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Sample records for dense hydrogen plasmas

  1. 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.

  2. Resonances in positron-hydrogen scattering in dense quantum plasmas

    SciTech Connect

    Jiang, Zishi; Zhang, Yong-Zhi; Kar, Sabyasachi

    2015-05-15

    We have investigated the S-wave resonance states in positron-hydrogen system embedded in dense quantum plasmas using Hylleraas-type wave functions within the framework of the stabilization method. The effect of quantum plasmas has been incorporated using the exponential-cosine-screened Coulomb (modified Yukawa-type) potential. Resonance parameters (both position and width) below the Ps n = 2 threshold are reported as functions of plasma screening parameters.

  3. Positron scattering from hydrogen atom embedded in dense quantum plasma

    SciTech Connect

    Bhattacharya, Arka; Kamali, M. Z. M.; Ghoshal, Arijit; Ratnavelu, K.

    2013-08-15

    Scattering of positrons from the ground state of hydrogen atoms embedded in dense quantum plasma has been investigated by applying a formulation of the three-body collision problem in the form of coupled multi-channel two-body Lippmann-Schwinger equations. The interactions among the charged particles in dense quantum plasma have been represented by exponential cosine-screened Coulomb potentials. Variationally determined hydrogenic wave function has been employed to calculate the partial-wave scattering amplitude. Plasma screening effects on various possible mode of fragmentation of the system e{sup +}+H(1s) during the collision, such as 1s→1s and 2s→2s elastic collisions, 1s→2s excitation, positronium formation, elastic proton-positronium collisions, have been reported in the energy range 13.6-350 eV. Furthermore, a comparison has been made on the plasma screening effect of a dense quantum plasma with that of a weakly coupled plasma for which the plasma screening effect has been represented by the Debye model. Our results for the unscreened case are in fair agreement with some of the most accurate results available in the literature.

  4. Modeling the Spectra of Dense Hydrogen Plasmas: Beyond Occupation Probability

    NASA Astrophysics Data System (ADS)

    Gomez, T. A.; Montgomery, M. H.; Nagayama, T.; Kilcrease, D. P.; Winget, D. E.

    2017-03-01

    Accurately measuring the masses of white dwarf stars is crucial in many astrophysical contexts (e.g., asteroseismology and cosmochronology). These masses are most commonly determined by fitting a model atmosphere to an observed spectrum; this is known as the spectroscopic method. However, for cases in which more than one method may be employed, there are well known discrepancies between masses determined by the spectroscopic method and those determined by astrometric, dynamical, and/or gravitational-redshift methods. In an effort to resolve these discrepancies, we are developing a new model of hydrogen in a dense plasma that is a significant departure from previous models. Experiments at Sandia National Laboratories are currently underway to validate these new models, and we have begun modifications to incorporate these models into stellar-atmosphere codes.

  5. Energy loss of heavy ions in a dense hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Dietrich, K.-G.; Hoffmann, D. H. H.; Wahl, H.; Haas, C. R.; Kunze, H.; Brandenburg, W.; Noll, R.

    1990-12-01

    The energy loss of heavy ions with an energy of 1.4 MeV/u in a hydrogen plasma has been measured. A 20 cm long z-pinch has been used as plasma target. Our data show a strong enhancement of the stopping power of the plasma compared to that of a cold gas with equal density. The results completely confirm the predictions of the standard stopping power model.

  6. Plasma-screening effects on the electron-impact excitation of hydrogenic ions in dense plasmas

    NASA Technical Reports Server (NTRS)

    Jung, Young-Dae

    1993-01-01

    Plasma-screening effects are investigated on electron-impact excitation of hydrogenic ions in dense plasmas. Scaled cross sections Z(exp 4) sigma for 1s yields 2s and 1s yields 2p are obtained for a Debye-Hueckel model of the screened Coulomb interaction. Ground and excited bound wave functions are modified in the screened Coulomb potential (Debye-Hueckel model) using the Ritz variation method. The resulting atomic wave functions and their eigenenergies agree well with the numerical and high-order perturbation theory calculations for the interesting domain of the Debye length not less than 10. The Born approximation is used to describe the continuum states of the projectile electron. Plasma screening effects on the atomic electrons cannot be neglected in the high-density cases. Including these effects, the cross sections are appreciably increased for 1s yields 2s transitions and decreased for 1s yields 2p transitions.

  7. Dynamics of the fully stripped ion-hydrogen atom charge exchange process in dense quantum plasmas

    SciTech Connect

    Zhang, Ling-yu; Wan, Jiang-feng; Zhao, Xiao-ying; Xiao, Guo-qing; Duan, Wen-shan; Qi, Xin; Yang, Lei

    2014-09-15

    The plasma screening effects of dense quantum plasmas on charge exchange processes of a fully stripped ion colliding with a hydrogen atom are studied by the classical trajectory Monte Carlo method. The inter-particle interactions are described by the exponential cosine-screened Coulomb potentials. It is found that in weak screening conditions, cross sections increase with the increase of the ionic charge Z. However, in strong screening conditions, the dependence of cross sections on the ionic charge is related to the incident particle energy. At high energies, cross sections show a linear increase with the increase of Z, whereas at low energies, cross sections for Z≥4 become approximately the same. The He{sup 2+} and C{sup 6+} impacting charge exchange cross sections in dense quantum plasmas are also compared with those in weakly coupled plasmas. The interactions are described by the static screened Coulomb potential. It is found that for both He{sup 2+} and C{sup 6+}, the oscillatory screening effects of dense quantum plasmas are almost negligible in weak screening conditions. However, in strong screening conditions, the oscillatory screening effects enhance the screening effects of dense quantum plasmas, and the enhancement becomes more and more significant with the increase of the screening parameter and the ionic charge.

  8. Positron impact excitations of hydrogen atom embedded in dense quantum plasmas: Formation of Rydberg atoms

    SciTech Connect

    Rej, Pramit; Ghoshal, Arijit

    2014-11-15

    Formation of Rydberg atoms due to 1 s → nlm excitations of hydrogen by positron impact, for arbitrary n, l, m, in dense quantum plasma has been investigated using a distorted wave theory which includes screened dipole polarization potential. The interactions among the charged particles in the plasma have been represented by exponential cosine-screened Coulomb potentials. Making use of a simple variationally determined hydrogen wave function, it has been possible to obtain the distorted wave scattering amplitude in a closed analytical form. A detailed study has been made to explore the structure of differential and total cross sections in the energy range 20–300 eV of incident positron. For the unscreened case, our results agree nicely with some of the most accurate results available in the literature. To the best of our knowledge, such a study on the differential and total cross sections for 1 s → nlm inelastic positron-hydrogen collisions in dense quantum plasma is the first reported in the literature.

  9. Influence of dense quantum plasmas on fine-structure splitting of Lyman doublets of hydrogenic systems

    SciTech Connect

    De, Madhab Ray, Debasis

    2015-05-15

    Relativistic calculations are performed to study the effects of oscillatory quantum plasma screening on the fine-structure splitting between the components of Lyman-α and β line doublets of atomic hydrogen and hydrgen-like argon ion within dense quantum plasmas, where the effective two-body (electron–nucleus) interaction is modeled by the Shukla–Eliasson oscillatory exponential cosine screened-Coulomb potential. The numerical solutions of the radial Dirac equation for the quantum plasma-embedded atomic systems reveal that the oscillatory quantum screening effect suppresses the doublet (energy) splitting substantially and the suppression becomes more prominent at large quantum wave number k{sub q}. In the absence of the oscillatory cosine screening term, much larger amount of suppression is noticed at larger values of k{sub q}, and the corresponding results represent the screening effect of an exponential screened-Coulomb two-body interaction. The Z{sup 4} scaling of the Lyman doublet splitting in low-Z hydrogen isoelectronic series of ions in free space is violated in dense quantum plasma environments. The relativistic data for the doublet splitting in the zero screening (k{sub q} = 0) case are in very good agreement with the NIST reference data, with slight discrepancies (∼0.2%) arising from the neglect of the quantum electrodynamic effects.

  10. Influence of dense quantum plasmas on fine-structure splitting of Lyman doublets of hydrogenic systems

    NASA Astrophysics Data System (ADS)

    De, Madhab; Ray, Debasis

    2015-05-01

    Relativistic calculations are performed to study the effects of oscillatory quantum plasma screening on the fine-structure splitting between the components of Lyman-α and β line doublets of atomic hydrogen and hydrgen-like argon ion within dense quantum plasmas, where the effective two-body (electron-nucleus) interaction is modeled by the Shukla-Eliasson oscillatory exponential cosine screened-Coulomb potential. The numerical solutions of the radial Dirac equation for the quantum plasma-embedded atomic systems reveal that the oscillatory quantum screening effect suppresses the doublet (energy) splitting substantially and the suppression becomes more prominent at large quantum wave number kq. In the absence of the oscillatory cosine screening term, much larger amount of suppression is noticed at larger values of kq, and the corresponding results represent the screening effect of an exponential screened-Coulomb two-body interaction. The Z4 scaling of the Lyman doublet splitting in low-Z hydrogen isoelectronic series of ions in free space is violated in dense quantum plasma environments. The relativistic data for the doublet splitting in the zero screening (kq = 0) case are in very good agreement with the NIST reference data, with slight discrepancies (˜0.2%) arising from the neglect of the quantum electrodynamic effects.

  11. Quantum-statistical T-matrix approach to line broadening of hydrogen in dense plasmas

    SciTech Connect

    Lorenzen, Sonja; Wierling, August; Roepke, Gerd; Reinholz, Heidi; Zammit, Mark C.; Fursa, Dmitry V.; Bray, Igor

    2010-10-29

    The electronic self-energy {Sigma}{sup e} is an important input in a quantum-statistical theory for spectral line profile calculations. It describes the influence of plasma electrons on bound state properties. In dense plasmas, the effect of strong, i.e. close, electron-emitter collisions can be considered by three-particle T-matrix diagrams. These digrams are approximated with the help of an effective two-particle T-matrix, which is obtained from convergent close-coupling calculations with Debye screening. A comparison with other theories is carried out for the 2p level of hydrogen at k{sub B}T = 1 eV and n{sub e} = 2{center_dot}10{sup 23} m{sup -3}, and results are given for n{sub e} = 1{center_dot}10{sup 25} m{sup -3}.

  12. Atoms in dense plasmas

    SciTech Connect

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs.

  13. Conductive dense hydrogen

    NASA Astrophysics Data System (ADS)

    Eremets, M.; Troyan, I.

    2012-12-01

    Hydrogen at ambient pressures and low temperatures forms a molecular crystal which is expected to display metallic properties under megabar pressures. This metal is predicted to be superconducting with a very high critical temperature Tc of 200-400 K. The superconductor may potentially be recovered metastably at ambient pressures, and it may acquire a new quantum state as a metallic superfluid and a superconducting superfluid. Recent experiments performed at low temperatures T < 100 K showed that at record pressures of 300 GPa, hydrogen remains in the molecular state and is an insulator with a band gap of appr 2 eV. Given our current experimental and theoretical understanding, hydrogen is expected to become metallic at pressures of 400-500 GPa, beyond the current limits of static pressures achievable using diamond anvil cells. We found that at room temperature and pressure > 220 GPa, new Raman modes arose, providing evidence for the transformation to a new opaque and electrically conductive phase IV. Above 260 GPa, in the next phase V, hydrogen reflected light well. Its resistance was nearly temperature-independent over a wide temperature range, down to 30 K, indicating that the hydrogen was metallic. Releasing the pressure induced the metallic phase to transform directly into molecular hydrogen with significant hysteresis at 200 GPa and 295 K. These data were published in our paper: M. I. Eremets and I. A. Troyan "Conductive dense hydrogen." Nature Materials 10: 927-931. We will present also new results on hydrogen: phase diagram with phases IV and V determined in P,T domain up to 300 GPa and 350 K. We will also discuss possible structures of phase IV based on our Raman and infrared measurements up to 300 GPa.

  14. Spectral line shapes using the dicenter approach for dense hot plasmas: hydrogen and helium-like lines.

    NASA Astrophysics Data System (ADS)

    Sauvan, P.; Leboucher-Dalimier, E.; Angelo, P.; Derfoul, H.; Ceccotti, T.; Poquerusse, A.; Calisti, A.; Talin, B.

    2000-05-01

    This paper reports on the spectral line shape of hydrogen and helium-like lines relevant to the quasi-static dicenter model. This treatment is justified for hot dense, moderate Z plasmas. The code IDEFIX developed for the quasi-static dicenter model involves a self-consistent description of the interactions and of the radiative properties. Strong dependence of the transition energies and of the dipole moments on the interionic separation are pointed out and novel density-dependent spectroscopic features such as asymmetries, satellite-like features, molecular transitions are exhibited. The theoretical spectra presented are discussed in connection with experimental results where these exist.

  15. Microfield dynamics in dense hydrogen plasmas with high-Z impurities

    NASA Astrophysics Data System (ADS)

    Hau-Riege, Stefan P.; Weisheit, Jon

    2017-01-01

    We use large-scale classical molecular dynamics to determine microfield properties for several dense plasma mixtures. By employing quantum statistical potentials (QSPs) to regularize the Coulomb interaction, our simulations follow motions of electrons as well as ions for times long enough to track relaxation phenomena involving both types of particles. Coulomb coupling, relative to temperature, of different pairs of species in the hot, dense matter being simulated ranges from weak to strong. We first study the effect of such coupling differences, along with composition and QSP differences, on the roles of electrons and various mixture components in determining probability distributions of instantaneous, total microfields experienced by the ions. Then, we address two important dynamical questions: (1) How is the quasistatic part of the total field to be extracted from the time-dependent simulation data? (2) Under what conditions does the commonly used approximation of ions with fixed Yukawa-like screening by free electrons accurately describe quasistatic fields? We identify a running, short-time average of the total field at each ion as its slowly evolving, quasistatic part. We consider several ways to specify the averaging interval, and note the influence of ion dynamics in this issue. When all species are weakly coupled, the quasistatic fields have probability distributions agreeing well with those we obtain from simulations of Yukawa-screened ions. However, agreement deteriorates as the coupling between high-Z ions increases well beyond unity, principally because the Yukawa model tends to underestimate the true screening of close high-Z pairs. Examples of this fact are given, and some consequences for the high-field portions of probability distributions are discussed.

  16. Dense Plasma Focus Modeling

    SciTech Connect

    Li, Hui; Li, Shengtai; Jungman, Gerard; Hayes-Sterbenz, Anna Catherine

    2016-08-31

    The mechanisms for pinch formation in Dense Plasma Focus (DPF) devices, with the generation of high-energy ions beams and subsequent neutron production over a relatively short distance, are not fully understood. Here we report on high-fidelity 2D and 3D numerical magnetohydrodynamic (MHD) simulations using the LA-COMPASS code to study the pinch formation dynamics and its associated instabilities and neutron production.

  17. Conductive dense hydrogen.

    PubMed

    Eremets, M I; Troyan, I A

    2011-11-13

    Molecular hydrogen is expected to exhibit metallic properties under megabar pressures. This metal is predicted to be superconducting with a very high critical temperature, T(c), of 200-400 K, and it may acquire a new quantum state as a metallic superfluid and a superconducting superfluid. It may potentially be recovered metastably at ambient pressures. However, experiments carried out at low temperatures, T<100 K, showed that at record pressures of 300 GPa, hydrogen remains in the molecular insulating state. Here we report on the transformation of normal molecular hydrogen at room temperature (295 K) to a conductive and metallic state. At 200 GPa the Raman frequency of the molecular vibron strongly decreased and the spectral width increased, evidencing a strong interaction between molecules. Deuterium behaved similarly. Above 220 GPa, hydrogen became opaque and electrically conductive. At 260-270 GPa, hydrogen transformed into a metal as the conductance of hydrogen sharply increased and changed little on further pressurizing up to 300 GPa or cooling to at least 30 K; and the sample reflected light well. The metallic phase transformed back at 295 K into molecular hydrogen at 200 GPa. This significant hysteresis indicates that the transformation of molecular hydrogen into a metal is accompanied by a first-order structural transition presumably into a monatomic liquid state. Our findings open an avenue for detailed and comprehensive studies of metallic hydrogen.

  18. Conductive dense hydrogen

    NASA Astrophysics Data System (ADS)

    Eremets, M. I.; Troyan, I. A.

    2011-12-01

    Molecular hydrogen is expected to exhibit metallic properties under megabar pressures. This metal is predicted to be superconducting with a very high critical temperature, Tc, of 200-400 K (ref. ), and it may acquire a new quantum state as a metallic superfluid and a superconducting superfluid. It may potentially be recovered metastably at ambient pressures. However, experiments carried out at low temperatures, T<100 K (refs , ), showed that at record pressures of 300 GPa, hydrogen remains in the molecular insulating state. Here we report on the transformation of normal molecular hydrogen at room temperature (295 K) to a conductive and metallic state. At 200 GPa the Raman frequency of the molecular vibron strongly decreased and the spectral width increased, evidencing a strong interaction between molecules. Deuterium behaved similarly. Above 220 GPa, hydrogen became opaque and electrically conductive. At 260-270 GPa, hydrogen transformed into a metal as the conductance of hydrogen sharply increased and changed little on further pressurizing up to 300 GPa or cooling to at least 30 K and the sample reflected light well. The metallic phase transformed back at 295 K into molecular hydrogen at 200 GPa. This significant hysteresis indicates that the transformation of molecular hydrogen into a metal is accompanied by a first-order structural transition presumably into a monatomic liquid state. Our findings open an avenue for detailed and comprehensive studies of metallic hydrogen.

  19. Theory of dense hydrogen

    NASA Technical Reports Server (NTRS)

    Chakravarty, S.; Rose, J. H.; Wood, D.; Ashcroft, N. W.

    1981-01-01

    Equations of state for molecular and metallic hydrogen are calculated in an accurate and comparable manner by using the density-functional method applied to static lattices. By isolating the electronic energies in this way, attention can be drawn to the relative importance of the protonic degrees of freedom. From the equation-of-state results it can be concluded that a remnant molecular pairing is preferred in a band-overlap metallic state, complete dissociation occurring only at very high densities. An accurate determination of the pressure needed to achieve complete dissociation is shown to require a self-consistent treatment of electron and proton degrees of freedom.

  20. Parametric bleaching of dense plasmas

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Ramazashvili, R. R.

    1981-11-01

    A mechanism is proposed for the nonlinear bleaching of a dense plasma slab. In this new mechanism, the electromagnetic wave incident on the plasma decays into plasma waves and then reappears as a result of the coalescence of the plasma waves at the second boundary of the slab.

  1. Resolving Ultrafast Heating of Dense Cryogenic Hydrogen

    NASA Astrophysics Data System (ADS)

    Zastrau, U.; Sperling, P.; Harmand, M.; Becker, A.; Bornath, T.; Bredow, R.; Dziarzhytski, S.; Fennel, T.; Fletcher, L. B.; Förster, E.; Göde, S.; Gregori, G.; Hilbert, V.; Hochhaus, D.; Holst, B.; Laarmann, T.; Lee, H. J.; Ma, T.; Mithen, J. P.; Mitzner, R.; Murphy, C. D.; Nakatsutsumi, M.; Neumayer, P.; Przystawik, A.; Roling, S.; Schulz, M.; Siemer, B.; Skruszewicz, S.; Tiggesbäumker, J.; Toleikis, S.; Tschentscher, T.; White, T.; Wöstmann, M.; Zacharias, H.; Döppner, T.; Glenzer, S. H.; Redmer, R.

    2014-03-01

    We report on the dynamics of ultrafast heating in cryogenic hydrogen initiated by a ≲300 fs, 92 eV free electron laser x-ray burst. The rise of the x-ray scattering amplitude from a second x-ray pulse probes the transition from dense cryogenic molecular hydrogen to a nearly uncorrelated plasmalike structure, indicating an electron-ion equilibration time of ˜0.9 ps. The rise time agrees with radiation hydrodynamics simulations based on a conductivity model for partially ionized plasma that is validated by two-temperature density-functional theory.

  2. Molecular dynamics simulations of dense plasmas

    SciTech Connect

    Collins, L.A.; Kress, J.D.; Kwon, I.; Lynch, D.L.; Troullier, N.

    1993-12-31

    We have performed quantum molecular dynamics simulations of hot, dense plasmas of hydrogen over a range of temperatures(0.1-5eV) and densities(0.0625-5g/cc). We determine the forces quantum mechanically from density functional, extended Huckel, and tight binding techniques and move the nuclei according to the classical equations of motion. We determine pair-correlation functions, diffusion coefficients, and electrical conductivities. We find that many-body effects predominate in this regime. We begin to obtain agreement with the OCP and Thomas-Fermi models only at the higher temperatures and densities.

  3. Electric and thermal resistivities in dense high-Z plasmas

    NASA Astrophysics Data System (ADS)

    Kitamura, Hikaru; Ichimaru, Setsuo

    1995-06-01

    Analytic expressions for the electric and thermal resistivities in dense high-Z plasmas have been obtained. The expressions incorporate phase-shift calculations of high-Z ion-sphere-model cross sections as well as existing quantum-mechanical transport calculations for hydrogen plasmas, and are applicable to fluid plasmas with 1<=Z<=26 strong-coupling effects between electrons and ions are particularly clarified. It has been shown that the heat capacity for a dense plasma may have a considerable effect, modifying the rate of thermal conduction. The results are compared with other theoretical predictions for those plasma parameters appropriate to degenerate stars.

  4. Hydrogen recycle and isotope exchange from dense carbon films

    SciTech Connect

    Clausing, R.E.; Heatherly, L.

    1987-03-01

    Dense carbon films were prepared by deposition from hydrogen plasmas to which methane was added. The initial hydrogen recycle coefficient from the films ranges from more than two to less than one. The films contain large amounts of hydrogen (up to 50 at. %). They adjust themselves to provide recycling coefficients near unity. Isotope changeover times tend to be long. The reservoir of hydrogen instantly available to the plasma to maintain or stabilize the recycle coefficient and isotopic composition of the plasma is 10/sup 15/ cm/sup -2/ or greater depending on film preparation, temperature, and prior plasma exposure conditions. Simulator observations tend to support and improve the understanding of the observations in TEXTOR and JET; however, they also point out the need for control of film deposition and operating parameters to provide desirable and reproducible properties. The films and the hydrogen isotopes they contain can be removed easily by plasma processes. Since the hydrogen in these films is relatively immobile except in the zone reached by energetic particles, or at temperatures above 400/sup 0/C, dense carbon films may be useful in managing the tritium recovery from near-term fusion experiments.

  5. Laser plasma diagnostics of dense plasmas

    SciTech Connect

    Glendinning, S.G.; Amendt, P.; Budil, K.S.; Hammel, B.A.; Kalantar, D.H.; Key, M.H.; Landen, O.L.; Remington, B.A.; Desenne, D.E.

    1995-07-12

    The authors describe several experiments on Nova that use laser-produced plasmas to generate x-rays capable of backlighting dense, cold plasmas (p {approximately} 1--3 gm/cm{sup 3}, kT {approximately} 5--10 eV, and areal density {rho}{ell}{approximately} 0.01--0.05 g/cm{sup 2}). The x-rays used vary over a wide range of h{nu}, from 80 eV (X-ray laser) to 9 keV. This allows probing of plasmas relevant to many hydrodynamic experiments. Typical diagnostics are 100 ps pinhole framing cameras for a long pulse backlighter and a time-integrated CCD camera for a short pulse backlighter.

  6. Topological Surface States in Dense Solid Hydrogen.

    PubMed

    Naumov, Ivan I; Hemley, Russell J

    2016-11-11

    Metallization of dense hydrogen and associated possible high-temperature superconductivity represents one of the key problems of physics. Recent theoretical studies indicate that before becoming a good metal, compressed solid hydrogen passes through a semimetallic stage. We show that such semimetallic phases predicted to be the most stable at multimegabar (∼300  GPa) pressures are not conventional semimetals: they exhibit topological metallic surface states inside the bulk "direct" gap in the two-dimensional surface Brillouin zone; that is, metallic surfaces may appear even when the bulk of the material remains insulating. Examples include hydrogen in the Cmca-12 and Cmca-4 structures; Pbcn hydrogen also has metallic surface states but they are of a nontopological nature. The results provide predictions for future measurements, including probes of possible surface superconductivity in dense hydrogen.

  7. Topological Surface States in Dense Solid Hydrogen

    NASA Astrophysics Data System (ADS)

    Naumov, Ivan I.; Hemley, Russell J.

    2016-11-01

    Metallization of dense hydrogen and associated possible high-temperature superconductivity represents one of the key problems of physics. Recent theoretical studies indicate that before becoming a good metal, compressed solid hydrogen passes through a semimetallic stage. We show that such semimetallic phases predicted to be the most stable at multimegabar (˜300 GPa ) pressures are not conventional semimetals: they exhibit topological metallic surface states inside the bulk "direct" gap in the two-dimensional surface Brillouin zone; that is, metallic surfaces may appear even when the bulk of the material remains insulating. Examples include hydrogen in the Cmca-12 and Cmca-4 structures; Pbcn hydrogen also has metallic surface states but they are of a nontopological nature. The results provide predictions for future measurements, including probes of possible surface superconductivity in dense hydrogen.

  8. Liquidlike state of dense hydrogen

    NASA Technical Reports Server (NTRS)

    Carlsson, A. E.; Ashcroft, N. W.

    1984-01-01

    Some difficulties associated with estimates of the ground-state energy difference between liquid and solid metallic hydrogen based on many-body perturbation theory are pointed out. Arguments based on liquid-state perturbation theory which indicate that the energy difference may be much smaller than was found in a previous calculation are presented.

