with a higher energy than before. Such particles are accelerated to energies much higher than after the first acceleration. This mechanism plays a role in explaining earlier experimental observations of energetic suprathermal electrons in similar discharges.

  15. Nonlinear effects at the boundary of an electron plasma

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.; Shukla, P. K.

    2003-05-01

    Two solutions for nonlinear electron plasma waves propagating along a cold plasma boundary are reported. Thus, the nonlinear frequency shift caused by the harmonic generation as well as new localized nonlinear perturbations are found.

  16. The behavior of the electron plasma boundary in ultraintense laser–highly overdense plasma interaction

    SciTech Connect

    Sánchez-Arriaga, G.; Sanz, J.; Debayle, A.; Lehmann, G.

    2014-12-15

    The structural stability of the laser/plasma interaction is discussed, for the case of a linearly polarized laser beam interacting with a solid at normal incidence. Using a semi-analytical cold fluid model, the dynamics of the electron plasma boundary (EPB), usually related to the high-order harmonic generation and laser absorption, are presented. While the well-known J × B plasma oscillations at two times the laser frequency are recovered by the model, several other periodic in time stable solutions exist for exactly the same value of the physical parameters. This novel behavior highlights the importance of the laser pulse history among other factors. Some important features, such as the synchronization between the incident laser and the EPB oscillation, depend on the solution under consideration. A description of the possible types of stable oscillations in a parametric plane involving plasma density and laser amplitude is presented. The semi-analytical model is compared with particle-in-cell and semi-Lagrangian Vlasov simulations. They show that, among all the stable solutions, the plasma preferentially evolves to a state with the EPB oscillating twice faster than the laser. The effect of the plasma temperature and the existence of a ramp in the ion density profile are also discussed.

  17. Helical temperature perturbations associated with tearing modes in tokamak plasmas

    SciTech Connect

    Fitzpatrick, R.

    1994-06-01

    An investigation is made into the electron temperature perturbations associated with tearing modes in tokamak plasmas, with a view to determining the mode structure using Electron Cyclotron Emission (ECE) data. It is found that there is a critical magnetic island width below which the conventional picture where the temperature is flattened inside the separatrix is invalid. This effect comes about because of the stagnation of magnetic field lines in the vicinity of the rational surface and the finite parallel thermal conductivity of the plasma. For islands whose widths lie below the critical value there is no flattening of the electron temperature inside the separatrix. Such islands have quite different ECE signatures to conventional magnetic islands. In fact the two island types could, in principle, be differentiated experimentally. It should also be possible to map out the outer ideal magnetohydrodynamical eigenfunctions using ECE data. Islands whose widths are much less than the critical value are not destabilized by the perturbed bootstrap current, unlike conventional magnetic islands. This effect is found to have a number of very interesting consequences and may, indeed, provide an explanation for some puzzling experimental results regarding error field induced magnetic reconnection. All islands whose widths are much greater than the critical width possess a boundary layer on the separatrix which enables heat to be transported from one side of the island to the other via the X-point region. The structure of this boundary layer is described in some detail. Finally, the critical island width is found to be fairly substantial in conventional tokamak plasmas, provided that the long mean free path nature of parallel heat transport and the anomalous nature of perpendicular heat transport are taken into account in the calculation.

  18. Characterization of electron temperature by simulating a multicusp ion source

    NASA Astrophysics Data System (ADS)

    Yeon, Yeong Heum; Ghergherehchi, Mitra; Kim, Sang Bum; Jun, Woo Jung; Lee, Jong Chul; Mohamed Gad, Khaled Mohamed; Namgoong, Ho; Chai, Jong Seo

    2016-12-01

    Multicusp ion sources are used in cyclotrons and linear accelerators to produce high beam currents. The structure of a multicusp ion source consists of permanent magnets, filaments, and an anode body. The configuration of the array of permanent magnets, discharge voltage of the plasma, extraction bias voltage, and structure of the multicusp ion source body decide the quality of the beam. The electrons are emitted from the filament by thermionic emission. The emission current can be calculated from thermal information pertaining to the filament, and from the applied voltage and current. The electron trajectories were calculated using CST Particle Studio to optimize the plasma. The array configuration of the permanent magnets decides the magnetic field inside the ion source. The extraction bias voltage and the structure of the multicusp ion source body decide the electric field. Optimization of the electromagnetic field was performed with these factors. CST Particle Studio was used to calculate the electron temperature with a varying permanent magnet array. Four types of permanent magnet array were simulated to optimize the electron temperature. It was found that a 2-layer full line cusp field (with inverse field) produced the best electron temperature control behavior.