  9. Compton scattering measurements from dense plasmas

    DOE PAGES

    Glenzer, S. H.; Neumayer, P.; Doppner, T.; ...

    2008-06-12

    Here, Compton scattering techniques have been developed for accurate measurements of densities and temperatures in dense plasmas. One future challenge is the application of this technique to characterize compressed matter on the National Ignition Facility where hydrogen and beryllium will approach extremely dense states of matter of up to 1000 g/cc. In this regime, the density, compressibility, and capsule fuel adiabat may be directly measured from the Compton scattered spectrum of a high-energy x-ray line source. Specifically, the scattered spectra directly reflect the electron velocity distribution. In non-degenerate plasmas, the width provides an accurate measure of the electron temperatures, whilemore » in partially Fermi degenerate systems that occur in laser-compressed matter it provides the Fermi energy and hence the electron density. Both of these regimes have been accessed in experiments at the Omega laser by employing isochorically heated solid-density beryllium and moderately compressed beryllium foil targets. In the latter experiment, compressions by a factor of 3 at pressures of 40 Mbar have been measured in excellent agreement with radiation hydrodynamic modeling.« less

  10. Renormalization plasma shielding effects on scattering entanglement fidelity in dense plasmas

    SciTech Connect

    Lee, Gyeong Won; Shim, Jaewon; Jung, Young-Dae

    2014-10-15

    The influence of renormalization plasma screening on the entanglement fidelity for the elastic electron-atom scattering is investigated in partially ionized dense hydrogen plasmas. The partial wave analysis and effective interaction potential are employed to obtain the scattering entanglement fidelity in dense hydrogen plasmas as functions of the collision energy, the Debye length, and the renormalization parameter. It is found that the renormalization plasma shielding enhances the scattering entanglement fidelity. Hence, we show that the transmission of the quantum information can be increased about 10% due to the renormalization shielding effect in dense hydrogen plasmas. It is also found that the renormalization shielding effect on the entanglement fidelity for the electron-atom collision increases with an increase of the collision energy. In addition, the renormalization shielding function increases with increasing collision energy and saturates to the unity with an increase of the Debye length.

  11. Equilibration dynamics and conductivity of warm dense hydrogen

    NASA Astrophysics Data System (ADS)

    Zastrau, U.; Sperling, P.; Becker, A.; Bornath, T.; Bredow, R.; Döppner, T.; Dziarzhytski, S.; Fennel, T.; Fletcher, L. B.; Förster, E.; Fortmann, C.; Glenzer, S. H.; Göde, S.; Gregori, G.; Harmand, M.; Hilbert, V.; Holst, B.; Laarmann, T.; Lee, H. J.; Ma, T.; Mithen, J. P.; Mitzner, R.; Murphy, C. D.; Nakatsutsumi, M.; Neumayer, P.; Przystawik, A.; Roling, S.; Schulz, M.; Siemer, B.; Skruszewicz, S.; Tiggesbäumker, J.; Toleikis, S.; Tschentscher, T.; White, T.; Wöstmann, M.; Zacharias, H.; Redmer, R.

    2014-07-01

    We investigate subpicosecond dynamics of warm dense hydrogen at the XUV free-electron laser facility (FLASH) at DESY (Hamburg). Ultrafast impulsive electron heating is initiated by a ≤300-fs short x-ray burst of 92-eV photon energy. A second pulse probes the sample via x-ray scattering at jitter-free variable time delay. We show that the initial molecular structure dissociates within (0.9±0.2) ps, allowing us to infer the energy transfer rate between electrons and ions. We evaluate Saha and Thomas-Fermi ionization models in radiation hydrodynamics simulations, predicting plasma parameters that are subsequently used to calculate the static structure factor. A conductivity model for partially ionized plasma is validated by two-temperature density-functional theory coupled to molecular dynamic simulations and agrees with the experimental data. Our results provide important insights and the needed experimental data on transport properties of dense plasmas.

  12. Quantum statistical mechanics of dense partially ionized hydrogen

    NASA Technical Reports Server (NTRS)

    Dewitt, H. E.; Rogers, F. J.

    1972-01-01

    The theory of dense hydrogen plasmas beginning with the two component quantum grand partition function is reviewed. It is shown that ionization equilibrium and molecular dissociation equilibrium can be treated in the same manner with proper consideration of all two-body states. A quantum perturbation expansion is used to give an accurate calculation of the equation of state of the gas for any degree of dissociation and ionization. The statistical mechanical calculation of the plasma equation of state is intended for stellar interiors. The general approach is extended to the calculation of the equation of state of the outer layers of large planets.

  13. Atomic phenomena in dense plasmas

    SciTech Connect

    Weisheit, J.C.

    1981-03-01

    The following chapters are included: (1) the plasma environment, (2) perturbations of atomic structure, (3) perturbations of atomic collisions, (4) formation of spectral lines, and (5) dielectronic recombination. (MOW)

  14. Filamentation in the pinched column of the dense plasma focus

    NASA Astrophysics Data System (ADS)

    Kubes, P.; Paduch, M.; Cikhardt, J.; Cikhardtova, B.; Klir, D.; Kravarik, J.; Rezac, K.; Zielinska, E.; Sadowski, M. J.; Szymaszek, A.; Tomaszewski, K.; Zaloga, D.

    2017-03-01

    The paper describes the filamentary structure observed in the high-energy ultraviolet radiation for discharges performed at the hydrogen- or deuterium-filling and at the puffing of hydrogen, deuterium or helium, in a mega-ampere dense plasma-focus facility. The lifetime of this structure overcomes 50 ns. These filaments connect the surface of a pinched column with internal plasmoids formed at different combinations of filling and puffing gases and they should transport some current and plasma. During all the investigated deuterium shots, the fusion-produced neutrons were recorded. Therefore, deuterons should be present in the region of their acceleration, independent of the applied puffing of the gas. Simultaneously with the observed filaments, inside the dense plasma column small plasma-balls of mm-dimensions were observed, which had a similar lifetime (longer than the relaxation time) and quasi-stationary positions in the discharge volume. The observed filaments and balls might be a manifestation of the (i) discrete spatial structure of the current flowing through and around the dense plasma column and (ii) transport of the plasma from external layers to the central region. Their formation and visualization were easier due to the application of air admixtures in the puffed gas.

  15. Nuclear quantum dynamics in dense hydrogen

    PubMed Central

    Kang, Dongdong; Sun, Huayang; Dai, Jiayu; Chen, Wenbo; Zhao, Zengxiu; Hou, Yong; Zeng, Jiaolong; Yuan, Jianmin

    2014-01-01

    Nuclear dynamics in dense hydrogen, which is determined by the key physics of large-angle scattering or many-body collisions between particles, is crucial for the dynamics of planet's evolution and hydrodynamical processes in inertial confinement confusion. Here, using improved ab initio path-integral molecular dynamics simulations, we investigated the nuclear quantum dynamics regarding transport behaviors of dense hydrogen up to the temperatures of 1 eV. With the inclusion of nuclear quantum effects (NQEs), the ionic diffusions are largely higher than the classical treatment by the magnitude from 20% to 146% as the temperature is decreased from 1 eV to 0.3 eV at 10 g/cm3, meanwhile, electrical and thermal conductivities are significantly lowered. In particular, the ionic diffusion is found much larger than that without NQEs even when both the ionic distributions are the same at 1 eV. The significant quantum delocalization of ions introduces remarkably different scattering cross section between protons compared with classical particle treatments, which explains the large difference of transport properties induced by NQEs. The Stokes-Einstein relation, Wiedemann-Franz law, and isotope effects are re-examined, showing different behaviors in nuclear quantum dynamics. PMID:24968754

  16. A dense plasma ultraviolet source

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Mcfarland, D. R.

    1978-01-01

    The intense ultraviolet emission from the NASA Hypocycloidal-Pinch (HCP) plasma is investigated. The HCP consists of three disk electrodes whose cross section has a configuration similar to the cross section of a Mather-type plasma focus. Plasma foci were produced in deuterium, helium, xenon, and krypton gases in order to compare their emission characteristics. Time-integrated spectra in the wavelength range from 200 nm to 350 nm and temporal variations of the uv emission were obtained with a uv spectrometer and a photomultiplier system. Modifications to enhance uv emission in the iodine-laser pump band (250 to 290 nm) and preliminary results produced by these modifications are presented. Finally, the advantages of the HCP as a uv over use of conventional xenon lamps with respect to power output limit, spectral range, and lifetime are discussed.

  17. 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.

  18. Nuclear Probing of Dense Plasmas

    SciTech Connect

    Richard Petrasso

    2007-02-14

    The object of inertial confinement fusion (ICF) is to compress a fuel capsule to a state with high enough density and temperature to ignite, starting a self-sustaining fusion burn that consumes much of the fuel and releases a large amount of energy. The national ICF research program is trying to reach this goal, especially through experiments at the OMEGA laser facility of the University of Rochester Laboratory of Laser Energetics (LLE), planned experiments at the National Ignition Facility (NIF) under construction at the Lawrence Livermore National Laboratory (LLNL), and experimental and theoretical work at other national laboratories. The work by MIT reported here has played several important roles in this national program. First, the development of new and improved charged-particle-based plasma diagnostics has allowed the gathering of new and unique diagnostic information about the implosions of fuel capsules in ICF experiments, providing new means for evaluating experiments and for studying capsule implosion dynamics. Proton spectrometers have become the standard for evaluating the mass assembly in compressed capsules in experiments at OMEGA; the measured energy downshift of either primary or secondary D3He fusion protons to determines the areal density, or ?R, of imploded capsules. The Proton Temporal Diagnostic measures the time history of fusion burn, and multiple proton emission imaging cameras reveal the 3-D spatial distribution of fusion burn. A new compact neutron spectrometer, for measuring fusion yield, is described here for the first time. And of especially high importance to future work is the Magnetic Recoil Spectrometer (MRS), which is a neutron spectrometer that will be used to study a range of important performance parameters in future experiments at the NIF. A prototype is currently being prepared for testing at OMEGA, using a magnet funded by this grant. Second, MIT has used these diagnostic instruments to perform its own physics experiments

  19. Quantum statistical mechanics of dense partially ionized hydrogen.

    NASA Technical Reports Server (NTRS)

    Dewitt, H. E.; Rogers, F. J.

    1972-01-01

    The theory of dense hydrogenic plasmas beginning with the two component quantum grand partition function is reviewed. It is shown that ionization equilibrium and molecular dissociation equilibrium can be treated in the same manner with proper consideration of all two-body states. A quantum perturbation expansion is used to give an accurate calculation of the equation of state of the gas for any degree of dissociation and ionization. In this theory, the effective interaction between any two charges is the dynamic screened potential obtained from the plasma dielectric function. We make the static approximation; and we carry out detailed numerical calculations with the bound and scattering states of the Debye potential, using the Beth-Uhlenbeck form of the quantum second virial coefficient. We compare our results with calculations from the Saha equation.

  20. Order in dense hydrogen at low temperatures

    PubMed Central

    Edwards, B.; Ashcroft, N. W.

    2004-01-01

    By increase in density, impelled by pressure, the electronic energy bands in dense hydrogen attain significant widths. Nevertheless, arguments can be advanced suggesting that a physically consistent description of the general consequences of this electronic structure can still be constructed from interacting but state-dependent multipoles. These reflect, in fact self-consistently, a disorder-induced localization of electron states partially manifesting the effects of proton dynamics; they retain very considerable spatial inhomogeneity (as they certainly do in the molecular limit). This description, which is valid provided that an overall energy gap has not closed, leads at a mean-field level to the expected quadrupolar coupling, but also for certain structures to the eventual emergence of dipolar terms and their coupling when a state of broken charge symmetry is developed. A simple Hamiltonian incorporating these basic features then leads to a high-density, low-temperature phase diagram that appears to be in substantial agreement with experiment. In particular, it accounts for the fact that whereas the phase I–II phase boundary has a significant isotope dependence, the phase II–III boundary has very little. PMID:15028839

  1. Electrical and thermal conductivities in dense plasmas

    SciTech Connect

    Faussurier, G. Blancard, C.; Combis, P.; Videau, L.

    2014-09-15

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  2. Dense, layered membranes for hydrogen separation

    DOEpatents

    Roark, Shane E.; MacKay, Richard; Mundschau, Michael V.

    2006-02-21

    This invention provides hydrogen-permeable membranes for separation of hydrogen from hydrogen-containing gases. The membranes are multi-layer having a central hydrogen-permeable layer with one or more catalyst layers, barrier layers, and/or protective layers. The invention also relates to membrane reactors employing the hydrogen-permeable membranes of the invention and to methods for separation of hydrogen from a hydrogen-containing gas using the membranes and reactors. The reactors of this invention can be combined with additional reactor systems for direct use of the separated hydrogen.

  3. X-ray scattering from dense plasmas

    NASA Astrophysics Data System (ADS)

    McSherry, Declan Joseph

    Dense plasmas were studied by probing them with kilovolt x-rays and measuring those scattered at various angles. The laser produced x-ray source emitted Ti He alpha 4.75 keV x-rays. Two different plasma types were explored. The first was created by laser driven shocks on either side of a sample foil consisting of 2 micron thickness of Al, sandwiched between two 1 micron CH layers. We have observed a peak in the x-ray scattering cross section, indicating diffraction from the plasma. However, the experimentally inferred plasma density, did not always agree broadly with the hydrodynamic simulation MEDX (A modified version of MEDUSA). The second plasma type that we studied was created by soft x-ray heating on either side of a sample foil, this time consisting of 1 micron thickness of Al, sandwiched between two 0.2 micron CH layers. Two foil targets, each consisting of a 0.1 micron thick Au foil mounted on 1 micron of CH, were placed 4 mm from the sample foil. The soft x-rays were produced by laser irradiating these two foil targets. We found that, 0.5 ns after the peak of the laser heating pulses, that the measured cross sections more closely matched those simulated using the Thomas Fermi model than the Inferno model. Later in time, at 2 ns, the plasma is approaching a weakly coupled state. This is the first time x-ray scattering cross sections have been measured from dense plasmas generated by radiatively heating both sides of the sample. Moreover, these are absolute values typically within a factor of two of expectation for early x-ray probe times.

  4. Nonlinear extraordinary wave in dense plasma

    SciTech Connect

    Krasovitskiy, V. B.; Turikov, V. A.

    2013-10-15

    Conditions for the propagation of a slow extraordinary wave in dense magnetized plasma are found. A solution to the set of relativistic hydrodynamic equations and Maxwell’s equations under the plasma resonance conditions, when the phase velocity of the nonlinear wave is equal to the speed of light, is obtained. The deviation of the wave frequency from the resonance frequency is accompanied by nonlinear longitudinal-transverse oscillations. It is shown that, in this case, the solution to the set of self-consistent equations obtained by averaging the initial equations over the period of high-frequency oscillations has the form of an envelope soliton. The possibility of excitation of a nonlinear wave in plasma by an external electromagnetic pulse is confirmed by numerical simulations.

  5. Monte Carlo simulations of ionization potential depression in dense plasmas

    SciTech Connect

    Stransky, M.

    2016-01-15

    A particle-particle grand canonical Monte Carlo model with Coulomb pair potential interaction was used to simulate modification of ionization potentials by electrostatic microfields. The Barnes-Hut tree algorithm [J. Barnes and P. Hut, Nature 324, 446 (1986)] was used to speed up calculations of electric potential. Atomic levels were approximated to be independent of the microfields as was assumed in the original paper by Ecker and Kröll [Phys. Fluids 6, 62 (1963)]; however, the available levels were limited by the corresponding mean inter-particle distance. The code was tested on hydrogen and dense aluminum plasmas. The amount of depression was up to 50% higher in the Debye-Hückel regime for hydrogen plasmas, in the high density limit, reasonable agreement was found with the Ecker-Kröll model for hydrogen plasmas and with the Stewart-Pyatt model [J. Stewart and K. Pyatt, Jr., Astrophys. J. 144, 1203 (1966)] for aluminum plasmas. Our 3D code is an improvement over the spherically symmetric simplifications of the Ecker-Kröll and Stewart-Pyatt models and is also not limited to high atomic numbers as is the underlying Thomas-Fermi model used in the Stewart-Pyatt model.

  6. Monte Carlo simulations of ionization potential depression in dense plasmas

    NASA Astrophysics Data System (ADS)

    Stransky, M.

    2016-01-01

    A particle-particle grand canonical Monte Carlo model with Coulomb pair potential interaction was used to simulate modification of ionization potentials by electrostatic microfields. The Barnes-Hut tree algorithm [J. Barnes and P. Hut, Nature 324, 446 (1986)] was used to speed up calculations of electric potential. Atomic levels were approximated to be independent of the microfields as was assumed in the original paper by Ecker and Kröll [Phys. Fluids 6, 62 (1963)]; however, the available levels were limited by the corresponding mean inter-particle distance. The code was tested on hydrogen and dense aluminum plasmas. The amount of depression was up to 50% higher in the Debye-Hückel regime for hydrogen plasmas, in the high density limit, reasonable agreement was found with the Ecker-Kröll model for hydrogen plasmas and with the Stewart-Pyatt model [J. Stewart and K. Pyatt, Jr., Astrophys. J. 144, 1203 (1966)] for aluminum plasmas. Our 3D code is an improvement over the spherically symmetric simplifications of the Ecker-Kröll and Stewart-Pyatt models and is also not limited to high atomic numbers as is the underlying Thomas-Fermi model used in the Stewart-Pyatt model.

  7. Megajoule Dense Plasma Focus Solid Target Experiments

    NASA Astrophysics Data System (ADS)

    Podpaly, Y. A.; Falabella, S.; Link, A.; Povilus, A.; Higginson, D. P.; Shaw, B. H.; Cooper, C. M.; Chapman, S.; Bennett, N.; Sipe, N.; Olson, R.; Schmidt, A. E.

    2016-10-01

    Dense plasma focus (DPF) devices are plasma sources that can produce significant neutron yields from beam into gas interactions. Yield increases, up to approximately a factor of five, have been observed previously on DPFs using solid targets, such as CD2 and D2O ice. In this work, we report on deuterium solid-target experiments at the Gemini DPF. A rotatable target holder and baffle arrangement were installed in the Gemini device which allowed four targets to be deployed sequentially without breaking vacuum. Solid targets of titanium deuteride were installed and systematically studied at a variety of fill pressures, bias voltages, and target positions. Target holder design, experimental results, and comparison to simulations will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  8. Nonplanar electrostatic shock waves in dense plasmas

    SciTech Connect

    Masood, W.; Rizvi, H.

    2010-02-15

    Two-dimensional quantum ion acoustic shock waves (QIASWs) are studied in an unmagnetized plasma consisting of electrons and ions. In this regard, a nonplanar quantum Kadomtsev-Petviashvili-Burgers (QKPB) equation is derived using the small amplitude perturbation expansion method. Using the tangent hyperbolic method, an analytical solution of the planar QKPB equation is obtained and subsequently used as the initial profile to numerically solve the nonplanar QKPB equation. It is observed that the increasing number density (and correspondingly the quantum Bohm potential) and kinematic viscosity affect the propagation characteristics of the QIASW. The temporal evolution of the nonplanar QIASW is investigated both in Cartesian and polar planes and the results are discussed from the numerical stand point. The results of the present study may be applicable in the study of propagation of small amplitude localized electrostatic shock structures in dense astrophysical environments.

  9. 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

  10. Nonlinear electrostatic excitations in magnetized dense plasmas with nonrelativistic and ultra-relativistic degenerate electrons

    SciTech Connect

    Mahmood, S.; Sadiq, Safeer; Haque, Q.

    2013-12-15

    Linear and nonlinear electrostatic waves in magnetized dense electron-ion plasmas are studied with nonrelativistic and ultra-relativistic degenerate and singly, doubly charged helium (He{sup +}, He{sup ++}) and hydrogen (H{sup +}) ions, respectively. The dispersion relation of electrostatic waves in magnetized dense plasmas is obtained under both the energy limits of degenerate electrons. Using reductive perturbation method, the Zakharov-Kuznetsov equation for nonlinear propagation of electrostatic solitons in magnetized dense plasmas is derived for both nonrelativistic and ultra-relativistic degenerate electrons. It is found that variations in plasma density, magnetic field intensity, different mass, and charge number of ions play significant role in the formation of electrostatic solitons in magnetized dense plasmas. The numerical plots are also presented for illustration using the parameters of dense astrophysical plasma situations such as white dwarfs and neutron stars exist in the literature. The present investigation is important for understanding the electrostatic waves propagation in the outer periphery of compact stars which mostly consists of hydrogen and helium ions with degenerate electrons in dense magnetized plasmas.

  11. Kinetic Simulations of Dense Plasma Focus Breakdown

    NASA Astrophysics Data System (ADS)

    Schmidt, A.; Higginson, D. P.; Jiang, S.; Link, A.; Povilus, A.; Sears, J.; Bennett, N.; Rose, D. V.; Welch, D. R.

    2015-11-01

    A dense plasma focus (DPF) device is a type of plasma gun that drives current through a set of coaxial electrodes to assemble gas inside the device and then implode that gas on axis to form a Z-pinch. This implosion drives hydrodynamic and kinetic instabilities that generate strong electric fields, which produces a short intense pulse of x-rays, high-energy (>100 keV) electrons and ions, and (in deuterium gas) neutrons. A strong factor in pinch performance is the initial breakdown and ionization of the gas along the insulator surface separating the two electrodes. The smoothness and isotropy of this ionized sheath are imprinted on the current sheath that travels along the electrodes, thus making it an important portion of the DPF to both understand and optimize. Here we use kinetic simulations in the Particle-in-cell code LSP to model the breakdown. Simulations are initiated with neutral gas and the breakdown modeled self-consistently as driven by a charged capacitor system. We also investigate novel geometries for the insulator and electrodes to attempt to control the electric field profile. The initial ionization fraction of gas is explored computationally to gauge possible advantages of pre-ionization which could be created experimentally via lasers or a glow-discharge. Prepared by LLNL under Contract DE-AC52-07NA27344.

  12. Direct numerical simulations of structure and transport in dense plasmas

    NASA Astrophysics Data System (ADS)

    Whitley, Heather; Castor, John; Murillo, Michael; Graziani, Frank; Cimarron Collaboration

    2011-10-01

    In recent years, high power laser facilities, such as NIF, and advanced diagnostics have enabled the determination of detailed properties of dense plasmas over unprecedented regimes. Understanding such plasmas, which may be partially degenerate and/or moderately coupled, represents a major challenge to the plasma physics community. We examine the accuracy and applicability of approximate effective potentials in the study of structural and dynamic properties of one and two component systems in the partially and fully ionized regimes. The diffractive Coulomb potential is derived from an exact quantum solution for a pair of particles while the fermionic character of the electrons is handled via an effective Pauli potential. We utilize classical hypernetted chain and molecular dynamics (MD) simulations to calculate static structure factors that can be compared to recent x-ray Thompson scattering experiments. We also examine whether these approximate potentials can be used to simulate electronic transport properties, such as thermal conductivity, and compare to recent quantum molecular dynamics calculations for hydrogen plasmas. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-490775.

  13. Optical Spectroscopy of a Mega-Ampere Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Dutra, Eric; Bennett, Nichelle; Hagen, Edward; Hunt, Eugene; Hsu, Scott; Koch, Jeffrey; Ross, Patrick; Waltman, Thomas

    2015-11-01

    An optical streaked spectroscopy system was developed to evaluate the spectral emission of the run-down, run-in and pinch phase on the Gemini Dense Plasma Focus (DPF). Time-resolved emission spectra were captured for hydrogen, deuterium, argon, and krypton gas from these phases. The emission was focused onto a fiber, and fed to a spectrometer that was coupled to a streak camera. Spectra of hydrogen, deuterium, argon, and krypton gas were modeled using Spec3D. Plasma parameters including electron density and temperature, from LSP simulations of the DPF discharge, were loaded into the Spec3D simulation to evaluate the emission spectra. Spectra collected from DPF on the streaked spectrometer system were then compared to the Spec3D simulations, and used to verify known optical emission lines for the various gases and to identify possible contaminants. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946, and by Los Alamos National Laboratory, under Contract no. DE-AC52-06NA25396 with the U.S. Department of Energy. DOE/NV/25946-2519.

  14. Ultrafast visualization of the structural evolution of dense hydrogen towards warm dense matter

    NASA Astrophysics Data System (ADS)

    Fletcher, Luke

    2016-10-01

    Hot dense hydrogen far from equilibrium is ubiquitous in nature occurring during some of the most violent and least understood events in our universe such as during star formation, supernova explosions, and the creation of cosmic rays. It is also a state of matter important for applications in inertial confinement fusion research and in laser particle acceleration. Rapid progress occurred in recent years characterizing the high-pressure structural properties of dense hydrogen under static or dynamic compression. Here, we show that spectrally and angularly resolved x-ray scattering measure the thermodynamic properties of dense hydrogen and resolve the ultrafast evolution and relaxation towards thermodynamic equilibrium. These studies apply ultra-bright x-ray pulses from the Linac Coherent Light (LCLS) source. The interaction of rapidly heated cryogenic hydrogen with a high-peak power optical laser is visualized with intense LCLS x-ray pulses in a high-repetition rate pump-probe setting. We demonstrate that electron-ion coupling is affected by the small number of particles in the Debye screening cloud resulting in much slower ion temperature equilibration than predicted by standard theory. This work was supported by the DOE Office of Science, Fusion Energy Science under FWP 100182.