  19. Plasma formation and temperature measurement during single-bubble cavitation

    NASA Astrophysics Data System (ADS)

    Flannigan, David J.; Suslick, Kenneth S.

    2005-03-01

    Single-bubble sonoluminescence (SBSL) results from the extreme temperatures and pressures achieved during bubble compression; calculations have predicted the existence of a hot, optically opaque plasma core with consequent bremsstrahlung radiation. Recent controversial reports claim the observation of neutrons from deuterium-deuterium fusion during acoustic cavitation. However, there has been previously no strong experimental evidence for the existence of a plasma during single- or multi-bubble sonoluminescence. SBSL typically produces featureless emission spectra that reveal little about the intra-cavity physical conditions or chemical processes. Here we report observations of atomic (Ar) emission and extensive molecular (SO) and ionic (O2+) progressions in SBSL spectra from concentrated aqueous H2SO4 solutions. Both the Ar and SO emission permit spectroscopic temperature determinations, as accomplished for multi-bubble sonoluminescence with other emitters. The emissive excited states observed from both Ar and O2+ are inconsistent with any thermal process. The Ar excited states involved are extremely high in energy (>13eV) and cannot be thermally populated at the measured Ar emission temperatures (4,000-15,000K) the ionization energy of O2 is more than twice its bond dissociation energy, so O2+ likewise cannot be thermally produced. We therefore conclude that these emitting species must originate from collisions with high-energy electrons, ions or particles from a hot plasma core.

  20. Plasma formation and temperature measurement during single-bubble cavitation.

    PubMed

    Flannigan, David J; Suslick, Kenneth S

    2005-03-03

    Single-bubble sonoluminescence (SBSL) results from the extreme temperatures and pressures achieved during bubble compression; calculations have predicted the existence of a hot, optically opaque plasma core with consequent bremsstrahlung radiation. Recent controversial reports claim the observation of neutrons from deuterium-deuterium fusion during acoustic cavitation. However, there has been previously no strong experimental evidence for the existence of a plasma during single- or multi-bubble sonoluminescence. SBSL typically produces featureless emission spectra that reveal little about the intra-cavity physical conditions or chemical processes. Here we report observations of atomic (Ar) emission and extensive molecular (SO) and ionic (O2+) progressions in SBSL spectra from concentrated aqueous H2SO4 solutions. Both the Ar and SO emission permit spectroscopic temperature determinations, as accomplished for multi-bubble sonoluminescence with other emitters. The emissive excited states observed from both Ar and O2+ are inconsistent with any thermal process. The Ar excited states involved are extremely high in energy (>13 eV) and cannot be thermally populated at the measured Ar emission temperatures (4,000-15,000 K); the ionization energy of O2 is more than twice its bond dissociation energy, so O2+ likewise cannot be thermally produced. We therefore conclude that these emitting species must originate from collisions with high-energy electrons, ions or particles from a hot plasma core.

  1. [Electronic rectal temperature measurement. A clinical trial].

    PubMed

    Ottesen, S; Nielsen, F T; Lund, H

    1993-05-24

    Rectal measurement of body temperature with an electronic device (Ivac) was compared to measurement with mercury thermometers in 157 adult patients on a medical ward. The electronic thermometers were less accurate, giving 3.6 times as many febrile patients. This was reduced to 1.6 after thermometer calibration. It is necessary to make regular calibrations of Ivac thermometers.

  2. The effect of quantum correction on plasma electron heating in ultraviolet laser interaction

    NASA Astrophysics Data System (ADS)

    Zare, S.; Yazdani, E.; Sadighi-Bonabi, R.; Anvari, A.; Hora, H.

    2015-04-01

    The interaction of the sub-picosecond UV laser in sub-relativistic intensities with deuterium is investigated. At high plasma temperatures, based on the quantum correction in the collision frequency, the electron heating and the ion block generation in plasma are studied. It is found that due to the quantum correction, the electron heating increases considerably and the electron temperature uniformly reaches up to the maximum value of 4.91 × 107 K. Considering the quantum correction, the electron temperature at the laser initial coupling stage is improved more than 66.55% of the amount achieved in the classical model. As a consequence, by the modified collision frequency, the ion block is accelerated quicker with higher maximum velocity in comparison with the one by the classical collision frequency. This study proves the necessity of considering a quantum mechanical correction in the collision frequency at high plasma temperatures.

  3. The effect of quantum correction on plasma electron heating in ultraviolet laser interaction

    SciTech Connect

    Zare, S.; Sadighi-Bonabi, R. Anvari, A.; Yazdani, E.; Hora, H.

    2015-04-14

    The interaction of the sub-picosecond UV laser in sub-relativistic intensities with deuterium is investigated. At high plasma temperatures, based on the quantum correction in the collision frequency, the electron heating and the ion block generation in plasma are studied. It is found that due to the quantum correction, the electron heating increases considerably and the electron temperature uniformly reaches up to the maximum value of 4.91 × 10{sup 7 }K. Considering the quantum correction, the electron temperature at the laser initial coupling stage is improved more than 66.55% of the amount achieved in the classical model. As a consequence, by the modified collision frequency, the ion block is accelerated quicker with higher maximum velocity in comparison with the one by the classical collision frequency. This study proves the necessity of considering a quantum mechanical correction in the collision frequency at high plasma temperatures.

  4. A generalized plasma dispersion function for electron damping in tokamak plasmas

    SciTech Connect

    Berry, L. A.; Jaeger, E. F.; Phillips, C. K.; Lau, C. H.; Bertelli, N.; Green, D. L.

    2016-10-14

    Radio frequency wave propagation in finite temperature, magnetized plasmas exhibits a wide range of physics phenomena. The plasma response is nonlocal in space and time, and numerous modes are possible with the potential for mode conversions and transformations. Additionally, diffraction effects are important due to finite wavelength and finite-size wave launchers. Multidimensional simulations are required to describe these phenomena, but even with this complexity, the fundamental plasma response is assumed to be the uniform plasma response with the assumption that the local plasma current for a Fourier mode can be described by the Stix conductivity. But, for plasmas with non-uniform magnetic fields, the wave vector itself is nonlocal. When resolved into components perpendicular (k ) and parallel (k ||) to the magnetic field, locality of the parallel component can easily be violated when the wavelength is large. The impact of this inconsistency is that estimates of the wave damping can be incorrect (typically low) due to unresolved resonances. For the case of ion cyclotron damping, this issue has already been addressed by including the effect of parallel magnetic field gradients. In this case, a modified plasma response (Z function) allows resonance broadening even when k || = 0, and this improves the convergence and accuracy of wave simulations. In our paper, we extend this formalism to include electron damping and find improved convergence and accuracy for parameters where electron damping is dominant, such as high harmonic fast wave heating in the NSTX-U tokamak, and helicon wave launch for off-axis current drive in the DIII-D tokamak.

  5. A generalized plasma dispersion function for electron damping in tokamak plasmas

    DOE PAGES

    Berry, L. A.; Jaeger, E. F.; Phillips, C. K.; ...

    2016-10-14

    Radio frequency wave propagation in finite temperature, magnetized plasmas exhibits a wide range of physics phenomena. The plasma response is nonlocal in space and time, and numerous modes are possible with the potential for mode conversions and transformations. Additionally, diffraction effects are important due to finite wavelength and finite-size wave launchers. Multidimensional simulations are required to describe these phenomena, but even with this complexity, the fundamental plasma response is assumed to be the uniform plasma response with the assumption that the local plasma current for a Fourier mode can be described by the Stix conductivity. But, for plasmas with non-uniformmore » magnetic fields, the wave vector itself is nonlocal. When resolved into components perpendicular (k ) and parallel (k ||) to the magnetic field, locality of the parallel component can easily be violated when the wavelength is large. The impact of this inconsistency is that estimates of the wave damping can be incorrect (typically low) due to unresolved resonances. For the case of ion cyclotron damping, this issue has already been addressed by including the effect of parallel magnetic field gradients. In this case, a modified plasma response (Z function) allows resonance broadening even when k || = 0, and this improves the convergence and accuracy of wave simulations. In our paper, we extend this formalism to include electron damping and find improved convergence and accuracy for parameters where electron damping is dominant, such as high harmonic fast wave heating in the NSTX-U tokamak, and helicon wave launch for off-axis current drive in the DIII-D tokamak.« less

  6. A generalized plasma dispersion function for electron damping in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Berry, L. A.; Jaeger, E. F.; Phillips, C. K.; Lau, C. H.; Bertelli, N.; Green, D. L.