  15. State densities and ionization equilibrium of atoms in dense plasmas

    NASA Astrophysics Data System (ADS)

    Shimamura, Isao; Fujimoto, Takashi

    1990-08-01

    The semiclassical Bohr-Sommerfeld quantization condition is used to derive an approximate analytical expression for the state density of the hydrogen atom in a dense plasma. An ion-sphere model with an infinitely high potential wall is assumed. The expression leads to a universal curve that spans all values of the electron density. The curve is continuous and smooth over the entire energy range, starting from the hydrogenic state density for low-lying bound states and approaching the plane-wave state density in the high-energy limit of the continuum. The number of bound states is approximately proportional to the inverse of the square root of the electron density. Integration of the state density over the Boltzmann distribution of the electronic energy results in an ionization equilibrium relation, leading to modified Saha's equation. The correction factor for this modified equation is a function of both the electron temperature and the electron density, and is expressed as a universal function of the ion coupling parameter.

  16. Dense plasma heating by crossing relativistic electron beams

    NASA Astrophysics Data System (ADS)

    Ratan, N.; Sircombe, N. J.; Ceurvorst, L.; Sadler, J.; Kasim, M. F.; Holloway, J.; Levy, M. C.; Trines, R.; Bingham, R.; Norreys, P. A.

    2017-01-01

    Here we investigate, using relativistic fluid theory and Vlasov-Maxwell simulations, the local heating of a dense plasma by two crossing electron beams. Heating occurs as an instability of the electron beams drives Langmuir waves, which couple nonlinearly into damped ion-acoustic waves. Simulations show a factor 2.8 increase in electron kinetic energy with a coupling efficiency of 18%. Our results support applications to the production of warm dense matter and as a driver for inertial fusion plasmas.

  17. Dense plasma heating by crossing relativistic electron beams.

    PubMed

    Ratan, N; Sircombe, N J; Ceurvorst, L; Sadler, J; Kasim, M F; Holloway, J; Levy, M C; Trines, R; Bingham, R; Norreys, P A

    2017-01-01

    Here we investigate, using relativistic fluid theory and Vlasov-Maxwell simulations, the local heating of a dense plasma by two crossing electron beams. Heating occurs as an instability of the electron beams drives Langmuir waves, which couple nonlinearly into damped ion-acoustic waves. Simulations show a factor 2.8 increase in electron kinetic energy with a coupling efficiency of 18%. Our results support applications to the production of warm dense matter and as a driver for inertial fusion plasmas.

  18. Dense Plasma Heating and Radiation Generation.

    DTIC Science & Technology

    1979-01-02

    34 Computor Investi- ations of Laser-Plasma Interactions", to be submitted to the 1979 IEEE International Conference on Plasma Science, Montreal, Canada...Identify by block number) carbon dioxide laser, beat heating, computor code, laser-plasma interactions. A pulsed power 20,ABSTRACT (Cntinue on reverse side

  19. Arbitrary electron acoustic waves in degenerate dense plasmas

    NASA Astrophysics Data System (ADS)

    Rahman, Ata-ur; Mushtaq, A.; Qamar, A.; Neelam, S.

    2016-12-01

    A theoretical investigation is carried out of the nonlinear dynamics of electron-acoustic waves in a collisionless and unmagnetized plasma whose constituents are non-degenerate cold electrons, ultra-relativistic degenerate electrons, and stationary ions. A dispersion relation is derived for linear EAWs. An energy integral equation involving the Sagdeev potential is derived, and basic properties of the large amplitude solitary structures are investigated in such a degenerate dense plasma. It is shown that only negative large amplitude EA solitary waves can exist in such a plasma system. The present analysis may be important to understand the collective interactions in degenerate dense plasmas, occurring in dense astrophysical environments as well as in laser-solid density plasma interaction experiments.

  20. Interaction of CO2 laser radiation with a dense Z-pinch plasma

    NASA Astrophysics Data System (ADS)

    Neufeld, C. R.

    1980-01-01

    Results obtained when a TEA-CO2 laser pulse is radially incident on a dense hydrogen Z-pinch plasma are presented. Perturbations of the plasma column are visible on high-speed streak photographs. Spectral measurements indicate that stimulated Brillouin scattering in the underdense plasma regions is the dominant mechanism for the observed backscattering of laser radiation by the plasma column. The time behavior of the backscattered signal can be very complex, both prompt and delayed backscatter having been observed under ostensibly identical experimental conditions. The backscattered power is typically 1-2 percent of the incident laser power.

  1. 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.

  2. Dynamical Crossover in Hot Dense Water: The Hydrogen Bond Role.

    PubMed

    Ranieri, Umbertoluca; Giura, Paola; Gorelli, Federico A; Santoro, Mario; Klotz, Stefan; Gillet, Philippe; Paolasini, Luigi; Koza, Michael Marek; Bove, Livia E

    2016-09-01

    We investigate the terahertz dynamics of liquid H2O as a function of pressure along the 450 K isotherm, by coupled quasielastic neutron scattering and inelastic X-ray scattering experiments. The pressure dependence of the single-molecule dynamics is anomalous in terms of both microscopic translation and rotation. In particular, the Stokes-Einstein-Debye equations are shown to be violated in hot water compressed to the GPa regime. The dynamics of the hydrogen bond network is only weakly affected by the pressure variation. The time scale of the structural relaxation driving the collective dynamics increases by a mere factor of 2 along the investigated isotherm, and the structural relaxation strength turns out to be almost pressure independent. Our results point at the persistence of the hydrogen bond network in hot dense water up to ice VII crystallization, thus questioning the long-standing perception that hydrogen bonds are broken in liquid water under the effect of compression.

  3. General trend for pressurized superconducting hydrogen-dense materials.

    PubMed

    Kim, Duck Young; Scheicher, Ralph H; Mao, Ho-kwang; Kang, Tae W; Ahuja, Rajeev

    2010-02-16

    The long-standing prediction that hydrogen can assume a metallic state under high pressure, combined with arguments put forward more recently that this state might even be superconducting up to high temperatures, continues to spur tremendous research activities toward the experimental realization of metallic hydrogen. These efforts have however so far been impeded by the enormous challenges associated with the exceedingly large required pressure. Hydrogen-dense materials, of the MH(4) form (where M can be, e.g., Si, Ge, or Sn) or of the MH(3) form (with M being, e.g., Al, Sc, Y, or La), allow for the rather exciting opportunity to carry out a proxy study of metallic hydrogen and associated high-temperature superconductivity at pressures within the reach of current techniques. At least one experimental report indicates that a superconducting state might have been observed already in SiH(4), and several theoretical studies have predicted superconductivity in pressurized hydrogen-rich materials; however, no systematic dependence on the applied pressure has yet been identified so far. In the present work, we have used first-principles methods in an attempt to predict the superconducting critical temperature (T(c)) as a function of pressure (P) for three metal-hydride systems of the MH(3) form, namely ScH(3), YH(3), and LaH(3). By comparing the obtained results, we are able to point out a general trend in the T(c)-dependence on P. These gained insights presented here are likely to stimulate further theoretical studies of metallic phases of hydrogen-dense materials and should lead to new experimental investigations of their superconducting properties.

  4. General trend for pressurized superconducting hydrogen-dense materials

    SciTech Connect

    Kim, Duck Young; Scheicher, Ralph H.; Mao, Ho-kwang; Kang, T. W.; Ahuja, Rajeev

    2010-02-16

    The long-standing prediction that hydrogen can assume a metallic state under high pressure, combined with arguments put forward more recently that this state might even be superconducting up to high temperatures, continues to spur tremendous research activities toward the experimental realization of metallic hydrogen. These efforts have however so far been impeded by the enormous challenges associated with the exceedingly large required pressure. Hydrogen-dense materials, of the MH{sub 4} form (where M can be, e.g., Si, Ge, or Sn) or of the MH{sub 3} form (with M being, e.g., Al, Sc, Y, or La), allow for the rather exciting opportunity to carry out a proxy study of metallic hydrogen and associated high-temperature superconductivity at pressures within the reach of current techniques. At least one experimental report indicates that a superconducting state might have been observed already in SiH{sub 4}, and several theoretical studies have predicted superconductivity in pressurized hydrogen-rich materials; however, no systematic dependence on the applied pressure has yet been identified so far. In the present work, we have used first-principles methods in an attempt to predict the superconducting critical temperature (T{sub c}) as a function of pressure (P) for three metal-hydride systems of the MH{sub 3} form, namely ScH{sub 3}, YH{sub 3}, and LaH{sub 3}. By comparing the obtained results, we are able to point out a general trend in the T{sub c}-dependence on P. These gained insights presented here are likely to stimulate further theoretical studies of metallic phases of hydrogen-dense materials and should lead to new experimental investigations of their superconducting properties.

  5. Gas-injection experiments on a dense plasma focus

    SciTech Connect

    Barnouin, O.; Javedani, J.; Del Medico, S.; Miley, G.H.; Bromley, B.

    1994-12-31

    Rockford Technology Associates, Inc. (RTA) has been doing experiments on the Dense Plasma focus (DPF) device at the Fusion Studies Laboratory of the University of Illinois. This DPF consists of four racks of five 2-{mu}F capacitors whose charge is switched onto the inner electrode of a plasma focus by four Trigatron spark gaps. The stored energy is 12.5 kJ at 25 kV. The bank is usually discharged in a static fill of H{sub 2} at {approx} 6 torr. Preliminary experiments aimed at exploring the potential of the DPF device as a magnetoplasmadynamic (MPD) thruster and as an x-ray source for lithography have investigated various alternative ways of injecting gas between the electrodes. One of those approaches consists of injecting gas from the tip of the inner electrode at a steady rate. In this operation, the DPF chamber pressure was held constant by running the vacuum pump at full throttle. This operation simulated simultaneous pulsed injection at the base insulator and electrode tip. Hydrogen was fed through a 1/16th-inch hole at a flow rate of {approx} 90 cm/s. Pulsing was then performed at 23 kV, and the corresponding variations of the current were observed using a Rogowski coil. It is found that the plasma collapses into a pinch at the same time as in conventional experiments using a static fill. The singularity in the current waveform is slightly smaller with tip injection, but its size and shape are easily reproducible. Further details and comparison of this operation with conventional pulsing will be presented.

  6. Hydrogen manufacturing using plasma reformers

    SciTech Connect

    Bromberg, L.; Cohn, D.R.; Rabinovich, A.; Hochgreb, S.; O`Brien, C.

    1996-10-01

    Manufacturing of hydrogen from hydrocarbon fuels is needed for a variety of applications. These applications include fuel cells used in stationary electric power production and in vehicular propulsion. Hydrogen can also be used for various combustion engine systems. There is a wide range of requirements on the capacity of the hydrogen manufacturing system, the purity of the hydrogen fuel, and capability for rapid response. The overall objectives of a hydrogen manufacturing facility are to operate with high availability at the lowest possible cost and to have minimal adverse environmental impact. Plasma technology has potential to significantly alleviate shortcomings of conventional means of manufacturing hydrogen. These shortcomings include cost and deterioration of catalysts; limitations on hydrogen production from heavy hydrocarbons; limitations on rapid response; and size and weight requirements. In addition, use of plasma technology could provide for a greater variety of operating modes; in particular the possibility of virtual elimination of CO{sub 2} production by pyrolytic operation. This mode of hydrogen production may be of increasing importance due to recent additional evidence of global warming.

  7. Transport coefficients for dense metal plasmas

    NASA Astrophysics Data System (ADS)

    Kuhlbrodt, Sandra; Redmer, Ronald

    2000-11-01

    Thermoelectric transport coefficients of metal plasmas are calculated within the linear response theory applied previously to determine the electrical conductivity of Al and Cu plasmas [R. Redmer, Phys. Rev. E 59, 1073 (1999)]. We consider temperatures of 1-3 eV and densities of 0.001-1 g/cm3 as relevant in rapid wire evaporation experiments. The plasma composition is calculated considering higher ionization stages of atoms up to 5+, and solving the respective system of coupled mass action laws. Interactions between charged particles are treated on T matrix level. Results for the electrical conductivity of various metal plasmas are in reasonable agreement with experimental data. Thermal conductivity and thermopower are also given. In addition, we compare with experimental data for temperatures up to 25 eV and liquidlike densities.

  8. Cluster model of aluminum dense vapor plasma

    NASA Astrophysics Data System (ADS)

    Khomkin, A. L.; Shumikhin, A. S.

    2009-08-01

    The chemical model of aluminum vapor plasma, that take into account the formation of neutral and charged clusters, is suggested. Caloric and thermal equations of state and composition of plasma were received using the available information about properties of metal clusters. It is shown, that aluminum vapors are clusterized with decrease of temperature and with increase of density. Pressure dependence on internal energy is calculated and comparison with experimental data is made. The important role of aluminum clusters, especially in an initial phase of the metals vapor heating, is demonstrated. It is shown, that the region of plasma clusterization in gaseous phase agree with known literature data for binodal of vapor-liquid transition from gaseous region. Suggested cluster model may be used to forecast the location of metal vapors binodal. The conductivity of aluminum vapor plasma was calculated. The satisfactory agreement with available experimental data is received.

  9. Hot-dense hydrogen study up to 300 GPa

    NASA Astrophysics Data System (ADS)

    Zha, Chang-Sheng

    Hydrogen study under extreme pressure-temperature conditions has fundamental importance for the development of condensed physics. The prediction of insulator to metallic state transition at sufficient high pressure has been a long-standing open question for the high pressure physics community. Recently, more experimental and theoretical interests were focused on the hot-dense state of hydrogen. A numerous investigations indicated a turnover melting line with a maximum point around ~100 GPa. First-principle theoretical models indicate that the metallization could be a liquid-liquid transition just above the melting line. Experiments for these studies were mostly conducted in shock compression or pulsed laser heating in static compression resulted in large controversy observations. Hydrogen study also has been one of the engines driving the advance of static pressure-temperature technologies. New developments in hydrogen study have brought static pressure generation and signal probing technique into 300 ~400 GPa range, leading to more new phases found. New experimental results using static pressure-temperature DAC techniques demonstrate that hydrogen has much more complicated phase behaviors at multiple megabar pressure range than that expected previously.

  10. Electronic excitations and metallization of dense solid hydrogen

    PubMed Central

    Cohen, R. E.; Naumov, Ivan I.; Hemley, Russell J.

    2013-01-01

    Theoretical calculations and an assessment of recent experimental results for dense solid hydrogen lead to a unique scenario for the metallization of hydrogen under pressure. The existence of layered structures based on graphene sheets gives rise to an electronic structure related to unique features found in graphene that are well studied in the carbon phase. The honeycombed layered structure for hydrogen at high density, first predicted in molecular calculations, produces a complex optical response. The metallization of hydrogen is very different from that originally proposed via a phase transition to a close-packed monoatomic structure, and different from simple metallization recently used to interpret recent experimental data. These different mechanisms for metallization have very different experimental signatures. We show that the shift of the main visible absorption edge does not constrain the point of band gap closure, in contrast with recent claims. This conclusion is confirmed by measured optical spectra, including spectra obtained to low photon energies in the infrared region for phases III and IV of hydrogen. PMID:23904476

  11. Laboratory measurements of the resistivity of warm dense plasmas

    NASA Astrophysics Data System (ADS)

    Booth, Nicola; Robinson, Alex; Hakel, Peter; Gregori, Ginaluca; Rajeev, Pattathil; Woolsey, Nigel

    2015-11-01

    In this talk we will present a method for studying material resistivity in warm dense plasmas in the laboratory in which we interrogate the microphysics of the low energy electron distributions associated with an anisotropic return current. Through experimental measurements of the polarization of the Ly- α doublet emission (2s1 / 2-2p1 / 2,3/2 transitions) of sulphur, we determine the resistivity of a sulphur-doped plastic target heated to warm dense conditions by an ultra-intense laser at relativistic intensities, I ~ 5 ×1020 Wcm-2. We describe a method of exploiting classical x-ray scattering to separately measure both the π- and σ- polarizations of Ly-α1 spectral emission in a single shot. These measurements make it possible to explore fundamental material properties such as resistivity in warm and hot dense plasmas through matching plasma physics modelling to atomic physics calculations of the experimentally measured large, positive, polarisation.

  12. Physics of High Temperature, Dense Plasmas.

    DTIC Science & Technology

    1984-01-01

    34Investigation of the High-Energy Acceleration Mode in the Coaxial Gun," Phys. Fluids, Suppl., S28, (1964). I. 9. Dattner, A. and Eninger J...34Studies of a Coaxial Plasma Gun," Phys. Fluids, Suppl., S41, (1964). II. 10. Wilcox, J. M., Pugh, E., Dattner, A. and Eninger , J., "Experimental Study of

  13. PIMC Validation of Effective Quantum Potentials for MD Simulations of Dense Plasmas

    NASA Astrophysics Data System (ADS)

    Whitley, Heather D.; Castor, John I.; Langdon, A. Bruce; Khairallah, Saad A.; Surh, Michael P.; Dubois, Jonathan L.; Alder, Berni J.; Draeger, Erik W.; Schwegler, Eric; Graziani, Frank R.; Murillo, Michael S.

    2010-11-01

    Molecular dynamics (MD) simulations of dense plasmas, such as those found in non-equilibrium laser fusion experiments, are challenging due to the importance of several quantum mechanical effects. We currently employ approximate statistical potentials, obtained exactly in the pair approximation from a numerical solution of the Bloch equation for the Coulomb density matrix. The fermionic character of the electrons is handled via an effective Pauli potential. We first study the accuracy of existing pair potentials and their extension to lower temperature and high Z ions by examining the exact pair density matrix. We then perform classical hypernetted chain and MD simulations using those effective potentials to study equilibrium thermodynamics of dense plasmas. Fully quantum path integral Monte Carlo (PIMC) simulations are used to gauge the accuracy of the classical calculations for dense hydrogen. Using feedback from the PIMC, we can further refine the effective Coulomb and Pauli potentials. Prepared by LLNL under Contract DE-AC52-07NA27344.

  14. Equation of state and transport coefficients for dense plasmas.

    PubMed

    Blancard, C; Faussurier, G

    2004-01-01

    We hereby present a model to describe the thermodynamic and transport properties of dense plasmas. The electronic and ionic structures are determined self-consistently using finite-temperature density functional theory and Gibbs-Bogolyubov inequality. The main thermodynamic quantities, i.e., internal energy, pressure, entropy, and sound speed, are obtained by numerical differentiation of the plasma total Helmholtz free energy. Electronic electrical and thermal conductivities are calculated from the Ziman approach. Ionic transport coefficients are estimated using those of hard-sphere system and the Rosenfeld semiempirical "universal" correspondence between excess entropy and dimensionless transport coefficients of dense fluids. Numerical results and comparisons with experiments are presented and discussed.

  15. Kinetic theory of the interdiffusion coefficient in dense plasmas

    SciTech Connect

    Boercker, D.B.

    1986-08-01

    Naive applications of Spitzer's theory to very dense plasmas can lead to negative diffusion coefficients. The interdiffusion coefficients in Binary Ionic Mixtures (two species of point ions in a uniform neutralizing background) have been calculated recently using molecular dynamics techniques. These calculations can provide useful benchmarks for theoretical evaluations of the diffusion coefficient in dense plasma mixtures. This paper gives a brief description of a kinetic theoretic approximation to the diffusion coefficient which generalizes Spitzer to high density and is in excellent agreement with the computer simulations. 15 refs., 1 fig., 2 tabs.

  16. Dense Plasma Heating and Radiation Generation.

    DTIC Science & Technology

    1980-05-30

    INSTRUCTIONS ~~~~~~ B OUET ~iNPGEFORE COMPLETING FORM I. RPORTmumsZ. GVT AC INNo.i S. ACCIPIENT’S CATALOG MUM694 ~~ 80-0981 F,6-~IS~ � 4. r r~ejandsw... p M. Kristiansen and M.O. Hagler AFOSR 74-2639 ~ 9. 9%RFOR4fpN ORGAMIZAT1om NAME ANO ADDRESS 10. PROGRAM ELEMEN T. DRO.IECT, TASK Plasma Laboratory...8217AA P ’t1JIMIS Dept. of Electrical Engineering 2301/A Texas Tech University, Lubbock, Texas 79409, 61102F 20Il It. CONTROLLING OFFICE MAMIE AND AOhESS

  17. Dense Plasma Characterization by X-Ray Thomson Scattering

    NASA Astrophysics Data System (ADS)

    Glenzer, Siegfried H.

    2001-10-01

    Solid-density plasmas close to the Fermi degenerate state are a fundamental state of matter that occurs in high energy density laboratory experiments. It has been a long-standing goal to study the microscopic properties of these dense plasmas because conventional diagnostic techniques and standard plasma theory that treat the interactions between particles as a small correction are not applicable. We have recently succeeded measuring the temperature of this previously unexplored regime of matter with a proof-of-principal experiment at the Omega laser facility at LLE, U. Rochester. We used spectrally-resolved 4.5-keV x-ray scattering from a solid-density beryllium plasma. The source is provided by a highly ionized resonance K-line from a Ti plasma. The sample is heated volumetrically by x-rays from another set of mid-Z plasmas produced by 10^15Wcm-2 laser beams. X-ray Thomson scattering provides for the first time detailed information on electron densities, temperature, and velocity distributions. In our experiments, we observe the Compton-downshifted spectral line that is broadened by the thermal motion of the electrons in the plasma indicating Te ≈ TF = 14 eV. The full range of dense plasmas, from Fermi degenerate, to strongly coupled, to high temperature ideal gas plasmas will now be accessible. For example, as the temperature is increased, the electron velocity distribution as measured by incoherent Thomson scattering will make a transition from a density-dependent parabolic Fermi distribution to the traditional Gaussian Boltzmann distribution. The technique has wide applications, ranging from studying the adiabat and compression of ICF fuels, to temperature measurements for radiatively heated foams. In addition, by accessing the collective scattering regime, basic dense plasma wave physics can be studied.

  18. PROTON-CONDUCTING DENSE CERAMIC MEMBRANES FOR HYDROGEN SEPARATION

    SciTech Connect

    Jerry Y.S. Lin

    2002-12-01

    This project is aimed at preparation of thin membranes of a modified strontium ceramic material on porous substrates with improved hydrogen permeance. The research work conducted in this reporting period was focused on studying synthesis methods for preparation of thin thulium doped strontium cerate (SrCe{sub 0.95}Tm{sub 0.05}O{sub 3}, SCTm) membranes. The following two methods were studied in the past year: (1) polymeric-gel casting and (2) dry-pressing. The polymeric-gel casting method includes preparation of mixed metal oxide gel and coating of the gel on a macroporous alumina support. Micrometer thick SCTm films of the perovskite structure can be obtained by this method. However, the deposited films are not hermetic and it may require about 50 coatings in order to obtain gas-tight SCTm films by this method. Asymmetric SCTm membranes consisting of a thick macroporous SCTm support and a thin SCTm layer can be effectively prepared by the dry-pressing method. The membranes were prepared by pressing together a thick layer of coarse SCTm powder and a thin layer of finer SCTm powder, followed by calcination and sintering under proper conditions. The asymmetric SCTm membranes have desired phase structure and are hermetic. Hydrogen permeation flux through the SCT membranes is inversely proportional to the thickness of the dense layer of the asymmetric membranes. The results show a substantial improvement in hydrogen permeation flux by reducing the SCTm membrane thickness.

  19. Elastic scattering of low energy electrons in partially ionized dense semiclassical plasma

    SciTech Connect

    Dzhumagulova, K. N. Shalenov, E. O.; Ramazanov, T. S.

    2015-08-15

    Elastic scattering of electrons by hydrogen atoms in a dense semiclassical hydrogen plasma for low impact energies has been studied. Differential scattering cross sections were calculated within the effective model of electron-atom interaction taking into account the effect of screening as well as the quantum mechanical effect of diffraction. The calculations were carried out on the basis of the phase-function method. The influence of the diffraction effect on the Ramsauer–Townsend effect was studied on the basis of a comparison with results made within the effective polarization model of the Buckingham type.

  20. Elastic scattering of low energy electrons in partially ionized dense semiclassical plasma

    NASA Astrophysics Data System (ADS)

    Dzhumagulova, K. N.; Shalenov, E. O.; Ramazanov, T. S.

    2015-08-01

    Elastic scattering of electrons by hydrogen atoms in a dense semiclassical hydrogen plasma for low impact energies has been studied. Differential scattering cross sections were calculated within the effective model of electron-atom interaction taking into account the effect of screening as well as the quantum mechanical effect of diffraction. The calculations were carried out on the basis of the phase-function method. The influence of the diffraction effect on the Ramsauer-Townsend effect was studied on the basis of a comparison with results made within the effective polarization model of the Buckingham type.

  1. Dense Metal Plasma in a Solenoid for Ion Beam Neutralization

    SciTech Connect

    Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.

    2010-10-30

    Space-charge neutralization is required to compress and focus a pulsed, high-current ion beam on a target for warm dense matter physics or heavy ion fusion experiments. We described approaches to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary space-charge compensating electrons. Among the options are plasma injection from pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means, by an array of movable Langmuir probes, by a small single probe, and by evaluating Stark broadening of the Balmer H beta spectral line. In the main approach described here, the plasma is produced at several cathode spots distributed azimuthally on the ring cathode. It is shown that the plasma is essentially hollow, as determined by the structure of the magnetic field, though the plasma density exceeds 1014 cm-3 in practically all zones of the solenoid volume if the ring electrode is placed a few centimeters off the center of the solenoid. The plasma is non-uniform and fluctuating, however, since its density exceeds the ion beam density it is believed that this approach could provide a practical solution to the space charge neutralization challenge.