    2016-10-01

    Radio frequency wave propagation in finite temperature, magnetized plasmas exhibits a wide range of physics phenomena. The plasma response is nonlocal in space and time, and numerous modes are possible with the potential for mode conversions and transformations. In addition, diffraction effects are important due to finite wavelength and finite-size wave launchers. Multidimensional simulations are required to describe these phenomena, but even with this complexity, the fundamental plasma response is assumed to be the uniform plasma response with the assumption that the local plasma current for a Fourier mode can be described by the "Stix" conductivity. However, for plasmas with non-uniform magnetic fields, the wave vector itself is nonlocal. When resolved into components perpendicular (k⊥) and parallel (k||) to the magnetic field, locality of the parallel component can easily be violated when the wavelength is large. The impact of this inconsistency is that estimates of the wave damping can be incorrect (typically low) due to unresolved resonances. For the case of ion cyclotron damping, this issue has already been addressed by including the effect of parallel magnetic field gradients. In this case, a modified plasma response (Z function) allows resonance broadening even when k|| = 0, and this improves the convergence and accuracy of wave simulations. In this paper, we extend this formalism to include electron damping and find improved convergence and accuracy for parameters where electron damping is dominant, such as high harmonic fast wave heating in the NSTX-U tokamak, and helicon wave launch for off-axis current drive in the DIII-D tokamak.

  7. Ponderomotive perturbations of low density low-temperature plasma under laser Thomson scattering diagnostics

    NASA Astrophysics Data System (ADS)

    Shneider, Mikhail N.

    2017-10-01

    The ponderomotive perturbation in the interaction region of laser radiation with a low density and low-temperature plasma is considered. Estimates of the perturbation magnitude are determined from the plasma parameters, geometry, intensity, and wavelength of laser radiation. It is shown that ponderomotive perturbations can lead to large errors in the electron density when measured using Thomson scattering.

  8. Double electrostatic probe for measuring density, temperature, and velocity of a flowing plasma

    NASA Technical Reports Server (NTRS)

    Chubb, D. L.

    1973-01-01

    A method for obtaining plasma electron temperature and density, as well as the Mach number and flow velocity from the current-voltage characteristic of a flat-faced double probe, is presented. Calculated momentum fluxes of a flowing argon plasma obtained with this probe are compared with experimentally determined momentum fluxes. Reasonable agreement is obtained.

  9. Atlas and wavenumber tables for the visible part of the electronic-vibro-rotational D2 spectrum emitted by low-temperature plasma

    NASA Astrophysics Data System (ADS)

    Lavrov, Boris P.; Umrikhin, Ivan S.

    2016-10-01

    The visible part (≈ 419-696 nm) of the multiline electronic-vibro-rotational (rovibronic) emission spectrum of the D2 molecule was recorded with a moderate resolution mainly determined by Doppler broadening of spectral lines (the observed line widths are equal to 0.0122(4) nm throughout the wavelength range under study). After the numerical deconvolution of the recorded intensity distributions and proper spectrometer calibrations, the new set of wavenumber values for rovibronic spectral lines has been obtained. It is shown that these new data are significantly more precise than experimental wavenumber values currently published for the visible part of the D2 spectrum, except for the fragmentary results of our high-resolution experiments (Phys. Rev. A, 2012). The assignments of the triplet rovibronic lines are verified by means of the optimizational technique based on two general principles: Rydberg-Ritz and maximum likelihood (J. Phys. B, 2008). Final results (reported in the on-line supplement material) include an atlas and accompanying tables. The atlas is divided into 158 sections (each section covers about 1.5 nm) containing images of the focal plane of the spectrometer and intensity distributions in linear and logarithmic scales. The tables contain wavenumber and relative intensity values for 11 941 spectral lines together with the available and new line assignments for the D2 and HD molecules.

  10. Picosecond imaging of low-density plasmas by electron deflectometry.

    PubMed

    Centurion, M; Reckenthaeler, P; Krausz, F; Fill, E E

    2009-02-15

    We have imaged optical-field ionized plasmas with electron densities as low as 10(13) cm(-3) on a picosecond timescale using ultrashort electron pulses. Electric fields generated by the separation of charges are imprinted on a 20 keV probe electron pulse and reveal a cloud of electrons expanding away from a positively charged plasma core. Our method allows for a direct measurement of the electron energy required to escape the plasma and the total charge. Simulations reproduce the main features of the experiment and allow determination of the energy of the electrons.

  11. Observation of the loss of pre-disruptive runaway electrons in KSTAR ohmic plasma disruptions

    NASA Astrophysics Data System (ADS)

    Cheon, MunSeong; Kim, Junghee; An, YoungHwa; Seo, Dongcheol; Kim, Hyunseok

    2016-12-01

    A newly-developed fast neutron detector revealed a close relationship between the loss of pre-disruptive runaway electrons and the plasma disruption in KSTAR ohmic plasmas. It is observed that a burst of photoneutrons is generated exactly before the start of thermal quenches, indicating a bunch of runaway electrons which had existed before the disruption impacts the first wall at the time. The loss of runaway electrons could be identified also as a decrease in the measured electron temperature, forming a typical two-stage thermal quench trace. From the MHD pattern in the neutron signal during a low-q disruption, it could be identified that pre-disruptive runaway electrons are localized in the plasma, especially on the q  =  2 drift surface. These new findings suggest the pre-disruptive runaway electrons might play an important role in the plasma disruption mechanism.

  12. Deep Trek High Temperature Electronics Project

    SciTech Connect

    Bruce Ohme

    2007-07-31

    This report summarizes technical progress achieved during the cooperative research agreement between Honeywell and U.S. Department of Energy to develop high-temperature electronics. Objects of this development included Silicon-on-Insulator (SOI) wafer process development for high temperature, supporting design tools and libraries, and high temperature integrated circuit component development including FPGA, EEPROM, high-resolution A-to-D converter, and a precision amplifier.

  13. Ion energy distributions, electron temperatures, and electron densities in Ar, Kr, and Xe pulsed discharges

    SciTech Connect

    Shin, Hyungjoo; Zhu Weiye; Economou, Demetre J.; Donnelly, Vincent M.

    2012-05-15

    Ion energy distributions (IEDs) were measured near the edge of Faraday-shielded, inductively coupled pulsed plasmas in Ar, Kr, or Xe gas, while applying a synchronous dc bias on a boundary electrode, late in the afterglow. The magnitudes of the full width at half maximum of the IEDs were Xe > Kr > Ar, following the order of the corresponding electron temperatures in the afterglow, T{sub e}(Xe) > T{sub e}(Kr) > T{sub e}(Ar). The measured decays of T{sub e} with time in the afterglow were in excellent agreement with predictions from a global model. Measured time-resolved electron and positive ion densities near the plasma edge did not decay appreciably, even in the 80 {mu}s long afterglow. This was attributed to transport of ions and electrons from the higher density central region of the plasma to the edge region, balancing the loss of plasma due to diffusion. This provides a convenient means of maintaining a relatively constant plasma density in the afterglow during processing using pulsed plasmas.

  14. Measuring electron temperature in the extended corona

    NASA Technical Reports Server (NTRS)

    Hassler, Donald M.; Gardner, L. D.; Kohl, John L.

    1992-01-01

    A technique for measuring electron temperature in the extended corona from the line profile of the electron scattered component of coronal H I Ly alpha produced by Thomson scattering of chromospheric Ly alpha emission is discussed. Because of the high thermal velocity of electrons at coronal temperatures (approximately 6800 km/s at T(sub e) = 1,500,000 K) the effect of nonthermal velocities and solar wind flows on the electron velocity distribution are negligible. However, the low electron mass which is responsible for the high thermal velocity also results in a very wide profile (approximately equal to 50 A). This wide profile, together with an intensity