  2. Accessibillity of Electron Bernstein Modes in Over-Dense Plasma

    SciTech Connect

    Batchelor, D.B.; Bigelow, T.S.; Carter, M.D.

    1999-04-12

    Mode-conversion between the ordinary, extraordinary and electron Bernstein modes near the plasma edge may allow signals generated by electrons in an over-dense plasma to be detected. Alternatively, high frequency power may gain accessibility to the core plasma through this mode conversion process. Many of the tools used for ion cyclotron antenna de-sign can also be applied near the electron cyclotron frequency. In this paper, we investigate the possibilities for an antenna that may couple to electron Bernstein modes inside an over-dense plasma. The optimum values for wavelengths that undergo mode-conversion are found by scanning the poloidal and toroidal response of the plasma using a warm plasma slab approximation with a sheared magnetic field. Only a very narrow region of the edge can be examined in this manner; however, ray tracing may be used to follow the mode converted power in a more general geometry. It is eventually hoped that the methods can be extended to a hot plasma representation. Using antenna design codes, some basic antenna shapes will be considered to see what types of antennas might be used to detect or launch modes that penetrate the cutoff layer in the edge plasma.

  3. Warm, Dense Plasma Characterization by X-ray Thomson Scattering

    SciTech Connect

    Landen, O L; Glenzer, S H; Cauble, R C; Lee, R W; Edwards, J E; Degroot, J S

    2000-07-18

    We describe how the powerful technique of spectrally resolved Thomson scattering can be extended to the x-ray regime, for direct measurements of the ionization state, density, temperature, and the microscopic behavior of dense cool plasmas. Such a direct measurement of microscopic parameters of solid density plasmas could eventually be used to properly interpret laboratory measurements of material properties such as thermal and electrical conductivity, EUS and opacity. In addition, x-ray Thomson scattering will provide new information on the characteristics of rarely and hitherto difficult to diagnose Fermi degenerate and strongly coupled plasmas.

  4. Ion structure in dense plasmas: MSA versus HNC

    NASA Astrophysics Data System (ADS)

    Wünsch, K.; Vorberger, J.; Gregori, G.; Gericke, D. O.

    2009-05-01

    We present results for the ionic structure in dense, moderately to strongly coupled plasmas using two models: the mean spherical approximation (MSA) and the hypernetted chain (HNC) approach. While the first method allows for an analytical solution, the latter has to be solved iteratively. Independent of the coupling strength, the results show only small differences when the ions are considered to form an unscreened one-component plasma (OCP) system. If the electrons are treated as a polarizable background, the different ways to incorporate the screening yield, however, large discrepancies between the models, particularly for more strongly coupled plasmas.

  5. Resistivity and anisotropic return currents in warm dense plasmas

    NASA Astrophysics Data System (ADS)

    Woolsey, Nigel; Booth, Nicola; Robinson, A.; Hakel, P.; Clarke, R.; Dance, R.; Doia, D.; Gizzi, L.; Gregori, G.; Koester, P.; Labate, L.; Li, B.; Makita, M.; Mancini, R.; Pasley, J.; Rajeev, P.; Riley, D.; Wagenaars, E.; Waugh, J.

    2015-11-01

    In an ultra-intense laser interaction with a solid, the electrons from the hot plasma are accelerated by the laser streaming into the solid behind, creating a dense plasma in the bulk. This provides a laboratory for creating warm dense matter in a parameter range where the material resistivity and equation of states are complex and mostly untested. Here we describe an experimental study of electron transport in a low atomic number (plastic) material at solid density and temperatures of 200 eV. The plastic is doped with sulphur as a diagnostic tracer to enable the observation of emission spectra. Through observing high positive polarisation in this emission it is possible to infer in situ anisotropic currents driving the heat transport. Matching the current anisotropy enables tests of resistivity models in these complex plasmas. Results show that the background resistivity at these conditions is high than expected from commonly used models.

  6. Magnetoacoustic solitons in dense astrophysical electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Mahmood, S.; Mushtaq, A.

    2013-08-01

    Nonlinear magnetoacoustic waves in dense electron-positron-ion plasmas are investigated by using three fluid quantum magnetohydrodynamic model. The quantum mechanical effects of electrons and positrons are taken into account due to their Fermionic nature (to obey Fermi statistics) and quantum diffraction effects (Bohm diffusion term) in the model. The reductive perturbation method is employed to derive the Korteweg-de Vries (KdV) equation for low amplitude magnetoacoustic soliton in dense electron-positron-ion plasmas. It is found that positron concentration has significant impact on the phase velocity of magnetoacoustic wave and on the formation of single pulse nonlinear structure. The numerical results are also illustrated by taking into account the plasma parameters of the outside layers of white dwarfs and neutron stars/pulsars.

  7. 1991 US-Japan workshop on Nuclear Fusion in Dense Plasmas

    SciTech Connect

    Ichimaru, S. . Dept. of Physics); Tajima, T. . Inst. for Fusion Studies)

    1991-10-01

    The scientific areas covered at the Workshop may be classified into the following subfields: (1) basic theory of dense plasma physics and its interface with atomic physics and nuclear physics; (2) physics of dense z-pinches, ICF plasmas etc; (3) stellar interior plasmas; (4) cold fusion; and (5) other dense plasmas.

  8. 1991 US-Japan workshop on Nuclear Fusion in Dense Plasmas. Proceedings

    SciTech Connect

    Ichimaru, S.; Tajima, T.

    1991-10-01

    The scientific areas covered at the Workshop may be classified into the following subfields: (1) basic theory of dense plasma physics and its interface with atomic physics and nuclear physics; (2) physics of dense z-pinches, ICF plasmas etc; (3) stellar interior plasmas; (4) cold fusion; and (5) other dense plasmas.

  9. Hugoniot measurements of double-shocked precompressed dense xenon plasmas.

    PubMed

    Zheng, J; Chen, Q F; Gu, Y J; Chen, Z Y

    2012-12-01

    The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ∼6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

  10. Soft X-Ray Thomson Scattering in Warm Dense Hydrogen at FLASH

    SciTech Connect

    Faustlin, R R; Toleikis, S; Bornath, T; Doppner, T; Dusterer, S; Forster, E; Fortmann, C; Glenzer, S H; Gode, S; Gregori, G; Irsig, R; Laarmann, T; Lee, H J; Li, B; Meiwes-Broer, K; Mithen, J; Przystawik, A; Redlin, H; Redmer, R; Reinholz, H; Ropke, G; Tavella, F; Thiele, R; Tiggesbaumker, J; Uschmann, I; Zastrau, U; Tschentscher, T

    2009-07-15

    We present collective Thomson scattering with soft x-ray free electron laser radiation as a method to track the evolution of warm dense matter plasmas with {approx}200 fs time resolution. In a pump-probe scheme an 800 nm laser heats a 20 {micro}m hydrogen droplet to the plasma state. After a variable time delay in the order of ps the plasma is probed by an x-ray ultra violet (XUV) pulse which scatters from the target and is recorded spectrally. Alternatively, in a self-Thomson scattering experiment, a single XUV pulse heats the target while a portion of its photons are being scattered probing the target. From such inelastic x-ray scattering spectra free electron temperature and density can be inferred giving insight on relaxation time scales in plasmas as well as the equation of state. We prove the feasibility of this method in the XUV range utilizing the free electron laser facility in Hamburg, FLASH. We recorded Thomson scattering spectra for hydrogen plasma, both in the self-scattering and in the pump-probe mode using optical laser heating.

  11. Equation of state of partially-ionized dense plasmas

    SciTech Connect

    Rogers, F.J.

    1989-09-28

    This paper describes methods for calculating the equation of state of partially-ionized dense plasmas. The term dense plasma is used rather than strongly coupled plasma, since it is possible that at plasma conditions such that only a few levels can be observed spectroscopically the plasma coupling parameters are not large. Due mainly to their importance in theoretical astrophysics, the properties of partially ionized plasmas have been of interest for a long while. More recently, this interest has intensified due to the development of methods for producing partially ionized plasmas in the laboratory. This has opened up large programs of experimental investigation and of practical application. In this paper we consider detailed statistical mechanical methods that explicitly treat the distribution over ionic species and their energy level structure. These detailed approaches are generally characterized as being in the chemical picture'' when a free energy expression is minimized or in the physical picture'' when the starting point is the grand canonical ensemble. 52 refs., 2 tabs.

  12. Diagnostics of Pulsed Hydrogen Plasmas

    NASA Astrophysics Data System (ADS)

    Dubois, Jerome; Cunge, Gilles; Joubert, Olivier; Darnon, Maxime; Vallier, Laurent; Posseme, Nicolas; Etching Group Team

    2014-10-01

    Hydrogen plasmas present a great potential interest for new materials such as graphene or C-nanotubes. To modify or clean such ultrathin layers without damaging the material, low ion energy bombardment is required (conditions such as those obtained in pulsed ICP reactor). By contrast, for other applications the ion energy must be high, to get a significant etch rate for example. To assist the development of innovative processes in H2 plasmas, we have thus analyzed systematically CW and pulsed H2 plasmas both with and without RF bias power. In particular, we carry out time-resolved ion flux, and time-averaged ion energy measurements in different pulsing configurations. A large variety of ion energies and shapes of IVDF are reported depending on pulsing parameters. The IVDF are typically very broad (due to the low ion transit time of low mass ion through the sheath) and either bi or tri-modal (H +, H2 + and H3 + contributions). The time variations of the ion flux in pulsed plasmas also presents peculiar features that will be discussed. Finally, we show that a specific issue is associated to H2 plasmas: they reduce the chamber walls material therefore releasing impurities (O atoms...) in the plasma with important consequences on processes.

  13. Dense plasma focus production in a hypocycloidal pinch

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Mcfarland, D. R.; Hohl, F.

    1975-01-01

    A type of high-power pinch apparatus consisting of disk electrodes was developed, and diagnostic measurements to study its mechanism of dense plasma production were made. The collapse fronts of the current sheets are well organized, and dense plasma focuses are produced on the axis with radial stability in excess of 5 microns. A plasma density greater than 10 to the 18th power/cubic cm was determined with Stark broadening and CO2 laser absorption. A plasma temperature of approximately 1 keV was measured with differential transmission of soft X-rays through thin foils. Essentially complete absorption of a high-energy CO2 laser beam was observed. The advantages of this apparatus over the coaxial plasma focus are in (1) the plasma volume, (2) the stability, (3) the containment time, (4) the easy access to additional heating by laser or electron beams, and (5) the possibility of scaling up to a multiple array for high-power operation.

  14. Influence of renormalization shielding on the electron-impact ionization process in dense partially ionized plasmas

    SciTech Connect

    Song, Mi-Young; Yoon, Jung-Sik; Jung, Young-Dae

    2015-04-15

    The renormalization shielding effects on the electron-impact ionization of hydrogen atom are investigated in dense partially ionized plasmas. The effective projectile-target interaction Hamiltonian and the semiclassical trajectory method are employed to obtain the transition amplitude as well as the ionization probability as functions of the impact parameter, the collision energy, and the renormalization parameter. It is found that the renormalization shielding effect suppresses the transition amplitude for the electron-impact ionization process in dense partially ionized plasmas. It is also found that the renormalization effect suppresses the differential ionization cross section in the peak impact parameter region. In addition, it is found that the influence of renormalization shielding on the ionization cross section decreases with an increase of the relative collision energy. The variations of the renormalization shielding effects on the electron-impact ionization cross section are also discussed.

  15. 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.

  16. Ponderomotive potential and backward Raman scattering in dense quantum plasmas

    SciTech Connect

    Son, S.

    2014-03-15

    The backward Raman scattering is studied in dense quantum plasmas. The coefficients in the backward Raman scattering is found to be underestimated (overestimated) in the classical theory if the excited Langmuir wave has low-wave vector (high-wave vector). The second-order quantum perturbation theory shows that the second harmonic of the ponderomotive potential arises naturally even in a single particle motion contrary to the classical prediction.

  17. Interaction of fast magnetoacoustic solitons in dense plasmas

    SciTech Connect

    Jahangir, R.; Saleem, Khalid; Masood, W.; Siddiq, M.; Batool, Nazia

    2015-09-15

    One dimensional propagation of fast magnetoacoustic solitary waves in dense plasmas with degenerate electrons is investigated in this paper in the small amplitude limit. In this regard, Korteweg deVries equation is derived and discussed using the plasma parameters that are typically found in white dwarf stars. The interaction of fast magnetoacoustic solitons is explored by using the Hirota bilinear formalism, which admits multi soliton solutions. It is observed that the values of the propagation vectors determine the interaction of solitary waves. It is further noted that the amplitude of the respective solitary waves remain unchanged after the interaction; however, they do experience a phase shift.

  18. Interaction of electromagnetic wave with quantum over dense plasma layer

    NASA Astrophysics Data System (ADS)

    Rajaei, Leila

    2016-10-01

    The anomalous transmission of electromagnetic wave in the cold over dense plasma is investigated using the quantum hydrodynamic approach. The quantum effect on the dispersion relation of the surface wave excited by the electromagnetic radiation is evaluated and compared with the classical regimes. It is shown that the quantum dispersion curve, in comparison with its classical behavior, has an asymptotic approach at larger wave numbers. Investigating the transmission conditions, the effects of the main different parameters of the model such as the plasma density and Fermi velocity on the rate of transmission are scrutinized.

  19. Ionic Transport Coefficients of Dense Plasmas without Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Daligault, J.; Baalrud, S. D.; Starrett, C. E.; Saumon, D.; Sjostrom, T.

    2016-10-01

    We present a theoretical model that allows a fast and accurate evaluation of ionic transport properties of realistic plasmas spanning from warm and dense to hot and dilute conditions, including mixtures. This is achieved by combining a recent kinetic theory based on effective interaction potentials with a model for the equilibrium radial density distribution based on an average atom model and the integral equations theory of fluids. The model should find broad use in applications where nonideal plasma conditions are traversed, including inertial confinement fusion, compact astrophysical objects, solar and extrasolar planets, and numerous present-day high energy density laboratory experiments.

  20. Pseudo-Potentials in Dense and He-like Hot temperature Plasmas

    NASA Astrophysics Data System (ADS)

    Deutsch, Claude; Rahal, Hamid

    2012-10-01

    Extending our former derivations in dense and high temperature plasmas of hydrogenic effective interactions mimiking the Heisenberg uncertainty principle [1,2], we worked out in a canonical ensemble, effective interactions in He-like plasmas where an orbital 1s electron remains strongly tighted to the He-like ions. The plasma electrons are then taken into account through appropriate Slater sums obtained in the most economical hydrogenic extension of the He-like bound and scattered states with angular orbital momentum l<3. Ground states are described by a multi-parametric HF approximation [3]. We thus obtain Diffraction-corrected electron-ion pseudo-potentials taking into account of a polarizable and nonpointlike ion core. Very large enhancements and discrepancies are obtained when they are contrasted to their H-like homologs with ion charge Z=2,10 and 92. These results are of obvious significance for He-like warm dense matter plasmas.Ionization is also considered.[4pt] [1] C. Deutsch, Phys. Lett. A60, 317 (1977)[4pt] [2] C. Deutsch, Y. Furutani and M.M. Gombert, Phys. Rep. 69,86 (1981)[0pt] [3] E. Clementi and C. Roetti, Atomic Data and Nucl. Data Tables, 14,177(1974)

  1. Predicted reentrant melting of dense hydrogen at ultra-high pressures

    PubMed Central

    Geng, Hua Y.; Wu, Q.

    2016-01-01

    The phase diagram of hydrogen is one of the most important challenges in high-pressure physics and astrophysics. Especially, the melting of dense hydrogen is complicated by dimer dissociation, metallization and nuclear quantum effect of protons, which together lead to a cold melting of dense hydrogen when above 500 GPa. Nonetheless, the variation of the melting curve at higher pressures is virtually uncharted. Here we report that using ab initio molecular dynamics and path integral simulations based on density functional theory, a new atomic phase is discovered, which gives an uplifting melting curve of dense hydrogen when beyond 2 TPa, and results in a reentrant solid-liquid transition before entering the Wigner crystalline phase of protons. The findings greatly extend the phase diagram of dense hydrogen, and put metallic hydrogen into the group of alkali metals, with its melting curve closely resembling those of lithium and sodium. PMID:27834405

  2. Dust-Coulomb waves in dense dusty plasmas

    NASA Astrophysics Data System (ADS)

    Rao, N. N.

    1999-12-01

    Dusty plasmas can be considered as tenuous, dilute or dense when the dust fugacity parameter f≡4πnd0λD2R˜NDR/λD satisfies f≪1, ˜1, or ≫1, where nd0, λD and R denote, respectively, the dust number density, the plasma Debye length and the dust grain size (radius), and ND=nd0λD3 is the dust plasma parameter. Dense dusty plasmas are shown to support a new kind of ultra low-frequency electrostatic dust mode which may be called the "Dust-Coulomb Wave" (DCW). In contrast to the dust-acoustic wave (DAW) and the dust-lattice wave (DLW) which exist even for constant grain charge, DCWs are accompanied by dust charge as well as number density perturbations which are proportional to each other. For frequencies much smaller than the grain charging frequency, DCWs propagate as normal modes with the phase speed CDC≡qd0/√mdR , where qd0 (md) is the charge (mass) of the dust grains. In the long wavelength limit, the DCW phase speed is much smaller than that of DAW (CDA), and scales as ˜CDA/√f . Thus, for a given wave number, the frequency regime for the existence of DCW is much lower than the DAW regime. A comparison between the three types of dust-modes (DCWs, DAWs, and DLWs) has been carried out.

  3. Visible light emission measurements from a dense electrothermal launcher plasma

    NASA Astrophysics Data System (ADS)

    Hankins, O. E.; Bourham, M. A.; Earnhart, J.; Gilligan, J. G.

    1993-01-01

    Measurements of the visible light emission from dense, weakly non-ideal plasmas have been performed on the experimental electrothermal launcher device 'SIRENS'. The plasma is created by the ablation or a Lexan insulator in the source, which then flows through a cylindrical barrel which serves as the material sample. Visible light emission spectra have been observed both in-bore and from the muzzle flash or the barrel, and from the flash or the source. Due to high plasma opacity (the plasma emits as a near blackbody) and absorption by the molecular components of the vapor shield, the hotter core or the arc has been difficult to observe. Recent measurements along the axis or the device indicate time-averaged plasma temperatures in the barrel or about 1 eV for lower energy shots, which agree with experimental measurements of the average heat flux and plasma conductivity along the barrel. Measurements or visible emission from the source indicate time averaged temperatures of 1 to 2 eV which agree with the theoretical estimates derived from ablated mass measurements and calculated estimates derived from plasma conductivity measurements.

  4. Electric field enhanced conductivity in strongly coupled dense metal plasma

    SciTech Connect

    Stephens, J.; Neuber, A.

    2012-06-15

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field ({approx}6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  5. Electric field enhanced conductivity in strongly coupled dense metal plasma

    NASA Astrophysics Data System (ADS)

    Stephens, J.; Neuber, A.

    2012-06-01

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field (˜6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  6. Insight into hydrogenation of graphene: Effect of hydrogen plasma chemistry

    SciTech Connect

    Felten, A.; Nittler, L.; Pireaux, J.-J.; McManus, D.; Rice, C.; Casiraghi, C.

    2014-11-03

    Plasma hydrogenation of graphene has been proposed as a tool to modify the properties of graphene. However, hydrogen plasma is a complex system and controlled hydrogenation of graphene suffers from a lack of understanding of the plasma chemistry. Here, we correlate the modifications induced on monolayer graphene studied by Raman spectroscopy with the hydrogen ions energy distributions obtained by mass spectrometry. We measure the energy distribution of H{sup +}, H{sub 2}{sup +}, and H{sub 3}{sup +} ions for different plasma conditions showing that their energy strongly depends on the sample position, pressure, and plasma power and can reach values as high as 45 eV. Based on these measurements, we speculate that under specific plasma parameters, protons should possess enough energy to penetrate the graphene sheet. Therefore, a graphene membrane could become, under certain conditions, transparent to both protons and electrons.

  7. Dense Plasma X-ray Scattering: Methods and Applications

    SciTech Connect

    Glenzer, S H; Lee, H J; Davis, P; Doppner, T; Falcone, R W; Fortmann, C; Hammel, B A; Kritcher, A L; Landen, O L; Lee, R W; Munro, D H; Redmer, R; Weber, S

    2009-08-19

    We have developed accurate x-ray scattering techniques to measure the physical properties of dense plasmas. Temperature and density are inferred from inelastic x-ray scattering data whose interpretation is model-independent for low to moderately coupled systems. Specifically, the spectral shape of the non-collective Compton scattering spectrum directly reflects the electron velocity distribution. In partially Fermi degenerate systems that have been investigated experimentally in laser shock-compressed beryllium, the Compton scattering spectrum provides the Fermi energy and hence the electron density. We show that forward scattering spectra that observe collective plasmon oscillations yield densities in agreement with Compton scattering. In addition, electron temperatures inferred from the dispersion of the plasmon feature are consistent with the ion temperature sensitive elastic scattering feature. Hence, theoretical models of the static ion-ion structure factor and consequently the equation of state of dense matter can be directly tested.

  8. Thermodynamic properties of hydrogen-helium plasmas

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1971-01-01

    The thermodynamic properties of an atomic hydrogen-helium plasma are calculated and tabulated for temperatures from 10,000 to 100,000 K as a function of the mass fraction ratio of atomic hydrogen. The tabulation is for densities from 10 to the minus 10th power to 10 to the minus 6th power gm/cu cm and for hydrogen mass fraction ratios of 0, 0.333, 0.600, 0.800, and 1.0, which correspond to pure helium, 50 percent hydrogen per unit volume, 75 percent hydrogen per unit volume, 89 percent hydrogen per unit volume, and pure hydrogen plasmas, respectively. From an appended computer program, calculations can be made at other densities and mass fractions. The program output agrees well with previous thermodynamic property calculations for limiting cases of pure hydrogen and pure helium plasmas.

  9. ICTP-IAEA Workshop on Dense Magnetized Plasma and Plasma Diagnostics: an executive summary

    NASA Astrophysics Data System (ADS)

    Gribkov, V. A.; Mank, G.; Markowicz, A.; Miklaszewski, R.; Tuniz, C.; Crespo, M. L.

    2011-12-01

    The Workshop on Dense Magnetized Plasma and Plasma Diagnostics was held from 15 to 26 November 2010 at the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy. It was attended by 60 participants, including 15 lecturers, 2 tutors and 37 trainees, representing 25 countries.

  10. Renormalization screening and collision-induced quantum interference in dense plasmas

    SciTech Connect

    Jung, Young-Dae; Rasheed, A.; Jamil, M.

    2014-07-15

    The influence of renormalization screening and collision-induced quantum interference in electron-electron collisions is investigated in partially ionized dense hydrogen plasmas. The effective interaction potential with the total spin-states of the collision system is considered to obtain the differential electron-electron scattering cross section. The results show that the renormalization plasma screening effect suppresses the electron-electron scattering cross section, including the quantum interference effect, especially, except for the forward and backward scattering directions. It is also shown that the renormalization plasma screening effect on the scattering cross section decreases with increasing collision energy. However, the renormalization screening effect is found to be important for the forward directions in the scattering cross section neglecting the quantum interference effect. The variations of the renormalization screening and collision-induced quantum interference effects are also discussed.

  11. INFERNO - A better model of atoms in dense plasmas

    NASA Astrophysics Data System (ADS)

    Liberman, D. A.

    1982-03-01

    A self-consistent field model of atoms in dense plasmas has been devised and incorporated in a computer program. In the model there is a uniform positive charge distribution with a hole in it and at the center of the hole an atomic nucleus. There are electrons, in both bound and continuum states, in sufficient number to form an electrically neutral system. The Dirac equation is used so that high Z atoms can be dealt with. A finite temperature is assumed, and a mean field (average atom) approximation is used in statistical averages. Applications have been made to equations of states and to photoabsorption.

  12. Efficient calculation of atomic rate coefficients in dense plasmas

    NASA Astrophysics Data System (ADS)

    Aslanyan, Valentin; Tallents, Greg J.

    2017-03-01

    Modelling electron statistics in a cold, dense plasma by the Fermi-Dirac distribution leads to complications in the calculations of atomic rate coefficients. The Pauli exclusion principle slows down the rate of collisions as electrons must find unoccupied quantum states and adds a further computational cost. Methods to calculate these coefficients by direct numerical integration with a high degree of parallelism are presented. This degree of optimization allows the effects of degeneracy to be incorporated into a time-dependent collisional-radiative model. Example results from such a model are presented.

  13. Nonlinear waves in dense dusty plasmas with high fugacity

    NASA Astrophysics Data System (ADS)

    Rao, N. N.; Shukla, P. K.

    2001-01-01

    Nonlinear propagation of small, but finite, amplitude electrostatic dust waves has been investigated in the low as well as high fugacity regimes by deriving the corresponding Boussinesq equation which, for unidirectional propagation, reduces to the Korteweg-de Vries equation. The dust-acoustic wave (DAW) solitons are shown to correspond to the tenuous (low fugacity) dusty plasmas, while in the dense (high fugacity) regime the solitons are associated with the dust-Coulomb waves (DCWs). Unlike the DAW solitons which are (dust) density compressional and supersonic, the DCW solitons are (dust) density rarefactive and propagate with super-Coulombic speeds.

  14. Electrostatic Waves in Dense Dusty Plasmas with High Fugacity

    NASA Astrophysics Data System (ADS)

    Rao, N. N.

    Propagation of electrostatic dust modes has been reviewed in the light of the concept of dust fugacity defined by f≡4πnd0λD2R, where nd0 and R are the dust number density and the grain size (radius) while the plasma Debye length (λD) is given through λD-2=λDe-2+λDi-2. Dusty plasmas are defined to be tenuous, dilute or dense when f≪1, ˜1, or ≫1, respectively. Attention is focused on “Dust-Acoustic Waves” (DAWs) and “Dust-Coulomb Waves” (DCWs) which exist in the tenuous (f≪1) and the dense (f≫1) regimes, respectively. A simple physical picture of the DCWs has been proposed in terms of an effective pressure called “Coulomb Pressure defined by PC≡nd0qd02/R, where qd0 is the grain charge. In the lowest order, the DCW phase speed is given by ω/k=PC/ρdδ, where ρd≡nd0md is the dust mass density and δ≡ω2/ω1 is the ratio of charging frequencies. Thus, DCWs which are driven by the Coulomb pressure can be considered as the electrostatic analogue of hydromagnetic (Alfvén or magnetoacoustic) modes which are driven by magnetic field pressure. In the dilute regime, the two waves loose their identities and merge into a single mode, which may be called “Dust Charge-Density Wave” (DCDW). When the grains are closest, DCW dispersion relation is identical with that of “Dust-Lattice Waves” (DLWs). Dense dusty plasmas are governed by a new scale-length defined by λR≡1/4πnd0Rδ, which characterizes the effective shielding length due to grain collective interactions. The scale-length λR plays a fundamental role in dense dusty plasmas, which is very similar to that of the Debye length λD in the tenuous regime. The two scale-lengths are related to the fugacity through fδ≡λD2/λR2. The frequency spectrum as well as the damping rates for various dust modes have been analytically obtained, and compared with the numerical solutions of the kinetic (Vlasov) dispersion relation.

  15. INPIStron switched pulsed power for dense plasma pinches

    NASA Technical Reports Server (NTRS)

    Han, Kwang S.; Lee, Ja H.

    1993-01-01

    The inverse plasma switch INPIStron was employed for 10kJ/40kV capacitor bank discharge system to produce focused dense plasmas in hypocycloidal-pinch (HCP) devices. A single unit and an array of multiple HCP's were coupled as the load of the pulsed power circuit. The geometry and switching plasma dynamics were found advantageous and convenient for commutating the large current pulse from the low impedance transmission line to the low impedance plasma load. The pulse power system with a single unit HCP, the system A, was used for production of high temperature plasma focus and its diagnostics. The radially running down plasma dynamics, revealed in image converter photographs, could be simulated by a simple snow-plow model with a correction for plasma resistivity. The system B with an array of 8-HCP units which forms a long coaxial discharge chamber was used for pumping a Ti-sapphire laser. The intense UV emission from the plasma was frequency shifted with dye-solution jacket to match the absorption band of the Ti crystal laser near 500 nm. An untuned laser pulse energy of 0.6 J/pulse was obtained for 6.4 kJ/40 kV discharge, or near 103 times of the explosion limit of conventional flash lamps. For both systems the advantages of the INPIStron were well demonstrated: a single unit is sufficient for a large current (greater than 50 kA) without increasing the system impedance, highly reliable and long life operation and implied scalability for the high power ranges above I(sub peak) = 1 MA and V(sub hold) = 100 kV.

  16. Microwave Plasma Hydrogen Recovery System

    NASA Technical Reports Server (NTRS)

    Atwater, James; Wheeler, Richard, Jr.; Dahl, Roger; Hadley, Neal

    2010-01-01

    A microwave plasma reactor was developed for the recovery of hydrogen contained within waste methane produced by Carbon Dioxide Reduction Assembly (CRA), which reclaims oxygen from CO2. Since half of the H2 reductant used by the CRA is lost as CH4, the ability to reclaim this valuable resource will simplify supply logistics for longterm manned missions. Microwave plasmas provide an extreme thermal environment within a very small and precisely controlled region of space, resulting in very high energy densities at low overall power, and thus can drive high-temperature reactions using equipment that is smaller, lighter, and less power-consuming than traditional fixed-bed and fluidized-bed catalytic reactors. The high energy density provides an economical means to conduct endothermic reactions that become thermodynamically favorable only at very high temperatures. Microwave plasma methods were developed for the effective recovery of H2 using two primary reaction schemes: (1) methane pyrolysis to H2 and solid-phase carbon, and (2) methane oligomerization to H2 and acetylene. While the carbon problem is substantially reduced using plasma methods, it is not completely eliminated. For this reason, advanced methods were developed to promote CH4 oligomerization, which recovers a maximum of 75 percent of the H2 content of methane in a single reactor pass, and virtually eliminates the carbon problem. These methods were embodied in a prototype H2 recovery system capable of sustained high-efficiency operation. NASA can incorporate the innovation into flight hardware systems for deployment in support of future long-duration exploration objectives such as a Space Station retrofit, Lunar outpost, Mars transit, or Mars base. The primary application will be for the recovery of hydrogen lost in the Sabatier process for CO2 reduction to produce water in Exploration Life Support systems. Secondarily, this process may also be used in conjunction with a Sabatier reactor employed to

  17. Beam-driven acceleration in ultra-dense plasma media

    SciTech Connect

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 10{sup 25 }m{sup −3} and 1.6 × 10{sup 28 }m{sup −3} plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers ∼20% higher acceleration gradient by enlarging the channel radius (r) from 0.2 λ{sub p} to 0.6 λ{sub p} in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g., nanotubes) of high electron plasma density.

  18. Beam-driven acceleration in ultra-dense plasma media

    SciTech Connect

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r) from 0.2 Ap to 0.6 .Ap in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.

  19. Beam-driven acceleration in ultra-dense plasma media

    DOE PAGES

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r)more » from 0.2 Ap to 0.6 .Ap in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.« less

  20. Non-LTE modeling of radiatively driven dense plasmas

    NASA Astrophysics Data System (ADS)

    Scott, H. A.

    2017-03-01

    There are now several experimental facilities that use strong X-ray fields to produce plasmas with densities ranging from ˜1 to ˜103 g/cm3. Large laser facilities, such as the National Ignition Facility (NIF) and the Omega laser reach high densities with radiatively driven compression, short-pulse lasers such as XFELs produce solid density plasmas on very short timescales, and the Orion laser facility combines these methods. Despite the high densities, these plasmas can be very far from LTE, due to large radiation fields and/or short timescales, and simulations mostly use collisional-radiative (CR) modeling which has been adapted to handle these conditions. These dense plasmas present challenges to CR modeling. Ionization potential depression (IPD) has received much attention recently as researchers work to understand experimental results from LCLS and Orion [1,2]. However, incorporating IPD into a CR model is only one challenge presented by these conditions. Electron degeneracy and the extent of the state space can also play important roles in the plasma energetics and radiative properties, with effects evident in recent observations [3,4]. We discuss the computational issues associated with these phenomena and methods for handling them.

  1. Experiments on the interaction of heavy ions with dense plasma at GSI-Darmstadt

    NASA Astrophysics Data System (ADS)

    Stöckl, C.; Boine-Frankenheim, O.; Geißel, M.; Roth, M.; Wetzler, H.; Seelig, W.; Iwase, O.; Spiller, P.; Bock, R.; Süß, W.; Hoffmann, D. H. H.

    One of the main objectives of the experimental plasma physics activities at the Gesellschaft für Schwerionenforschung (GSI) are the interaction processes of heavy ions with dense ionized matter. Gas-discharge plasma targets were used for energy loss and charge state measurements in a regime of electron density and temperature up to 10 19 cm -3 and 20 eV, respectively. An improved model of the charge exchange processes in fully ionized hydrogen plasma, taking into account multiple excited electronic configurations which subsequently ionize, has removed the discrepancies of previous theoretical descriptions. The energy loss of the ion beam in partially ionized plasmas such as argon was found to agree very well with our simple theoretical model based on the modified Bethe-Bloch theory. A new setup with a 100 J/5 GW Nd-glass laser now provides access to density ranges up to 10 21 cm -3 and temperatures of up to 100 eV. First results of interaction experiments with laser-produced plasma are presented. To fully exploit the experimental possibilities of the new laser-plasma setup both improved charge state detection systems and better plasma diagnostics are indispensable. Present developments and future possibilities in these fields are presented. This paper summarizes the following contributions: Interaction of heavy-ion beams with laser plasma by C. Stöckl et al. Energy Loss of Heavy Ions in a laser-produced plasma by M. Roth et al. Charge state measurements of heavy ions passing a laser produced plasma with high time resolution by W. Süß et al. Plasma diagnostics for laser-produced plasma by O. Iwase et al. Future possibilities of plasma diagnostics at GSI by M. Geißel et al.

  2. Hydrogen plasma dynamics in the spherical theta pinch plasma target for heavy ion stripping

    SciTech Connect

    Loisch, G.; Jacoby, J.; Xu, G.; Blazevic, A.; Cihodariu-Ionita, B.

    2015-05-15

    Due to the superior ability of dense and highly ionised plasmas to ionise penetrating heavy ion beams to degrees beyond those reachable by common gas strippers, many experiments have been performed to find suitable plasma generators for this application. In the field of gas discharges, mainly z-pinch devices have been investigated so far, which are known to be limited by the nonlinear focusing effects of the plasma columns sustaining current and by electrode erosion. The spherical theta pinch has therefore been proposed as a substitution for the z-pinch, promising progress by inductive rather than capacitive coupling and displacement of the outer magnetic field by the dense, diamagnetic discharge plasma. As yet mainly experiments with argon/hydrogen mixture gas have been performed, which is not suitable for the application as a plasma stripper, this paper describes the first detailed analysis of the plasma parameters and dynamics of a hydrogen plasma created by the spherical theta pinch. These include the time integrated and time resolved electron density, the dynamics of the plasma in the discharge vessel, the comparison with the argon dominated plasma, and an outlook to reachable characteristics with similar devices.

  3. Charge exchange between two nearest neighbour ions immersed in a dense plasma

    NASA Astrophysics Data System (ADS)

    Sauvan, P.; Angelo, P.; Derfoul, H.; Leboucher-Dalimier, E.; Devdariani, A.; Calisti, A.; Talin, B.

    1999-04-01

    In dense plasmas the quasimolecular model is relevant to describe the radiative properties: two nearest neighbor ions remain close to each other during a time scale of the order of the emission time. Within the frame of a quasistatic approach it has been shown that hydrogen-like spectral line shapes can exhibit satellite-like features. In this work we present the effect on the line shapes of the dynamical collision between the two ions exchanging transiently their bound electron. This model is suitable for the description of the core, the wings and the red satellite-like features. It is post-processed to the self consistent code (IDEFIX) giving the adiabatic transition energies and the oscillator strengths for the transient molecule immersed in a dense free electron bath. It is shown that the positions of the satellites are insensitive to the dynamics of the ion-ion collision. Results for fluorine Lyβ are presented.

  4. X-UV Index of Refraction of Dense and Hot Plasmas.

    PubMed

    Benattar, R; Galos, C; Ney, P

    1995-01-01

    In a dense and hot plasma the refractive index in the X-UV range takes into account not only the effect of free electrons, but also the effect of electrons bound by atoms. The refractive index is calculated by the Kramer-Kronig relations using the total opacity of the medium including bound-bound, free-bound, and free-free atomic transitions. A simple method of calculation of the emission and absorption coefficients is presented. These parameters are of great interest when one wants to study radiative transfer in a dense and hot material. The computer program used allows one to obtain either in LTE or in NLTE the values of these coefficients for every material and for a wide range of mass density and temperature, using a screened hydrogenic model. Applications are presented first to generate opacity tables and second to generate the index of refraction of aluminum for a wide range of mass density and temperature.

  5. Dense plasma focus (DPF) accelerated non radio isotopic radiological source

    DOEpatents

    Rusnak, Brian; Tang, Vincent

    2017-01-31

    A non-radio-isotopic radiological source using a dense plasma focus (DPF) to produce an intense z-pinch plasma from a gas, such as helium, and which accelerates charged particles, such as generated from the gas or injected from an external source, into a target positioned along an acceleration axis and of a type known to emit ionizing radiation when impinged by the type of accelerated charged particles. In a preferred embodiment, helium gas is used to produce a DPF-accelerated He2+ ion beam to a beryllium target, to produce neutron emission having a similar energy spectrum as a radio-isotopic AmBe neutron source. Furthermore, multiple DPFs may be stacked to provide staged acceleration of charged particles for enhancing energy, tunability, and control of the source.

  6. Hydrogen Plasma Processing of Iron Ore

    NASA Astrophysics Data System (ADS)

    Sabat, Kali Charan; Murphy, Anthony B.

    2017-03-01

    Iron is currently produced by carbothermic reduction of oxide ores. This is a multiple-stage process that requires large-scale equipment and high capital investment, and produces large amounts of CO2. An alternative to carbothermic reduction is reduction using a hydrogen plasma, which comprises vibrationally excited molecular, atomic, and ionic states of hydrogen, all of which can reduce iron oxides, even at low temperatures. Besides the thermodynamic and kinetic advantages of a hydrogen plasma, the byproduct of the reaction is water, which does not pose any environmental problems. A review of the theory and practice of iron ore reduction using a hydrogen plasma is presented. The thermodynamic and kinetic aspects are considered, with molecular, atomic and ionic hydrogen considered separately. The importance of vibrationally excited hydrogen molecules in overcoming the activation energy barriers, and in transferring energy to the iron oxide, is emphasized. Both thermal and nonthermal plasmas are considered. The thermophysical properties of hydrogen and argon-hydrogen plasmas are discussed, and their influence on the constriction and flow in the of arc plasmas is considered. The published R&D on hydrogen plasma reduction of iron oxide is reviewed, with both the reduction of molten iron ore and in-flight reduction of iron ore particles being considered. Finally, the technical and economic feasibility of the process are discussed. It is shown that hydrogen plasma processing requires less energy than carbothermic reduction, mainly because pelletization, sintering, and cokemaking are not required. Moreover, the formation of the greenhouse gas CO2 as a byproduct is avoided. In-flight reduction has the potential for a throughput at least equivalent to the blast furnace process. It is concluded that hydrogen plasma reduction of iron ore is a potentially attractive alternative to standard methods.

  7. Equation of state of dense plasmas with pseudoatom molecular dynamics.

    PubMed

    Starrett, C E; Saumon, D

    2016-06-01

    We present an approximation for calculating the equation of state (EOS) of warm and hot dense matter that is built on the previously published pseudoatom molecular dynamics (PAMD) model of dense plasmas [Starrett et al., Phys. Rev. E 91, 013104 (2015)PLEEE81539-375510.1103/PhysRevE.91.013104]. While the EOS calculation with PAMD was previously limited to orbital-free density functional theory (DFT), the new approximation presented here allows a Kohn-Sham DFT treatment of the electrons. The resulting EOS thus includes a quantum mechanical treatment of the electrons with a self-consistent model of the ionic structure, while remaining tractable at high temperatures. The method is validated by comparisons with pressures from ab initio simulations of Be, Al, Si, and Fe. The EOS in the Thomas-Fermi approximation shows remarkable thermodynamic consistency over a wide range of temperatures for aluminum. We calculate the principal Hugoniots of aluminum and silicon up to 500 eV. We find that the ionic structure of the plasma has a modest effect that peaks at temperatures of a few eV and that the features arising from the electronic structure agree well with ab initio simulations.

  8. Observations of strong ion-ion correlations in dense plasmas

    SciTech Connect

    Ma, T. Pak, A.; Landen, O. L.; Le Pape, S.; Turnbull, D.; Döppner, T.; Fletcher, L.; Galtier, E.; Hastings, J.; Lee, H. J.; Nagler, B.; Glenzer, S. H.; Chapman, D. A.; Falcone, R. W.; Fortmann, C.; Gericke, D. O.; Gregori, G.; White, T. G.; Neumayer, P.; Vorberger, J.; and others

    2014-05-15

    Using simultaneous spectrally, angularly, and temporally resolved x-ray scattering, we measure the pronounced ion-ion correlation peak in a strongly coupled plasma. Laser-driven shock-compressed aluminum at ∼3× solid density is probed with high-energy photons at 17.9 keV created by molybdenum He-α emission in a laser-driven plasma source. The measured elastic scattering feature shows a well-pronounced correlation peak at a wave vector of k=4Å{sup −1}. The magnitude of this correlation peak cannot be described by standard plasma theories employing a linear screened Coulomb potential. Advanced models, including a strong short-range repulsion due to the inner structure of the aluminum ions are however in good agreement with the scattering data. These studies have demonstrated a new highly accurate diagnostic technique to directly measure the state of compression and the ion-ion correlations. We have since applied this new method in single-shot wave-number resolved S(k) measurements to characterize the physical properties of dense plasmas.

  9. The One Component Plasma: a paradigm for Warm Dense Matter

    NASA Astrophysics Data System (ADS)

    Clerouin, Jean; Arnault, Philippe; Ticknor, Christopher; Kress, Joel; Collins, Lee

    2015-11-01

    We study the static and dynamical properties of plasmas using orbital free molecular dynamics simulations in the hot and dense regime. Because such simulations do not make any assumptions on ionization and screening we call them real plasmas. Thanks to a systematic comparison with the one component plasma (OCP) structure we define an effective OCP (eOCP) from which a coupling parameter Γe and an effective ionization Qe are deduced. It is shown that, while eOCP is relevant for the short-range structure at high temperatures, screening manifests itself at long range. Dynamical properties are characterized by different frequencies of oscillation that can be reconciled using a renormalized mass. Since the short time scales and the relaxation times are similar, transport properties can be derived through a connection to the eOCP. Collective modes confirm that screening is important at low wavenumber k (long distance) allowing for the definition of a sound speed, but that eOCP behavior is recovered at high k (short distance) conditions.

  10. Optimizing Dense Plasma Focus Neutron Yields with Fast Gas Jets

    NASA Astrophysics Data System (ADS)

    McMahon, Matthew; Kueny, Christopher; Stein, Elizabeth; Link, Anthony; Schmidt, Andrea

    2016-10-01

    We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high density jet models fast gas puffs which allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of the jet compared to the background fill increases we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration is explored. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  11. Fully kinetic simulations of megajoule-scale dense plasma focus

    SciTech Connect

    Schmidt, A.; Link, A.; Tang, V.; Halvorson, C.; May, M.; Welch, D.; Meehan, B. T.; Hagen, E. C.

    2014-10-15

    Dense plasma focus (DPF) Z-pinch devices are sources of copious high energy electrons and ions, x-rays, and neutrons. Megajoule-scale DPFs can generate 10{sup 12} neutrons per pulse in deuterium gas through a combination of thermonuclear and beam-target fusion. However, the details of the neutron production are not fully understood and past optimization efforts of these devices have been largely empirical. Previously, we reported on the first fully kinetic simulations of a kilojoule-scale DPF and demonstrated that both kinetic ions and kinetic electrons are needed to reproduce experimentally observed features, such as charged-particle beam formation and anomalous resistivity. Here, we present the first fully kinetic simulation of a MegaJoule DPF, with predicted ion and neutron spectra, neutron anisotropy, neutron spot size, and time history of neutron production. The total yield predicted by the simulation is in agreement with measured values, validating the kinetic model in a second energy regime.

  12. 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.

  13. MHD modeling of dense plasma focus electrode shape variation

    NASA Astrophysics Data System (ADS)

    McLean, Harry; Hartman, Charles; Schmidt, Andrea; Tang, Vincent; Link, Anthony; Ellsworth, Jen; Reisman, David

    2013-10-01

    The dense plasma focus (DPF) is a very simple device physically, but results to date indicate that very extensive physics is needed to understand the details of operation, especially during the final pinch where kinetic effects become very important. Nevertheless, the overall effects of electrode geometry, electrode size, and drive circuit parameters can be informed efficiently using MHD fluid codes, especially in the run-down phase before the final pinch. These kinds of results can then guide subsequent, more detailed fully kinetic modeling efforts. We report on resistive 2-d MHD modeling results applying the TRAC-II code to the DPF with an emphasis on varying anode and cathode shape. Drive circuit variations are handled in the code using a self-consistent circuit model for the external capacitor bank since the device impedance is strongly coupled to the internal plasma physics. Electrode shape is characterized by the ratio of inner diameter to outer diameter, length to diameter, and various parameterizations for tapering. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  14. ALEGRA-HEDP simulations of the dense plasma focus.

    SciTech Connect

    Flicker, Dawn G.; Kueny, Christopher S.; Rose, David V.

    2009-09-01

    We have carried out 2D simulations of three dense plasma focus (DPF) devices using the ALEGRA-HEDP code and validated the results against experiments. The three devices included two Mather-type machines described by Bernard et. al. and the Tallboy device currently in operation at NSTec in North Las Vegas. We present simulation results and compare to detailed plasma measurements for one Bernard device and to current and neutron yields for all three. We also describe a new ALEGRA capability to import data from particle-in-cell calculations of initial gas breakdown, which will allow the first ever simulations of DPF operation from the beginning of the voltage discharge to the pinch phase for arbitrary operating conditions and without assumptions about the early sheath structure. The next step in understanding DPF pinch physics must be three-dimensional modeling of conditions going into the pinch, and we have just launched our first 3D simulation of the best-diagnosed Bernard device.

  15. Unified concept of effective one component plasma for hot dense plasmas

    SciTech Connect

    Clerouin, Jean; Arnault, Philippe; Ticknor, Christopher; Kress, Joel D.; Collins, Lee A.

    2016-03-17

    Orbital-free molecular dynamics simulations are used to benchmark two popular models for hot dense plasmas: the one component plasma (OCP) and the Yukawa model. A unified concept emerges where an effective OCP (EOCP) is constructed from the short-range structure of the plasma. An unambiguous ionization and the screening length can be defined and used for a Yukawa system, which reproduces the long-range structure with finite compressibility. Similarly, the dispersion relation of longitudinal waves is consistent with the screened model at vanishing wave number but merges with the OCP at high wave number. Additionally, the EOCP reproduces the overall relaxation time scales of the correlation functions associated with ionic motion. Lastly, in the hot dense regime, this unified concept of EOCP can be fruitfully applied to deduce properties such as the equation of state, ionic transport coefficients, and the ion feature in x-ray Thomson scattering experiments.

  16. Unified concept of effective one component plasma for hot dense plasmas

    DOE PAGES

    Clerouin, Jean; Arnault, Philippe; Ticknor, Christopher; ...

    2016-03-17

    Orbital-free molecular dynamics simulations are used to benchmark two popular models for hot dense plasmas: the one component plasma (OCP) and the Yukawa model. A unified concept emerges where an effective OCP (EOCP) is constructed from the short-range structure of the plasma. An unambiguous ionization and the screening length can be defined and used for a Yukawa system, which reproduces the long-range structure with finite compressibility. Similarly, the dispersion relation of longitudinal waves is consistent with the screened model at vanishing wave number but merges with the OCP at high wave number. Additionally, the EOCP reproduces the overall relaxation timemore » scales of the correlation functions associated with ionic motion. Lastly, in the hot dense regime, this unified concept of EOCP can be fruitfully applied to deduce properties such as the equation of state, ionic transport coefficients, and the ion feature in x-ray Thomson scattering experiments.« less

  17. Thermodynamic properties of hydrogen-helium plasmas.

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1972-01-01

    Calculation of the thermodynamic properties of an atomic hydrogen-helium plasma for postulated conditions present in a stagnation shock layer of a spacecraft entering the atmosphere of Jupiter. These properties can be used to evaluate transport properties, to calculate convective heating, and to investigate nonequilibrium behavior. The calculations have been made for temperatures from 10,000 to 100,000 K, densities of 10 to the minus 7th and .00001 g cu cm, and three plasma compositions: pure hydrogen, 50% hydrogen/50% helium, and pure helium. The shock layer plasma consists of electrons, protons, atomic hydrogen, atomic helium, singly ionized helium, and doubly atomized helium. The thermodynamic properties which have been investigated are: pressure, average molecular weight, internal energy, enthalpy, entropy, specific heat, and isentropic speed of sound. A consistent model was used for the reduction of the ionization potential in the calculation of the partition functions.

  18. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    NASA Astrophysics Data System (ADS)

    Dey, R.; Roy, A. C.

    2013-07-01

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Zi = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×108 V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  19. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    SciTech Connect

    Dey, R.; Roy, A. C.

    2013-07-15

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Z{sub i} = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×10{sup 8} V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  20. Study on the Polarity Riddle of the Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Jiang, Sheng; Link, Anthony; Higginson, Drew; Schmidt, Andrea

    2016-10-01

    The dense plasma focus (DPF) Z-pinch devices are capable of producing intense pulses of X-rays and neutrons, thus can serve as portable sources for active interrogation. DPF devices are normally operated with the inner electrode as anode. It has been found that interchanging the polarity of the electrodes can cause orders of magnitude decrease in the neutron yield1. The reason for this severe decay remains unclear. Here we use the particle-in-cell (PIC) code LSP2,3 to model a portable DPF with both polarities. The filling gas is deuterium. The simulations are run in the fluid mode for the rundown phase and are switched to kinetic to capture the anomalous resistivity and beam acceleration process during the pinch. The difference in the shape of the sheath, the voltage and current traces, and the electric and magnetic fields in the pinch region due to different polarities all have great effects on the deuteron ion spectrum, which further determines the neutron yield. A detailed comparison will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (15-ERD-034) at LLNL.

  1. Laser induced focusing for over-dense plasma beams

    SciTech Connect

    Schmidt, Peter; Boine-Frankenheim, Oliver; Mulser, Peter

    2015-09-15

    The capability of ion acceleration with high power, pulsed lasers has become an active field of research in the past years. In this context, the radiation pressure acceleration (RPA) mechanism has been the topic of numerous theoretical and experimental publications. Within that mechanism, a high power, pulsed laser beam hits a thin film target. In contrast to the target normal sheath acceleration, the entire film target is accelerated as a bulk by the radiation pressure of the laser. Simulations predict heavy ion beams with kinetic energy up to GeV, as well as solid body densities. However, there are several effects which limit the efficiency of the RPA: On the one hand, the Rayleigh-Taylor-instability limits the predicted density. On the other hand, conventional accelerator elements, such as magnetic focusing devices are too bulky to be installed right after the target. Therefore, we present a new beam transport method, suitable for RPA-like/over-dense plasma beams: laser induced focusing.

  2. Hydrogen ionic plasma generated using Al plasma grid

    NASA Astrophysics Data System (ADS)

    Oohara, W.; Anegawa, N.; Egawa, M.; Kawata, K.; Kamikawa, T.

    2016-08-01

    Negative hydrogen ions are produced in the apertures of a plasma grid made of aluminum under the irradiation of positive ions, generating an ionic plasma consisting of positive and negative ions. The saturation current ratio obtained using a Langmuir probe reflects the existence ratio of electrons and is found to increase in connection with the diffusion of the ionic plasma. The local increment of the current ratio suggests the collapse of negative ions and the replacement of detached electrons.

  3. Fast and accurate quantum molecular dynamics of dense plasmas across temperature regimes

    SciTech Connect

    Sjostrom, Travis; Daligault, Jerome

    2014-10-10

    Here, we develop and implement a new quantum molecular dynamics approximation that allows fast and accurate simulations of dense plasmas from cold to hot conditions. The method is based on a carefully designed orbital-free implementation of density functional theory. The results for hydrogen and aluminum are in very good agreement with Kohn-Sham (orbital-based) density functional theory and path integral Monte Carlo calculations for microscopic features such as the electron density as well as the equation of state. The present approach does not scale with temperature and hence extends to higher temperatures than is accessible in the Kohn-Sham method and lower temperatures than is accessible by path integral Monte Carlo calculations, while being significantly less computationally expensive than either of those two methods.

  4. Fast and accurate quantum molecular dynamics of dense plasmas across temperature regimes

    DOE PAGES

    Sjostrom, Travis; Daligault, Jerome

    2014-10-10

    Here, we develop and implement a new quantum molecular dynamics approximation that allows fast and accurate simulations of dense plasmas from cold to hot conditions. The method is based on a carefully designed orbital-free implementation of density functional theory. The results for hydrogen and aluminum are in very good agreement with Kohn-Sham (orbital-based) density functional theory and path integral Monte Carlo calculations for microscopic features such as the electron density as well as the equation of state. The present approach does not scale with temperature and hence extends to higher temperatures than is accessible in the Kohn-Sham method and lowermore » temperatures than is accessible by path integral Monte Carlo calculations, while being significantly less computationally expensive than either of those two methods.« less

  5. Quantum diffraction effects on the atomic polarization collision in partially ionized dense plasmas

    SciTech Connect

    Jung, Young-Dae

    2014-04-15

    The influence of quantum diffraction on the electron-atom polarization collision process is investigated in partially ionized dense plasmas. The pseudopotential model and eikonal method are employed to obtain the eikonal phase shift and eikonal cross section as functions of the impact parameter, collision energy, Debye length, electron de Broglie wavelength, and atomic polarizability. The results show that the eikonal phase shift for the electron-hydrogen atom polarization collision decreases with an increase of the electron de Broglie wavelength. It is important to note that the influence of quantum diffraction produces the repulsive part in the electron-atom polarization interaction. It is also found that the quantum diffraction effect enhances the differential eikonal cross section. Additionally, the total eikonal cross section decreases with increasing electron de Broglie wavelength. The variations of the eikonal cross section due to the influence of finite size of the de Broglie wavelength and Debye radius are also discussed.

  6. The metallization and superconductivity of dense hydrogen sulfide

    SciTech Connect

    Li, Yinwei Hao, Jian; Li, Yanling; Liu, Hanyu; Ma, Yanming

    2014-05-07

    Hydrogen sulfide (H{sub 2}S) is a prototype molecular system and a sister molecule of water (H{sub 2}O). The phase diagram of solid H{sub 2}S at high pressures remains largely unexplored arising from the challenges in dealing with the pressure-induced weakening of S–H bond and larger atomic core difference between H and S. Metallization is yet achieved for H{sub 2}O, but it was observed for H{sub 2}S above 96 GPa. However, the metallic structure of H{sub 2}S remains elusive, greatly impeding the understanding of its metallicity and the potential superconductivity. We have performed an extensive structural study on solid H{sub 2}S at pressure ranges of 10–200 GPa through an unbiased structure prediction method based on particle swarm optimization algorithm. Besides the findings of candidate structures for nonmetallic phases IV and V, we are able to establish stable metallic structures violating an earlier proposal of elemental decomposition into sulfur and hydrogen [R. Rousseau, M. Boero, M. Bernasconi, M. Parrinello, and K. Terakura, Phys. Rev. Lett. 85, 1254 (2000)]. Our study unravels a superconductive potential of metallic H{sub 2}S with an estimated maximal transition temperature of ∼80 K at 160 GPa, higher than those predicted for most archetypal hydrogen-containing compounds (e.g., SiH{sub 4}, GeH{sub 4}, etc.)

  7. The metallization and superconductivity of dense hydrogen sulfide

    NASA Astrophysics Data System (ADS)

    Li, Yinwei; Hao, Jian; Liu, Hanyu; Li, Yanling; Ma, Yanming

    2014-05-01

    Hydrogen sulfide (H2S) is a prototype molecular system and a sister molecule of water (H2O). The phase diagram of solid H2S at high pressures remains largely unexplored arising from the challenges in dealing with the pressure-induced weakening of S-H bond and larger atomic core difference between H and S. Metallization is yet achieved for H2O, but it was observed for H2S above 96 GPa. However, the metallic structure of H2S remains elusive, greatly impeding the understanding of its metallicity and the potential superconductivity. We have performed an extensive structural study on solid H2S at pressure ranges of 10-200 GPa through an unbiased structure prediction method based on particle swarm optimization algorithm. Besides the findings of candidate structures for nonmetallic phases IV and V, we are able to establish stable metallic structures violating an earlier proposal of elemental decomposition into sulfur and hydrogen [R. Rousseau, M. Boero, M. Bernasconi, M. Parrinello, and K. Terakura, Phys. Rev. Lett. 85, 1254 (2000)]. Our study unravels a superconductive potential of metallic H2S with an estimated maximal transition temperature of ˜80 K at 160 GPa, higher than those predicted for most archetypal hydrogen-containing compounds (e.g., SiH4, GeH4, etc.).

  8. Semimetallic dense hydrogen above 260 GPa

    PubMed Central

    Lebègue, Sébastien; Araujo, Carlos Moyses; Kim, Duck Young; Ramzan, Muhammad; Mao, Ho-kwang; Ahuja, Rajeev

    2012-01-01

    Being the lightest and the most abundant element in the universe, hydrogen is fascinating to physicists. In particular, the conditions of its metallization associated with a possible superconducting state at high temperature have been a matter of much debate in the scientific community, and progress in this field is strongly correlated with the advancements in theoretical methods and experimental techniques. Recently, the existence of hydrogen in a metallic state was reported experimentally at room temperature under a pressure of 260–270 GPa, but was shortly after that disputed in the light of more experiments, finding either a semimetal or a transition to an other phase. With the aim to reconcile the different interpretations proposed, we propose by combining several computational techniques, such as density functional theory and the GW approximation, that phase III at ambient temperature of hydrogen is the Cmca-12 phase, which becomes a semimetal at 260 GPa . From phonon calculations, we demonstrate it to be dynamically stable; calculated electron–phonon coupling is rather weak and therefore this phase is not expected to be a high-temperature superconductor. PMID:22665782

  9. Quantum simulation of structure, transport properties, and melting in dense hydrogen

    NASA Astrophysics Data System (ADS)

    Kang, Dongdong; Dai, Jiayu; Yuan, Jianmin

    2016-10-01

    Due to the low mass, hydrogen exhibits significant nuclear quantum effects (NQEs), especially under low temperatures and high pressures. NQEs on structure and transport properties of dense liquid hydrogen under extreme conditions are investigated using the improved centroid path integral molecular dynamics (PIMD) simulations. The results show that with the inclusion of NQEs, the radial distribution functions are obviously broadened. The self-diffusion is largely higher while the shear viscosity is notably lower than the results of without the inclusion of NQEs due to the lower collision cross sections even when the NQEs have little effects on the static structures. The electrical conductivity is also significantly affected by NQEs. Quantum nuclear character induces complex behaviors for ionic transport properties of dense liquid hydrogen. In addition, the melting temperature of dense hydrogen is also investigated using the two-phase approach based on the PIMD with the Yukawa potential describing the interaction between ions. The results show that the NQEs have a significant impact on the melting of dense hydrogen, which largely lower the melting temperature by 10% at the density range of 10-1000 g/cm3.

  10. Equation of state and phase diagram of dense hydrogen

    NASA Technical Reports Server (NTRS)

    Kerley, G. I.

    1972-01-01

    The equation of state of hydrogen was calculated for specific volumes ranging from 0.01 to 0.0001 cm3/mole and for temperatures ranging from 200 to 1 million K. Three phases are considered: the molecular solid, the metallic solid and the fluid. Chemical equilibrium between molecules, atoms, ions and electrons is considered in calculating the properties of the fluid phase. Transitions between the three phases will be discussed. The triple point, where the three phases coexist, is calculated to occur at 2.3 Mbar and 1679 K. At higher temperatures and pressures, the molecular solid is unstable.

  11. The effects of ionization potential depression on the spectra emitted by hot dense aluminium plasmas

    NASA Astrophysics Data System (ADS)

    Preston, Thomas R.; Vinko, Sam M.; Ciricosta, Orlando; Chung, Hyun-Kyung; Lee, Richard W.; Wark, Justin S.

    2013-06-01

    Recent experiments at the Linac Coherent Light Source (LCLS) X-ray Free-Electron-Laser (FEL) have demonstrated that the standard model used for simulating ionization potential depression (IPD) in a plasma (the Stewart-Pyatt (SP) model, J.C. Stewart and K.D. Pyatt Jr., Astrophysical Journal 144 (1966) 1203) considerably underestimates the degree of IPD in a solid density aluminium plasma at temperatures up to 200 eV. In contrast, good agreement with the experimental data was found by use of a modified Ecker-Kröll (mEK) model (G. Ecker and W. Kröll, Physics of Fluids 6 (1963) 62-69). We present here detailed simulations, using the FLYCHK code, of the predicted spectra from hot dense, hydrogenic and helium-like aluminium plasmas ranging in densities from 0.1 to 4 times solid density, and at temperatures up to 1000 eV. Importantly, we find that the greater IPDs predicted by the mEK model result in the loss of the n = 3 states for the hydrogenic ions for all densities above ≈0.8 times solid density, and for the helium-like ions above ≈0.65 solid density. Therefore, we posit that if the mEK model holds at these higher temperatures, the temperature of solid density highly-charged aluminium plasmas cannot be determined by using spectral features associated with the n = 3 principal quantum number, and propose a re-evaluation of previous experimental data where high densities have been inferred from the spectra, and the SP model has been used.

  12. Dense magnetized plasma associated with a fast radio burst

    NASA Astrophysics Data System (ADS)

    Masui, Kiyoshi; Lin, Hsiu-Hsien; Sievers, Jonathan; Anderson, Christopher J.; Chang, Tzu-Ching; Chen, Xuelei; Ganguly, Apratim; Jarvis, Miranda; Kuo, Cheng-Yu; Li, Yi-Chao; Liao, Yu-Wei; McLaughlin, Maura; Pen, Ue-Li; Peterson, Jeffrey B.; Roman, Alexander; Timbie, Peter T.; Voytek, Tabitha; Yadav, Jaswant K.

    2015-12-01

    Fast radio bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1 (refs 10 and 11). These parameters are consistent with a wide range of source models. One fast burst revealed circular polarization of the radio emission, but no linear polarization was detected, and hence no Faraday rotation measure could be determined. Here we report the examination of archival data revealing Faraday rotation in the fast radio burst FRB 110523. Its radio flux and dispersion measure are consistent with values from previously reported bursts and, accounting for a Galactic contribution to the dispersion and using a model of intergalactic electron density, we place the source at a maximum redshift of 0.5. The burst has a much higher rotation measure than expected for this line of sight through the Milky Way and the intergalactic medium, indicating magnetization in the vicinity of the source itself or within a host galaxy. The pulse was scattered by two distinct plasma screens during propagation, which requires either a dense nebula associated with the source or a location within the central region of its host galaxy. The detection in this instance of magnetization and scattering that are both local to the source favours models involving young stellar populations such as magnetars over models involving the mergers of older neutron stars, which are more likely to be located in low-density regions of the host galaxy.

  13. Dense magnetized plasma associated with a fast radio burst.

    PubMed

    Masui, Kiyoshi; Lin, Hsiu-Hsien; Sievers, Jonathan; Anderson, Christopher J; Chang, Tzu-Ching; Chen, Xuelei; Ganguly, Apratim; Jarvis, Miranda; Kuo, Cheng-Yu; Li, Yi-Chao; Liao, Yu-Wei; McLaughlin, Maura; Pen, Ue-Li; Peterson, Jeffrey B; Roman, Alexander; Timbie, Peter T; Voytek, Tabitha; Yadav, Jaswant K

    2015-12-24

    Fast radio bursts are bright, unresolved, non-repeating, broadband, millisecond flashes, found primarily at high Galactic latitudes, with dispersion measures much larger than expected for a Galactic source. The inferred all-sky burst rate is comparable to the core-collapse supernova rate out to redshift 0.5. If the observed dispersion measures are assumed to be dominated by the intergalactic medium, the sources are at cosmological distances with redshifts of 0.2 to 1 (refs 10 and 11). These parameters are consistent with a wide range of source models. One fast burst revealed circular polarization of the radio emission, but no linear polarization was detected, and hence no Faraday rotation measure could be determined. Here we report the examination of archival data revealing Faraday rotation in the fast radio burst FRB 110523. Its radio flux and dispersion measure are consistent with values from previously reported bursts and, accounting for a Galactic contribution to the dispersion and using a model of intergalactic electron density, we place the source at a maximum redshift of 0.5. The burst has a much higher rotation measure than expected for this line of sight through the Milky Way and the intergalactic medium, indicating magnetization in the vicinity of the source itself or within a host galaxy. The pulse was scattered by two distinct plasma screens during propagation, which requires either a dense nebula associated with the source or a location within the central region of its host galaxy. The detection in this instance of magnetization and scattering that are both local to the source favours models involving young stellar populations such as magnetars over models involving the mergers of older neutron stars, which are more likely to be located in low-density regions of the host galaxy.

  14. 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.

  15. Raman measurements of phase transitions in dense solid hydrogen and deuterium to 325 GPa

    PubMed Central

    Zha, Chang-sheng; Cohen, R. E.; Mao, Ho-kwang; Hemley, Russell J.

    2014-01-01

    Raman spectroscopy of dense hydrogen and deuterium performed to 325 GPa at 300 K reveals previously unidentified transitions. Detailed analysis of the spectra from multiple experimental runs, together with comparison with previous infrared and Raman measurements, provides information on structural modifications of hydrogen as a function of density through the I–III–IV transition sequence, beginning near 200 GPa at 300 K. The data suggest that the transition sequence at these temperatures proceeds by formation of disordered stacking of molecular and distorted layers. Weaker spectral changes are observed at 250, 285, and 300 GPa, that are characterized by discontinuities in pressure shifts of Raman frequencies, and changes in intensities and linewidths. The results indicate changes in structure and bonding, molecular orientational order, and electronic structure of dense hydrogen at these conditions. The data suggest the existence of new phases, either variations of phase IV, or altogether new structures. PMID:24639543

  16. Hydrogen desorption kinetics for aqueous hydrogen fluoride and remote hydrogen plasma processed silicon (001) surfaces

    SciTech Connect

    King, Sean W. Davis, Robert F.; Carter, Richard J.; Schneider, Thomas P.; Nemanich, Robert J.

    2015-09-15

    The desorption kinetics of molecular hydrogen (H{sub 2}) from silicon (001) surfaces exposed to aqueous hydrogen fluoride and remote hydrogen plasmas were examined using temperature programmed desorption. Multiple H{sub 2} desorption states were observed and attributed to surface monohydride (SiH), di/trihydride (SiH{sub 2/3}), and hydroxide (SiOH) species, subsurface hydrogen trapped at defects, and hydrogen evolved during the desorption of surface oxides. The observed surface hydride species were dependent on the surface temperature during hydrogen plasma exposure with mono, di, and trihydride species being observed after low temperature exposure (150 °C), while predominantly monohydride species were observed after higher temperature exposure (450 °C). The ratio of surface versus subsurface H{sub 2} desorption was also found to be dependent on the substrate temperature with 150 °C remote hydrogen plasma exposure generally leading to more H{sub 2} evolved from subsurface states and 450 °C exposure leading to more H{sub 2} desorption from surface SiH{sub x} species. Additional surface desorption states were observed, which were attributed to H{sub 2} desorption from Si (111) facets formed as a result of surface etching by the remote hydrogen plasma or aqueous hydrogen fluoride treatment. The kinetics of surface H{sub 2} desorption were found to be in excellent agreement with prior investigations of silicon surfaces exposed to thermally generated atomic hydrogen.

  17. First experimental demonstration of magnetic-field assisted fast heating of a dense plasma core

    NASA Astrophysics Data System (ADS)

    Fujioka, Shinsuke; Sakata, Shohei; Lee, Seung Ho; Matsuo, Kazuki; Sawada, Hiroshi; Iwasa, Yuki; Law, King Fai Farley; Morita, Hitoki; Kojima, Sadaoki; Abe, Yuki; Yao, Akira; Hata, Masayasu; Johzaki, Tomoyuki; Sunahara, Atsushi; Ozaki, Tetsuo; Sakagami, Hitoshi; Morace, Alessio; Arikawa, Yasunobu; Yogo, Akifumi; Nishimura, Hiroaki; Nakai, Mitsuo; Shiraga, Hiroyuki; Sentoku, Yasuhiko; Nagatomo, Hideo; Azechi, Hiroshi; Firex Project Team

    2016-10-01

    Fast heating of a dense plasma core by an energetic electron beam is being studied on GEKKO-LFEX laser facility. Here, we introduce a laser-driven kilo-tesla external magnetic field to guide the diverging electron beam to the dense plasma core. This involve placing a spherical target in the magnetic field, compressing it with the GEKKO-XII laser beams and then using the LFEX laser beams injected into the dense plasma to generate the electron beam which do the fast heating. Cu-Ka emission is used to visualize transport or heating processes of a dense plasma. X-ray spectrum from a highly ionized Cu ions indicates several keV of the temperature increment induced by the LFEX.

  18. Novel dense membrane for hydrogen separation for energy applications

    SciTech Connect

    Bandopadhyay, Sukumar; Balachandran, Uthamalingam; Nag, Nagendra

    2013-10-24

    The main objectives of this project are: (1) Characterization of the thermo mechanical properties of the novel dense HTM bulk sample; (2) Development of a correlation among the intrinsic factors (such as grain size and phase distribution), and the extrinsic factors (such as temperature and atmosphere) and the thermo-mechanical properties (such as strengths and stress) to predict the performance of a HTM system (HTM membrane and porous substrate) ; and (3) Evaluation of the stability of the novel HTM membrane and its property correlations after thermal cycling. Based on all results and analysis of the thermo mechanical properties for the HTM cermet bulk samples, several important conclusions were made. The mean σfs at room temperature is approximately 356 MPa for the HTM cermet. The mean σfs value decreases to 284 MPa as the temperature increases to 850?C. The Difference difference in atmosphere, such as air or N2, had an insignificant effect on the flexural strength values at 850?C for the HTM cermet. The HTM cermet samples at room temperature and at 500?C fractured without any significant plastic deformation. Whereas, at 850?C, the HTM cermet samples fractured, preceded by an extensive plastic deformation. It seems that the HTM cermet behaves more like an elastic material such as a nonmetal ceramic at the room temperature, and more like a ductile material at increased temperature (850?C). The exothermic peak during the TG/DTA tests centered at 600?C is most likely associated with both the enthalpy change of transformation from the amorphous phase into crystalline zirconia and the oxidation of Pd phase in HTM cermet in air. The endothermic peak centered at 800?C is associated with the dissociation of PdO to Pd for the HTM cermet sample in both inert N2 environment and air. There is a corresponding weight gain as oxidation occurs for palladium (Pd) phase to form palladium oxide (PdO) and there is a weight loss as the unstable PdO is dissociated back to Pd and

  19. Upgradation of bauxite by molecular hydrogen and hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Parhi, B. R.; Sahoo, S. K.; Mishra, S. C.; Bhoi, B.; Paramguru, R. K.; Satapathy, B. K.

    2016-10-01

    An approach was developed to upgrade the bauxite ore by molecular hydrogen and hydrogen plasma. A gibbsite-type bauxite sample was obtained from National Aluminium Company (NALCO), Odisha, India. The obtained sample was crushed and sieved (to 100 μm) prior to the chemical analysis and grain-size distribution study. The bauxite sample was calcined in the temperature range from 500 to 700°C for different time intervals to optimize the conditions for maximum moisture removal. This process was followed by the reduction of the calcined ore by molecular hydrogen and hydrogen plasma. Extraction of alumina from the reduced ore was carried out via acid leaching in chloride media for 2 h at 60°C. X-ray diffraction, scanning electron microscopy, thermogravimetry in conjunction with differential scanning calorimetry, and Fourier transform infrared spectroscopy were used to determine the physicochemical characteristics of the material before and after extraction. Alumina extracted from the reduced ore at the optimum calcination temperature of 700°C and the optimum calcination time of 4 h is found to be 90% pure.

  20. Dense Plasma Focus - From Alternative Fusion Source to Versatile High Energy Density Plasma Source for Plasma Nanotechnology

    NASA Astrophysics Data System (ADS)

    Rawat, R. S.

    2015-03-01

    The dense plasma focus (DPF), a coaxial plasma gun, utilizes pulsed high current electrical discharge to heat and compress the plasma to very high density and temperature with energy densities in the range of 1-10 × 1010 J/m3. The DPF device has always been in the company of several alternative magnetic fusion devices as it produces intense fusion neutrons. Several experiments conducted on many different DPF devices ranging over several order of storage energy have demonstrated that at higher storage energy the neutron production does not follow I4 scaling laws and deteriorate significantly raising concern about the device's capability and relevance for fusion energy. On the other hand, the high energy density pinch plasma in DPF device makes it a multiple radiation source of ions, electron, soft and hard x-rays, and neutrons, making it useful for several applications in many different fields such as lithography, radiography, imaging, activation analysis, radioisotopes production etc. Being a source of hot dense plasma, strong shockwave, intense energetic beams and radiation, etc, the DPF device, additionally, shows tremendous potential for applications in plasma nanoscience and plasma nanotechnology. In the present paper, the key features of plasma focus device are critically discussed to understand the novelties and opportunities that this device offers in processing and synthesis of nanophase materials using, both, the top-down and bottom-up approach. The results of recent key experimental investigations performed on (i) the processing and modification of bulk target substrates for phase change, surface reconstruction and nanostructurization, (ii) the nanostructurization of PLD grown magnetic thin films, and (iii) direct synthesis of nanostructured (nanowire, nanosheets and nanoflowers) materials using anode target material ablation, ablated plasma and background reactive gas based synthesis and purely gas phase synthesis of various different types of

  1. Properties of hot dense plasmas by Orbital-Free Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Clerouin, Jean

    2011-10-01

    During the last decade DFT calculations have been successfully applied to the WDM regime. To overcome the limitations of DFT in temperature and density we propose to return to the very basis of DFT by using an ``only on the density'' formulation of the electronic kinetic energy, essentially captured by the finite temperature formulation of the Thomas-Fermi theory. High temperatures (up to few KeV) and high densities (up to 10 ×ρ0) systems can be addressed by orbital free molecular dynamics simulations (OFMD) at the expense of a fine description of atomic properties such as binding properties. Thanks to an efficient numerical scheme, up to thousands of particles can be propagated giving accurate static and dynamical properties without any assumptions on the ionization state or on the screening of interactions. Simulations of hydrogen and iron up to 5 keV and boron up to 10 times the normal density were performed. Very dissymmetrical mixtures can be also treated without difficulties. More recently, this method has been applied to hydrogen at high density (up to 160 g/cc) and high temperature (up to 1 KeV) to generate long trajectories for a later computation of the thermal conductivity with classical DFT. This method bridges the gap between quantum and classical molecular dynamics in the field of hot-dense plasmas and could be also used as a platform to include more physics such as nuclear reactions or interaction with a radiative field.

  2. Electron-ion collision-frequency for x-ray Thomson scattering in dense plasmas

    SciTech Connect

    Faussurier, Gérald Blancard, Christophe

    2016-01-15

    Two methods are presented to calculate the electron-ion collision-frequency in dense plasmas using an average-atom model. The first one is based on the Kubo-Greenwood approach. The second one uses the Born and Lenard-Balescu approximations. The two methods are used to calculate x-ray Thomson scattering spectra. Illustrations are shown for dense beryllium and aluminum plasmas. Comparisons with experiment are presented in the case of an x-ray Thomson scattering spectrum.

  3. Electron-ion collision-frequency for x-ray Thomson scattering in dense plasmas

    NASA Astrophysics Data System (ADS)

    Faussurier, Gérald; Blancard, Christophe

    2016-01-01

    Two methods are presented to calculate the electron-ion collision-frequency in dense plasmas using an average-atom model. The first one is based on the Kubo-Greenwood approach. The second one uses the Born and Lenard-Balescu approximations. The two methods are used to calculate x-ray Thomson scattering spectra. Illustrations are shown for dense beryllium and aluminum plasmas. Comparisons with experiment are presented in the case of an x-ray Thomson scattering spectrum.

  4. Phonon Localization by Mass Disorder in Dense Hydrogen-Deuterium Binary Alloy

    NASA Astrophysics Data System (ADS)

    Howie, Ross T.; Magdǎu, Ioan B.; Goncharov, Alexander F.; Ackland, Graeme J.; Gregoryanz, Eugene

    2014-10-01

    Using a combination of the Raman spectroscopy and density functional theory calculations on dense hydrogen-deuterium mixtures of various concentrations, we demonstrate that, at 300 K and above 200 GPa, they transform into phase IV, forming a disordered binary alloy with six highly localized intramolecular vibrational (vibrons) and four delocalized low-frequency (<1200 cm-1) modes. Hydrogen-deuterium mixtures are unique in showing a purely mass-induced localization effect in the quantum solid: chemical bonding is isotope-independent while the mass varies by a factor of 2.

  5. Charge exchange and ionization cross sections of H{sup +}+H collision in dense quantum plasmas

    SciTech Connect

    Zhang, Ling-yu; Qi, Xin; Zhao, Xiao-ying; Meng, Dong-yuan; Xiao, Guo-qing; Duan, Wen-shan; Yang, Lei

    2013-11-15

    The plasma screening effects of dense quantum plasmas on H{sup +}+H charge exchange and ionization cross sections are calculated by the classical trajectory Monte Carlo method. For charge exchange cross sections, it is found that the screening effects reduce cross sections slightly in weak screening conditions. However, cross sections are reduced substantially in strong screening conditions. For ionization cross sections, with the increase of screening effects, cross sections for low energies increase more rapidly than those for high energies. When the screening effects are strong enough, it is found that ionization cross sections decrease with the increase of incident H{sup +} energy. In addition, the cross sections have been compared with those in weakly coupled plasmas. It is found that in weak screening conditions, plasma screening effects in the two plasmas are approximately the same, while in strong screening conditions, screening effects of dense quantum plasmas are stronger than those of weakly coupled plasmas.

  6. Producing Hydrogen by Plasma Pyrolysis of Methane

    NASA Technical Reports Server (NTRS)

    Atwater, James; Akse, James; Wheeler, Richard

    2010-01-01

    Plasma pyrolysis of methane has been investigated for utility as a process for producing hydrogen. This process was conceived as a means of recovering hydrogen from methane produced as a byproduct of operation of a life-support system aboard a spacecraft. On Earth, this process, when fully developed, could be a means of producing hydrogen (for use as a fuel) from methane in natural gas. The most closely related prior competing process - catalytic pyrolysis of methane - has several disadvantages: a) The reactor used in the process is highly susceptible to fouling and deactivation of the catalyst by carbon deposits, necessitating frequent regeneration or replacement of the catalyst. b) The reactor is highly susceptible to plugging by deposition of carbon within fixed beds, with consequent channeling of flow, high pressure drops, and severe limitations on mass transfer, all contributing to reductions in reactor efficiency. c) Reaction rates are intrinsically low. d) The energy demand of the process is high.

  7. Kubo–Greenwood approach to conductivity in dense plasmas with average atom models

    SciTech Connect

    Starrett, C. E.

    2016-04-13

    In this study, a new formulation of the Kubo–Greenwood conductivity for average atom models is given. The new formulation improves upon previous treatments by explicitly including the ionic-structure factor. Calculations based on this new expression lead to much improved agreement with ab initio results for DC conductivity of warm dense hydrogen and beryllium, and for thermal conductivity of hydrogen. We also give and test a slightly modified Ziman–Evans formula for the resistivity that includes a non-free electron density of states, thus removing an ambiguity in the original Ziman–Evans formula. Again, results based on this expression are in good agreement with ab initio simulations for warm dense beryllium and hydrogen. However, for both these expressions, calculations of the electrical conductivity of warm dense aluminum lead to poor agreement at low temperatures compared to ab initio simulations.

  8. Kubo–Greenwood approach to conductivity in dense plasmas with average atom models

    DOE PAGES

    Starrett, C. E.

    2016-04-13

    In this study, a new formulation of the Kubo–Greenwood conductivity for average atom models is given. The new formulation improves upon previous treatments by explicitly including the ionic-structure factor. Calculations based on this new expression lead to much improved agreement with ab initio results for DC conductivity of warm dense hydrogen and beryllium, and for thermal conductivity of hydrogen. We also give and test a slightly modified Ziman–Evans formula for the resistivity that includes a non-free electron density of states, thus removing an ambiguity in the original Ziman–Evans formula. Again, results based on this expression are in good agreement withmore » ab initio simulations for warm dense beryllium and hydrogen. However, for both these expressions, calculations of the electrical conductivity of warm dense aluminum lead to poor agreement at low temperatures compared to ab initio simulations.« less

  9. Collector optic cleaning by in-situ hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Elg, Daniel T.; Panici, Gianluca A.; Srivastava, Shailendra N.; Ruzic, D. N.

    2015-03-01

    Extreme ultraviolet (EUV) lithography sources produce EUV photons by means of a hot, dense, highly-ionized Sn plasma. This plasma expels high-energy Sn ions and neutrals, which deposit on the collector optic used to focus the EUV light. This Sn deposition lowers the reflectivity of the collector optic, necessitating downtime for collector cleaning and replacement. A method is being developed to clean the collector with an in-situ hydrogen plasma, which provides hydrogen radicals that etch the Sn by forming gaseous SnH4. This method has the potential to significantly reduce collector-related source downtime. EUV reflectivity restoration and Sn cleaning have been demonstrated on multilayer mirror samples attached to a Sn-coated 300mm-diameter steel dummy collector driven at 300W RF power with 500sccm H2 and a pressure of 260mTorr. Use of the in-situ cleaning method is also being studied at industriallyapplicable high pressure (1.3 Torr). Plasma creation across the dummy collector surface has been demonstrated at 1.3 Torr with 1000sccm H2 flow, and etch rates have been measured. Additionally, etching has been demonstrated at higher flow rates up to 3200sccm. A catalytic probe has been used to measure radical density at various pressures and flows. The results lend further credence to the hypothesis that Sn removal is limited not by radical creation but by the removal of SnH4 from the plasma. Additionally, further progress has been made in an attempt to model the physical processes behind Sn removal.

  10. Nonlocality of radiative transfer in continuous spectra and Bremsstrahlung radiation transport in hot dense plasmas

    SciTech Connect

    Ivanov, V. V.; Kukushkin, A. B.

    1997-05-05

    The importance of nonlocal effects in radiative transfer in continuous spectra is shown in numerical modelling of space profiles of plasma temperature and Bremsstrahlung total power losses in a layer of adiabatically compressed hot dense plasma, via comparing the results of the exact, integral equation formalism and widely used approach of radiation temperature diffusion with Rosseland mean diffusion coefficient.

  11. Stability Limits and Properties of Dense Nonneutral Plasmas

    SciTech Connect

    Pollock, R. E.

    2001-12-14

    Developed equipment consisted of a high magnetic field solenoid with supporting instrumentation for electron plasma confinement. The solenoid was designed and delivered in year 1. In year 2, it was mapped and the trap was created and commissioned. In parallel, an ongoing program of beam-plasma interaction studies was carried out with a lower field trap developed earlier. The trap was placed in the IUCF Coolor (an intermediate-energy electron-cooled storage ring) and the effects of the beam on the plasma were investigated, including energy and angular momentum transfer. Student projects carried out within the beam-plasma group also included development of a diagnostic with high spatial resolution, and preparation for extension of the beam-plasma interaction study to much lower beam energy. This became the principal group activity during the latter part of the project.

  12. Self-similar expansion of a warm dense plasma

    SciTech Connect

    Djebli, Mourad; Moslem, Waleed M.

    2013-07-15

    The properties of an expanding plasma composed of degenerate electron fluid and non-degenerate ions are studied. For our purposes, we use fluid equations for ions together with the electron momentum equation that include quantum forces (e.g., the quantum statistical pressure, forces due to the electron-exchange and electron correlations effects) and the quasi-neutrality condition. The governing equation is written in a tractable form by using a self-similar transformation. Numerical results for typical beryllium plasma parameters revealed that, during the expansion, the ion acoustic speed decreases for both isothermal and adiabatic ion pressure. When compared with classical hydrodynamic plasma expansion model, the electrons and ions are found to initially escape faster in vacuum creating thus an intense electric field that accelerates most of the particles into the vacuum ahead of the plasma expansion. The relevancy of the present model to beryllium plasma produced by a femto-second laser is highlighted.

  13. Generation of electromagnetic emission during the injection of dense supersonic plasma flows into arched magnetic field

    NASA Astrophysics Data System (ADS)

    Viktorov, Mikhail; Golubev, Sergey; Mansfeld, Dmitry; Vodopyanov, Alexander

    2016-04-01

    Interaction of dense supersonic plasma flows with an inhomogeneous arched magnetic field is one of the key problems in near-Earth and space plasma physics. It can influence on the energetic electron population formation in magnetosphere of the Earth, movement of plasma flows in magnetospheres of planets, energy release during magnetic reconnection, generation of electromagnetic radiation and particle precipitation during solar flares eruption. Laboratory study of this interaction is of big interest to determine the physical mechanisms of processes in space plasmas and their detailed investigation under reproducible conditions. In this work a new experimental approach is suggested to study interaction of supersonic (ion Mach number up to 2.7) dense (up to 1015 cm-3) plasma flows with inhomogeneous magnetic field (an arched magnetic trap with a field strength up to 3.3 T) which opens wide opportunities to model space plasma processes in laboratory conditions. Fully ionized plasma flows with density from 1013 cm-3 to 1015 cm-3 are created by plasma generator on the basis of pulsed vacuum arc discharge. Then plasma is injected in an arched open magnetic trap along or across magnetic field lines. The filling of the arched magnetic trap with dense plasma and further magnetic field lines break by dense plasma flow were experimentally demonstrated. The process of plasma deceleration during the injection of plasma flow across the magnetic field lines was experimentally demonstrated. Pulsed plasma microwave emission at the electron cyclotron frequency range was observed. It was shown that frequency spectrum of plasma emission is determined by position of deceleration region in the magnetic field of the magnetic arc, and is affected by plasma density. Frequency spectrum shifts to higher frequencies with increasing of arc current (plasma density) because the deceleration region of plasma flow moves into higher magnetic field. The observed emission can be related to the

  14. Operational Characteristics of a High Voltage Dense Plasma Focus.

    DTIC Science & Technology

    1985-11-01

    material from the inner surface of the outer electrode, hence, a cleaner plasma experiment is possible and the possibility of restrike is reduced. In...equilibrium plasma is balanced by the mag- netic pressure, pm’ at the surface . That is, pm= B 2/8w = Pth = nDkT. Also, from Ampere’s law, neglecting...The forming plasma sheath is in contact with the insulator--and its large surface area--until the sheath lifts off the insulator and begins its ,4

  15. Ultra-High Intensity Magnetic Field Generation in Dense Plasma

    SciTech Connect

    Fisch, Nathaniel J

    2014-01-08

    I. Grant Objective The main objective of this grant proposal was to explore the efficient generation of intense currents. Whereasthefficient generation of electric current in low-­energy-­density plasma has occupied the attention of the magnetic fusion community for several decades, scant attention has been paid to carrying over to high-­energy-­density plasma the ideas for steady-­state current drive developed for low-­energy-­density plasma, or, for that matter, to inventing new methodologies for generating electric current in high-­energy-­density plasma. What we proposed to do was to identify new mechanisms to accomplish current generation, and to assess the operation, physics, and engineering basis of new forms of current drive in regimes appropriate for new fusion concepts.

  16. X-ray scattering as a dense plasma diagnostic

    NASA Astrophysics Data System (ADS)

    Nardi, Eran; Zinamon, Zeev; Riley, David; Woolsey, Nigel C.

    1998-04-01

    We show here that x-ray scattering can be a useful and potentially powerful plasma diagnostic, much in the same way as in liquid metals. The model used in the calculations is briefly described. The basic atomic data used here are obtained from the average atom INFERNO model. Three different configurations were studied: an Al plasma at several eV and a density of 0.1 g/cm3, which could be produced by radiatively heating an Al foil; an ultradense Al plasma which could be realized using colliding shock waves; and femtosecond laser produced plasmas. In the latter case we show that the applicability of the x-ray scattering method for obtaining information on both electron and ion temperature can be used in order to evaluate the electron-ion relaxation time. It is also shown that small angle scattering provides an equation of state diagnostic.

  17. Generation of electromagnetic emission during the injection of dense supersonic plasma flows into arched magnetic field

    NASA Astrophysics Data System (ADS)

    Mansfeld, Dmitry; Golubev, Sergey; Viktorov, Mikhail; Vodopyanov, Alexander; Yushkov, George

    2015-11-01

    Interaction of dense supersonic plasma flows with an inhomogeneous arched magnetic field is one of the key problems in near-Earth and space plasma physics. In this work a new experimental approach is suggested to study interaction of supersonic (ion Mach number up to 2.7) dense (up to 1015cm-3) plasma flows with inhomogeneous magnetic field (an arched magnetic trap with a field strength up to 3.3 T) which opens wide opportunities to model space plasma processes in laboratory conditions. Fully ionized plasma flows with density from 1013cm-3 to 1015cm-3 are created by plasma generator on the basis of pulsed vacuum arc discharge and injected into open magnetic trap across magnetic field lines. The filling of the arched magnetic trap with plasma and further magnetic field lines break by dense plasma flow was accompanied by pulsed electromagnetic emission at electron cyclotron frequency range, which can generated by electrons in the place of intensive deceleration of plasma flow in magnetic field. Grant of Ministry of Education 14.Z50.31.0007.

  18. Properties of warm dense polystyrene plasmas along the principal Hugoniot

    NASA Astrophysics Data System (ADS)

    Hu, S. X.; Boehly, T. R.; Collins, L. A.

    2014-06-01

    Polystyrene (CH) is often chosen as the ablator material for inertial confinement fusion (ICF) targets. Its static, dynamical, and optical properties in warm, dense conditions (due to shock compression) are important for ICF designs. Using the first-principles quantum molecular dynamics (QMD) method, we have investigated the equation of state (EOS) and optical reflectivity of shock-compressed CH up to an unprecedentedly high pressure of 62 Mbar along the principal Hugoniot. The QMD results are compared with existing experimental measurements as well as the SESAME EOS model. Although the Hugoniot pressure and/or temperature from QMD calculations agrees with experiments and the SESAME EOS model at low pressures below 10 Mbar, we have identified for the first time a stiffer behavior of shocked CH at higher pressures (>10 Mbar). Such a stiffer behavior of warm, dense CH can affect the ablation pressure (shock strength), shock coalescence dynamics, and nonuniformity growth in ICF implosions. In addition, we corrected the mistake made in literature for calculating the reflectivity of shocked CH and obtained good agreements with experimental measurements, which should lend credence to future opacity calculations in a first-principles fashion.

  19. Properties of warm dense polystyrene plasmas along the principal Hugoniot.

    PubMed

    Hu, S X; Boehly, T R; Collins, L A

    2014-06-01

    Polystyrene (CH) is often chosen as the ablator material for inertial confinement fusion (ICF) targets. Its static, dynamical, and optical properties in warm, dense conditions (due to shock compression) are important for ICF designs. Using the first-principles quantum molecular dynamics (QMD) method, we have investigated the equation of state (EOS) and optical reflectivity of shock-compressed CH up to an unprecedentedly high pressure of 62 Mbar along the principal Hugoniot. The QMD results are compared with existing experimental measurements as well as the SESAME EOS model. Although the Hugoniot pressure and/or temperature from QMD calculations agrees with experiments and the SESAME EOS model at low pressures below 10 Mbar, we have identified for the first time a stiffer behavior of shocked CH at higher pressures (>10 Mbar). Such a stiffer behavior of warm, dense CH can affect the ablation pressure (shock strength), shock coalescence dynamics, and nonuniformity growth in ICF implosions. In addition, we corrected the mistake made in literature for calculating the reflectivity of shocked CH and obtained good agreements with experimental measurements, which should lend credence to future opacity calculations in a first-principles fashion.

  20. Free-free opacity in dense plasmas with an average atom model

    DOE PAGES

    Shaffer, Nathaniel R.; Ferris, Natalie G.; Colgan, James Patrick; ...

    2017-02-28

    A model for the free-free opacity of dense plasmas is presented. The model uses a previously developed average atom model, together with the Kubo-Greenwood model for optical conductivity. This, in turn, is used to calculate the opacity with the Kramers-Kronig dispersion relations. Furthermore, comparisons to other methods for dense deuterium results in excellent agreement with DFT-MD simulations, and reasonable agreement with a simple Yukawa screening model corrected to satisfy the conductivity sum rule.

  1. Extreme hydrogen plasma densities achieved in a linear plasma generator

    SciTech Connect

    Rooij, G. J. van; Veremiyenko, V. P.; Goedheer, W. J.; de Groot, B.; Kleyn, A. W.; Smeets, P. H. M.; Versloot, T. W.; Whyte, D. G.; Engeln, R.; Schram, D. C.; Cardozo, N. J. Lopes

    2007-03-19

    A magnetized hydrogen plasma beam was generated with a cascaded arc, expanding in a vacuum vessel at an axial magnetic field of up to 1.6 T. Its characteristics were measured at a distance of 4 cm from the nozzle: up to a 2 cm beam diameter, 7.5x10{sup 20} m{sup -3} electron density, {approx}2 eV electron and ion temperatures, and 3.5 km/s axial plasma velocity. This gives a 2.6x10{sup 24} H{sup +} m{sup -2} s{sup -1} peak ion flux density, which is unprecedented in linear plasma generators. The high efficiency of the source is obtained by the combined action of the magnetic field and an optimized nozzle geometry. This is interpreted as a cross-field return current that leads to power dissipation in the beam just outside the source.

  2. A generalized model of atomic processes in dense plasmas

    NASA Astrophysics Data System (ADS)

    Chung, Hyun-Kyung; Chen, M.; Ciricosta, O.; Vinko, S.; Wark, J.; Lee, R. W.

    2015-11-01

    A generalized model of atomic processes in plasmas, FLYCHK, has been developed over a decade to provide experimentalists fast and simple but reasonable predictions of atomic properties of plasmas. For a given plasma condition, it provides charge state distributions and spectroscopic properties, which have been extensively used for experimental design and data analysis and currently available through NIST web site. In recent years, highly transient and non-equilibrium plasmas have been created with X-ray free electron lasers (XFEL). As high intensity x-rays interact with matter, the inner-shell electrons are ionized and Auger electrons and photo electrons are generated. With time, electrons participate in the ionization processes and collisional ionization by these electrons dominates photoionization as electron density increases. To study highly complex XFEL produced plasmas, SCFLY, an extended version of FLYCHK code has been used. The code accepts the time-dependent history of x-ray energy and intensity to compute population distribution and ionization distribution self-consistently with electron temperature and density assuming an instantaneous equilibration. The model and its applications to XFEL experiments will be presented as well as its limitations.

  3. Mesons from Laser-Induced Processes in Ultra-Dense Hydrogen H(0)

    PubMed Central

    2017-01-01

    Large signals of charged light mesons are observed in the laser-induced particle flux from ultra-dense hydrogen H(0) layers. The mesons are formed in such layers on metal surfaces using < 200 mJ laser pulse-energy. The time variation of the signal to metal foil collectors and the magnetic deflection to a movable pin collector are now studied. Relativistic charged particles with velocity up to 500 MeV u-1 thus 0.75 c are observed. Characteristic decay time constants for meson decay are observed, for charged and neutral kaons and also for charged pions. Magnetic deflections agree with charged pions and kaons. Theoretical predictions of the decay chains from kaons to muons in the particle beam agree with the results. Muons are detected separately by standard scintillation detectors in laser-induced processes in ultra-dense hydrogen H(0) as published previously. The muons formed do not decay appreciably within the flight distances used here. Most of the laser-ejected particle flux with MeV energy is not deflected by the magnetic fields and is thus neutral, either being neutral kaons or the ultra-dense HN(0) precursor clusters. Photons give only a minor part of the detected signals. PACS: 67.63.Gh, 14.40.-n, 79.20.Ds, 52.57.-z. PMID:28081199

  4. Mesons from Laser-Induced Processes in Ultra-Dense Hydrogen H(0).

    PubMed

    Holmlid, Leif

    2017-01-01

    Large signals of charged light mesons are observed in the laser-induced particle flux from ultra-dense hydrogen H(0) layers. The mesons are formed in such layers on metal surfaces using < 200 mJ laser pulse-energy. The time variation of the signal to metal foil collectors and the magnetic deflection to a movable pin collector are now studied. Relativistic charged particles with velocity up to 500 MeV u-1 thus 0.75 c are observed. Characteristic decay time constants for meson decay are observed, for charged and neutral kaons and also for charged pions. Magnetic deflections agree with charged pions and kaons. Theoretical predictions of the decay chains from kaons to muons in the particle beam agree with the results. Muons are detected separately by standard scintillation detectors in laser-induced processes in ultra-dense hydrogen H(0) as published previously. The muons formed do not decay appreciably within the flight distances used here. Most of the laser-ejected particle flux with MeV energy is not deflected by the magnetic fields and is thus neutral, either being neutral kaons or the ultra-dense HN(0) precursor clusters. Photons give only a minor part of the detected signals. PACS: 67.63.Gh, 14.40.-n, 79.20.Ds, 52.57.-z.

  5. Hydrogen Sulfide Inhibits Plasma Renin Activity

    PubMed Central

    Lu, Ming; Liu, Yi-Hong; Goh, Hong Swen; Wang, Josh Jia Xing; Yong, Qian-Chen; Wang, Rui

    2010-01-01

    The development of renovascular hypertension depends on the release of renin from the juxtaglomerular (JG) cells, a process regulated by intracellular cAMP. Hydrogen sulfide (H2S) downregulates cAMP production in some cell types by inhibiting adenylyl cyclase, suggesting the possibility that it may modulate renin release. Here, we investigated the effect of H2S on plasma renin activity and BP in rat models of renovascular hypertension. In the two-kidney-one-clip (2K1C) model of renovascular hypertension, the H2S donor NaHS prevented and treated hypertension. Compared with vehicle, NaHS significantly attenuated the elevation in plasma renin activity and angiotensin II levels but did not affect plasma angiotensin-converting enzyme activity. Furthermore, NaHS inhibited the upregulation of renin mRNA and protein levels in the clipped kidneys of 2K1C rats. In primary cultures of renin-rich kidney cells, NaHS markedly suppressed forskolin-stimulated renin activity in the medium and the intracellular increase in cAMP. In contrast, NaHS did not affect BP or plasma renin activity in normal or one-kidney-one-clip (1K1C) rats, both of which had normal plasma renin activity. In conclusion, these results demonstrate that H2S may inhibit renin activity by decreasing the synthesis and release of renin, suggesting its potential therapeutic value for renovascular hypertension. PMID:20360313

  6. Quantum-Mechanical Calculation of Ionization-Potential Lowering in Dense Plasmas

    NASA Astrophysics Data System (ADS)

    Son, Sang-Kil; Thiele, Robert; Jurek, Zoltan; Ziaja, Beata; Santra, Robin

    2014-07-01

    The charged environment within a dense plasma leads to the phenomenon of ionization-potential depression (IPD) for ions embedded in the plasma. Accurate predictions of the IPD effect are of crucial importance for modeling atomic processes occurring within dense plasmas. Several theoretical models have been developed to describe the IPD effect, with frequently discrepant predictions. Only recently, first experiments on IPD in Al plasma have been performed with an x-ray free-electron laser, where their results were found to be in disagreement with the widely used IPD model by Stewart and Pyatt. Another experiment on Al, at the Orion laser, showed disagreement with the model by Ecker and Kröll. This controversy shows a strong need for a rigorous and consistent theoretical approach to calculate the IPD effect. Here, we propose such an approach: a two-step Hartree-Fock-Slater model. With this parameter-free model, we can accurately and efficiently describe the experimental Al data and validate the accuracy of standard IPD models. Our model can be a useful tool for calculating atomic properties within dense plasmas with wide-ranging applications to studies on warm dense matter, shock experiments, planetary science, inertial confinement fusion, and nonequilibrium plasmas created with x-ray free-electron lasers.

  7. Arbitrary amplitude electrostatic wave propagation in a magnetized dense plasma containing helium ions and degenerate electrons

    NASA Astrophysics Data System (ADS)

    Mahmood, S.; Sadiq, Safeer; Haque, Q.; Ali, Munazza Z.

    2016-06-01

    The obliquely propagating arbitrary amplitude electrostatic wave is studied in a dense magnetized plasma having singly and doubly charged helium ions with nonrelativistic and ultrarelativistic degenerate electrons pressures. The Fermi temperature for ultrarelativistic degenerate electrons described by N. M. Vernet [(Cambridge University Press, Cambridge, 2007), p. 57] is used to define ion acoustic speed in ultra-dense plasmas. The pseudo-potential approach is used to solve the fully nonlinear set of dynamic equations for obliquely propagating electrostatic waves in a dense magnetized plasma containing helium ions. The upper and lower Mach number ranges for the existence of electrostatic solitons are found which depends on the obliqueness of the wave propagation with respect to applied magnetic field and charge number of the helium ions. It is found that only compressive (hump) soliton structures are formed in all the cases and only subsonic solitons are formed for a singly charged helium ions plasma case with nonrelativistic degenerate electrons. Both subsonic and supersonic soliton hump structures are formed for doubly charged helium ions with nonrelativistic degenerate electrons and ultrarelativistic degenerate electrons plasma case containing singly as well as doubly charged helium ions. The effect of propagation direction on the soliton amplitude and width of the electrostatic waves is also presented. The numerical plots are also shown for illustration using dense plasma parameters of a compact star (white dwarf) from literature.

  8. A Seemingly Simple Task: Filling a Solenoid Volume in Vacuum with Dense Plasma

    SciTech Connect

    Anders, Andre; Kauffeldt, Marina; Roy, Prabir; Oks, Efim

    2010-06-24

    Space-charge neutralization of a pulsed, high-current ion beam is required to compress and focus the beam on a target for warm dense matter physics or heavy ion fusion experiments. We described attempts to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary charge-compensating electrons. Among the options are plasma injection from four pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means and by an array of movable Langmuir probes. The plasma is produced at several cathode spots distributed azimuthally on the ring cathode. Beam neutralization and compression are accomplished, though issues of density, uniformity, and pulse-to-pulse reproducibly remain to be solved.

  9. Preionization Techniques in a kJ-Scale Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Povilus, Alexander; Shaw, Brian; Chapman, Steve; Podpaly, Yuri; Cooper, Christopher; Falabella, Steve; Prasad, Rahul; Schmidt, Andrea

    2016-10-01

    A dense plasma focus (DPF) is a type of z-pinch device that uses a high current, coaxial plasma gun with an implosion phase to generate dense plasmas. These devices can accelerate a beam of ions to MeV-scale energies through strong electric fields generated by instabilities during the implosion of the plasma sheath. The formation of these instabilities, however, relies strongly on the history of the plasma sheath in the device, including the evolution of the gas breakdown in the device. In an effort to reduce variability in the performance of the device, we attempt to control the initial gas breakdown in the device by seeding the system with free charges before the main power pulse arrives. We report on the effectiveness of two techniques developed for a kJ-scale DPF at LLNL, a miniature primer spark gap and pulsed, 255nm LED illumination. Prepared by LLNL under Contract DE-AC52-07NA27344.

  10. One method of producing a high-temperature dense plasma

    NASA Astrophysics Data System (ADS)

    Ternovoi, V. Ya.; Khishchenko, K. V.; Charakhch'yan, A. A.

    2009-05-01

    This paper considers the interaction between an absolutely rigid wall or a steel plate and the rarefaction wave arising in solid deuterium when a 30-150 GPa shock wave arrives at the free surface. It is shown that, in the entropy trace near the wall or interface with the plate, a high-temperature plasma arises, in which a thermonuclear fusion is possible, at least, for shock-wave pressures above 70 GPa. The dimension of the plasma region and the time of its establishment are proportional to the distance between the free surface and the wall. Estimates of the proportionality coefficients are given. It is noted that, in this case, unlike in other methods of high-temperature plasma generation, the time of existence of the plasma may not depend on the sound velocity in it. It is shown that, by using a conical solid-state target wit an exit hole, the shock-wave pressure in solid deuterium can be increased from 10 to 100 GPa.

  11. Dense Monoenergetic Proton Beams from Chirped Laser-Plasma Interaction

    NASA Astrophysics Data System (ADS)

    Galow, Benjamin J.; Salamin, Yousef I.; Liseykina, Tatyana V.; Harman, Zoltán; Keitel, Christoph H.

    2011-10-01

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultraintense (107 particles per bunch) and phase-space collimated beams of protons (energy spread of about 1%) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 1021W/cm2.

  12. Thermal conduction by electrons in hot dense plasmas

    SciTech Connect

    Khalfaoui, A.H.; Bennaceur, D.

    1997-03-01

    Based on a quantum collective approach, electron conduction opacity is analyzed, taking into account several nonideality effects such as electron-electron (e-e) collisions in addition to electron-ion collisions, dynamic shielding, electron partial degeneracy, and ion coupling. The collision process is based on electron wave functions interacting with the continuum oscillations (plasma waves). The e-e collisions, the main nonideal effect, contribute to the thermal conductivity calculation in the intermediate coupling regime. Hence, the extensively used Lorentz gas approximation cannot be justified for plasma of astrophysical interest. The present results are compared to existing theories of electron conduction in stellar matter. {copyright} {ital 1997} {ital The American Astronomical Society}

  13. X-ray emission of exotic ions in dense plasmas

    NASA Astrophysics Data System (ADS)

    Rosmej, F. B.; Khaghani, D.; Dozières, M.; Dachicourt, R.; Šmíd, M.; Renner, O.

    2017-03-01

    Hollow ion X-ray emission has been observed in experiments studying interaction of heavy ion beams with solids and their occurrence has been ascribed to charge exchange processes occurring when highly charged ions interact with a metal surface. In high temperature high-density plasmas, like, e.g., high intensity laser produced plasmas or high current Z-pinches, numerous researchers have reported about "exotic" X-ray transitions of hollow ions: K0LX →K1LX-1+hνhollow. Although atomic structure calculations seem to confirm that measured line positions correspond to transitions in hollow ions, line identification is difficult and the observed high intensity remains a mystery (by orders of magnitude) up to present days.

  14. Hydrogen atom in a laser-plasma

    NASA Astrophysics Data System (ADS)

    Falaye, Babatunde J.; Sun, Guo-Hua; Liman, Muhammed S.; Oyewumi, K. J.; Dong, Shi-Hai

    2016-11-01

    We scrutinize the behaviour of the eigenvalues of a hydrogen atom in a quantum plasma as it interacts with an electric field directed along θ  =  π and is exposed to linearly polarized intense laser field radiation. We refer to the interaction of the plasma with the laser light as laser-plasma. Using the Kramers-Henneberger (KH) unitary transformation, which is the semiclassical counterpart of the Block-Nordsieck transformation in the quantized field formalism, the squared vector potential that appears in the equation of motion is eliminated and the resultant equation is expressed in the KH frame. Within this frame, the resulting potential and the corresponding wavefunction have been expanded in Fourier series, and using Ehlotzky’s approximation we obtain a laser-dressed potential to simulate an intense laser field. By fitting the exponential-cosine-screened Coulomb potential into the laser-dressed potential, and then expanding it in Taylor series up to O≤ft({{r}4},α 09\\right) , we obtain the eigensolution (eigenvalues and wavefunction) of the hydrogen atom in laser-plasma encircled by an electric field, within the framework of perturbation theory formalism. Our numerical results show that for a weak external electric field and a very large Debye screening parameter length, the system is strongly repulsive, in contrast with the case for a strong external electric field and a small Debye screening parameter length, when the system is very attractive. This work has potential applications in the areas of atomic and molecular processes in external fields, including interactions with strong fields and short pulses.

  15. Restrike Particle Beam Experiments on a Dense Plasma Focus.

    DTIC Science & Technology

    1980-11-30

    soft Xray spectrometer should enable the formation of a fairly complete picture of the plasma phenomena as well as that of the beams for input into the...SSNTD are insensitive to light, electrons or Xrays 2) Record is virtually permanent 3) Direct measurement of fast particles is possible and (detection...detectors. The bands are delimited by Ross balanced filtering technique. This technique uses the fact that the stopping power for xrays has 3narp edges at

  16. Energy Flow in Dense Off-Equilibrium Plasma

    DTIC Science & Technology

    2016-07-15

    and kT0 is the product of Boltzmann’s constant with the ambient temperature . We measured the R0 via backlighting with sound off to be 22 2 m which...pulsate by an externally imposed sound wave. Adiabatic compression, and in some cases shock waves, heat the gas during the collapse phase. At...spectral analysis of the emitted light which gives the temperature , and iii) light scattering which is sensitive to the plasma density. The clock-like

  17. Dense monoenergetic proton beams from chirped laser-plasma interaction.

    PubMed

    Galow, Benjamin J; Salamin, Yousef I; Liseykina, Tatyana V; Harman, Zoltán; Keitel, Christoph H

    2011-10-28

    Interaction of a frequency-chirped laser pulse with single protons and a hydrogen gas target is studied analytically and by means of particle-in-cell simulations, respectively. The feasibility of generating ultraintense (10(7) particles per bunch) and phase-space collimated beams of protons (energy spread of about 1%) is demonstrated. Phase synchronization of the protons and the laser field, guaranteed by the appropriate chirping of the laser pulse, allows the particles to gain sufficient kinetic energy (around 250 MeV) required for such applications as hadron cancer therapy, from state-of-the-art laser systems of intensities of the order of 10(21) W/cm(2).

  18. Spectrally Resolved Intensities of Ultra-Dense Hot Aluminum Plasmas

    SciTech Connect

    Gil, J. M.; Rodriguez, R.; Florido, R.; Rubiano, J. G.; Martel, P.; Minguez, E.; Sauvan, P.; Angelo, P.; Dalimier, E.; Schott, R.; Mancini, R.

    2008-10-22

    We present a first study of spectroscopic determination of electron temperature and density spatial profiles of aluminum K-shell line emission spectra from laser-shocked aluminum experiments performed at LULI. The radiation emitted by the aluminum plasma was dispersed with an ultra-high resolution spectrograph ({lambda}/{delta}{lambda}{approx_equal}6000). From the recorded films one can extract a set of time-integrated emission lineouts associated with the corresponding spatial region of the plasma. The observed spectra include the Ly{alpha}, He{beta}, He{gamma}, Ly{beta} and Ly{gamma} line emissions and their associated He- and Li-like satellites thus covering a photon energy range from 1700 eV to 2400 eV approximately. The data analysis rely on the ABAKO/RAPCAL computational package, which has been recently developed at the University of Las Palmas de Gran Canaria and takes into account non-equilibrium collisional-radiative atomic kinetics, Stark broadened line shapes and radiation transport calculations.

  19. Fast electron heating of dense plasma relevant to shock ignition

    NASA Astrophysics Data System (ADS)

    Fox, T. E.; Robinson, A. P. L.; Pasley, J.

    2013-10-01

    With an intensity in the range of 1016 W/cm2, the ignitor pulse in shock-ignition inertial confinement fusion is well above the threshold of parametric instabilities. Simulations (e.g. Klimo et al. 2011 Phys. Plasmas 18, 082709) indicate that a significant amount of energy will be deposited in energetic electrons with energies <100 keV and it has been proposed that these may play a beneficial role in enhancing the ignitor shock. Simulations by Gus'kov et al. (Phys. Rev. Lett. 109, 255004 (2012)) show that, under shock-ignition relevant conditions, a mono-energetic electron beam can drive strong shocks in a uniform plasma. We extend this study to the more realistic case of a Maxwellian energy distribution in the fast electron population. Having a distribution of electron mean-free-paths results in a more extended heating profile compared to a mono-energetic beam. However, we show it is still possible to launch strong shocks in this more realistic scenario and achieve equivalent pressures. The peak pressures achieved compare well with analytic scalings. We thank AWE for their financial assistance in support of the doctoral research of T. E. F.

  20. X-ray Spectroscopy of Hot Dense Plasmas: Experimental Limits, Line Shifts and Field Effects

    SciTech Connect

    Renner, Oldrich; Sauvan, Patrick; Dalimier, Elisabeth; Riconda, Caterina; Rosmej, Frank B.; Weber, Stefan; Nicolai, Philippe; Peyrusse, Olivier; Uschmann, Ingo; Hoefer, Sebastian; Kaempfer, Tino; Loetzsch, Robert; Zastrau, Ulf; Foerster, Eckhart; Oks, Eugene

    2008-10-22

    High-resolution x-ray spectroscopy is capable of providing complex information on environmental conditions in hot dense plasmas. Benefiting from application of modern spectroscopic methods, we report experiments aiming at identification of different phenomena occurring in laser-produced plasma. Fine features observed in broadened profiles of the emitted x-ray lines and their satellites are interpreted using theoretical models predicting spectra modification under diverse experimental situations.

  1. Plasma processing methods for hydrogen production

    NASA Astrophysics Data System (ADS)

    Mizeraczyk, Jerzy; Jasiński, Mariusz

    2016-08-01

    In the future a transfer from the fossil fuel-based economy to hydrogen-based economy is expected. Therefore the development of systems for efficient H2 production becomes important. The several conventional methods of mass-scale (or central) H2 production (methane, natural gas and higher hydrocarbons reforming, coal gasification reforming) are well developed and their costs of H2 production are acceptable. However, due to the H2 transport and storage problems the small-scale (distributed) technologies for H2 production are demanded. However, these new technologies have to meet the requirement of producing H2 at a production cost of (1-2)/kg(H2) (or 60 g(H2)/kWh) by 2020 (the U.S. Department of Energy's target). Recently several plasma methods have been proposed for the small-scale H2 production. The most promising plasmas for this purpose seems to be those generated by gliding, plasmatron and nozzle arcs, and microwave discharges. In this paper plasma methods proposed for H2 production are briefly described and critically evaluated from the view point of H2 production efficiency. The paper is aiming at answering a question if any plasma method for the small-scale H2 production approaches such challenges as the production energy yield of 60 g(H2)/kWh, high production rate, high reliability and low investment cost. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  2. Transport properties of dense deuterium-tritium plasmas.

    PubMed

    Wang, Cong; Long, Yao; He, Xian-Tu; Wu, Jun-Feng; Ye, Wen-Hua; Zhang, Ping

    2013-07-01

    Consistent descriptions of the equation of states and information about the transport coefficients of the deuterium-tritium mixture are demonstrated through quantum molecular dynamic (QMD) simulations (up to a density of 600 g/cm(3) and a temperature of 10(4) eV). Diffusion coefficients and viscosity are compared to the one-component plasma model in different regimes from the strong coupled to the kinetic one. Electronic and radiative transport coefficients, which are compared to models currently used in hydrodynamic simulations of inertial confinement fusion, are evaluated up to 800 eV. The Lorentz number is discussed from the highly degenerate to the intermediate region. One-dimensional hydrodynamic simulation results indicate that different temperature and density distributions are observed during the target implosion process by using the Spitzer model and ab initio transport coefficients.

  3. Numerical analysis of thermonuclear detonation in dense plasma

    NASA Astrophysics Data System (ADS)

    Avronin, Y. N.; Bunatyan, A. A.; Gadzhiyev, A. D.; Mustafin, K. A.; Nurbakov, A. S.; Pisarev, V. N.; Feoktistov, L. P.; Frolov, V. D.; Shibarshov, L. I.

    1985-01-01

    The propagation of thermonuclear combustion from the region heated to thermonuclear temperatures by an external source to the remaining part of the target was investigated. The target was a tube of inert material (gold, lead, beryllium, etc.) filled with a deuterium-tritium mixture. It was determined analytically that thermonuclear combustion can propagate from a small portion of a nonspherical target to the remainder of the target and that a steady-state thermonuclear detonation wave can be formed. The role of various physical processes in thermonuclear detonation was investigated. Shock wave is the main mechanism underlying detonation propagation. The detonation rate and intensity of the thermonuclear reaction is influenced by the leakage of heat due to transvere heat conductivity. The critical diameter for thermonuclear detonation was determined approximately for a plasma filament encased in a housing with twice the density of the fuel.

  4. Quantum molecular dynamics simulations of transport properties in liquid and dense-plasma plutonium.

    PubMed

    Kress, J D; Cohen, James S; Kilcrease, D P; Horner, D A; Collins, L A

    2011-02-01

    We have calculated the viscosity and self-diffusion coefficients of plutonium in the liquid phase using quantum molecular dynamics (QMD) and in the dense-plasma phase using orbital-free molecular dynamics (OFMD), as well as in the intermediate warm dense matter regime with both methods. Our liquid metal results for viscosity are about 40% lower than measured experimentally, whereas a previous calculation using an empirical interatomic potential (modified embedded-atom method) obtained results 3-4 times larger than the experiment. The QMD and OFMD results agree well at the intermediate temperatures. The calculations in the dense-plasma regime for temperatures from 50 to 5000 eV and densities about 1-5 times ambient are compared with the one-component plasma (OCP) model, using effective charges given by the average-atom code INFERNO. The INFERNO-OCP model results agree with the OFMD to within about a factor of 2, except for the viscosity at temperatures less than about 100 eV, where the disagreement is greater. A Stokes-Einstein relationship of the viscosities and diffusion coefficients is found to hold fairly well separately in both the liquid and dense-plasma regimes.

  5. A nonlinear model for magnetoacoustic waves in dense dissipative plasmas with degenerate electrons

    SciTech Connect

    Masood, W.; Jahangir, R.; Siddiq, M.; Eliasson, B.

    2014-10-15

    The properties of nonlinear fast magnetoacoustic waves in dense dissipative plasmas with degenerate electrons are studied theoretically in the framework of the Zabolotskaya-Khokhlov (ZK) equation for small but finite amplitude excitations. Shock-like solutions of the ZK equation are obtained and are applied to parameters relevant to white dwarf stars.

  6. Quantum molecular dynamics simulations of transport properties in liquid and dense-plasma plutonium

    NASA Astrophysics Data System (ADS)

    Kress, J. D.; Cohen, James S.; Kilcrease, D. P.; Horner, D. A.; Collins, L. A.

    2011-02-01

    We have calculated the viscosity and self-diffusion coefficients of plutonium in the liquid phase using quantum molecular dynamics (QMD) and in the dense-plasma phase using orbital-free molecular dynamics (OFMD), as well as in the intermediate warm dense matter regime with both methods. Our liquid metal results for viscosity are about 40% lower than measured experimentally, whereas a previous calculation using an empirical interatomic potential (modified embedded-atom method) obtained results 3-4 times larger than the experiment. The QMD and OFMD results agree well at the intermediate temperatures. The calculations in the dense-plasma regime for temperatures from 50 to 5000 eV and densities about 1-5 times ambient are compared with the one-component plasma (OCP) model, using effective charges given by the average-atom code inferno. The inferno-OCP model results agree with the OFMD to within about a factor of 2, except for the viscosity at temperatures less than about 100 eV, where the disagreement is greater. A Stokes-Einstein relationship of the viscosities and diffusion coefficients is found to hold fairly well separately in both the liquid and dense-plasma regimes.

  7. Prediction of a Mobile Solid State in Dense Hydrogen under High Pressures.

    PubMed

    Geng, Hua Y; Wu, Q; Sun, Y

    2017-01-05

    Solid rigidity and liquid-scale mobility are thought to be incompatible in elemental substances. One cannot have an elemental solid that is long-range positionally ordered wherein the atoms flow like in a liquid simultaneously. The only exception might be the hypothetical supersolid state of (4)He. In this work, we demonstrate that such exotic state could exist even in the classical regime. Using ab initio molecular dynamics (AIMD) and ab initio path integral molecular dynamics (AI-PIMD), a novel state of dense hydrogen that simultaneously has both long-range spatial ordering and liquid-scale atomic mobility is discovered at 1 to 1.5 TPa (1 TPa ≈ 10 000 000 atmospheric pressures). The features distinct from a normal solid and liquid are carefully characterized, and the stability and melting behavior are investigated. Extensive AI-PIMD simulations further revealed that this state might be (meta-)stable even at ultralow temperatures, suggesting an emerging candidate for an alternative type of supersolid state in dense metallic hydrogen.

  8. Particle-in-cell simulations of laser beat-wave magnetization of dense plasmas

    SciTech Connect

    Welch, D. R.; Genoni, T. C.; Thoma, C.; Rose, D. V.; Hsu, S. C.

    2014-03-15

    The interaction of two lasers with a difference frequency near that of the ambient plasma frequency produces beat waves that can resonantly accelerate thermal electrons. These beat waves can be used to drive electron current and thereby embed magnetic fields into the plasma [Welch et al., Phys. Rev. Lett. 109, 225002 (2012)]. In this paper, we present two-dimensional particle-in-cell simulations of the beat-wave current-drive process over a wide range of angles between the injected lasers, laser intensities, and plasma densities. We discuss the application of this technique to the magnetization of dense plasmas, motivated in particular by the problem of forming high-β plasma targets in a standoff manner for magneto-inertial fusion. The feasibility of a near-term experiment embedding magnetic fields using lasers with micron-scale wavelengths into a ∼10{sup 18} cm{sup −3}-density plasma is assessed.

  9. Equation-of-state measurement of dense plasmas heated with fast protons.

    PubMed

    Dyer, G M; Bernstein, A C; Cho, B I; Osterholz, J; Grigsby, W; Dalton, A; Shepherd, R; Ping, Y; Chen, H; Widmann, K; Ditmire, T

    2008-07-04

    Using an ultrafast pulse of mega-electron-volt energy protons accelerated from a laser-irradiated foil, we have heated solid density aluminum plasmas to temperatures in excess of 15 eV. By measuring the temperature and the expansion rate of the heated Al plasma simultaneously and with picosecond time resolution we have found the predictions of the SESAME Livermore equation-of-state (LEOS) tables to be accurate to within 18%, in this dense plasma regime, where there have been few previous experimental measurements.

  10. Equation-of-State Measurement of Dense Plasmas Heated With Fast Protons

    SciTech Connect

    Dyer, G. M.; Bernstein, A. C.; Cho, B. I.; Osterholz, J.; Grigsby, W.; Dalton, A.; Ditmire, T.; Shepherd, R.; Ping, Y.; Chen, H.; Widmann, K.

    2008-07-04

    Using an ultrafast pulse of mega-electron-volt energy protons accelerated from a laser-irradiated foil, we have heated solid density aluminum plasmas to temperatures in excess of 15 eV. By measuring the temperature and the expansion rate of the heated Al plasma simultaneously and with picosecond time resolution we have found the predictions of the SESAME Livermore equation-of-state (LEOS) tables to be accurate to within 18%, in this dense plasma regime, where there have been few previous experimental measurements.

  11. Equation-of-State Measurement of Dense Plasmas Heated With Fast Protons

    NASA Astrophysics Data System (ADS)

    Dyer, G. M.; Bernstein, A. C.; Cho, B. I.; Osterholz, J.; Grigsby, W.; Dalton, A.; Shepherd, R.; Ping, Y.; Chen, H.; Widmann, K.; Ditmire, T.

    2008-07-01

    Using an ultrafast pulse of mega-electron-volt energy protons accelerated from a laser-irradiated foil, we have heated solid density aluminum plasmas to temperatures in excess of 15 eV. By measuring the temperature and the expansion rate of the heated Al plasma simultaneously and with picosecond time resolution we have found the predictions of the SESAME Livermore equation-of-state (LEOS) tables to be accurate to within 18%, in this dense plasma regime, where there have been few previous experimental measurements.

  12. GigaGauss solenoidal magnetic field inside bubbles excited in under-dense plasma

    NASA Astrophysics Data System (ADS)

    Lécz, Zs.; Konoplev, I. V.; Seryi, A.; Andreev, A.

    2016-10-01

    This paper proposes a novel and effective method for generating GigaGauss level, solenoidal quasi-static magnetic fields in under-dense plasma using screw-shaped high intensity laser pulses. This method produces large solenoidal fields that move with the driving laser pulse and are collinear with the accelerated electrons. This is in contrast with already known techniques which rely on interactions with over-dense or solid targets and generates radial or toroidal magnetic field localized at the stationary target. The solenoidal field is quasi-stationary in the reference frame of the laser pulse and can be used for guiding electron beams. It can also provide synchrotron radiation beam emittance cooling for laser-plasma accelerated electron and positron beams, opening up novel opportunities for designs of the light sources, free electron lasers, and high energy colliders based on laser plasma acceleration.

  13. Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

    NASA Astrophysics Data System (ADS)

    Booth, N.; Robinson, A. P. L.; Hakel, P.; Clarke, R. J.; Dance, R. J.; Doria, D.; Gizzi, L. A.; Gregori, G.; Koester, P.; Labate, L.; Levato, T.; Li, B.; Makita, M.; Mancini, R. C.; Pasley, J.; Rajeev, P. P.; Riley, D.; Wagenaars, E.; Waugh, J. N.; Woolsey, N. C.

    2015-11-01

    Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.

  14. Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

    PubMed Central

    Booth, N.; Robinson, A. P. L.; Hakel, P.; Clarke, R. J.; Dance, R. J.; Doria, D.; Gizzi, L. A.; Gregori, G.; Koester, P.; Labate, L.; Levato, T.; Li, B.; Makita, M.; Mancini, R. C.; Pasley, J.; Rajeev, P. P.; Riley, D.; Wagenaars, E.; Waugh, J. N.; Woolsey, N. C.

    2015-01-01

    Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs. PMID:26541650

  15. Ion acoustic solitons in dense magnetized plasmas with nonrelativistic and ultrarelativistic degenerate electrons and positrons

    SciTech Connect

    Sadiq, Safeer; Mahmood, S.; Haque, Q.; Ali, Munazza Zulfiqar

    2014-09-20

    The propagation of electrostatic waves in a dense magnetized electron-positron-ion (EPI) plasma with nonrelativistic and ultrarelativistic degenerate electrons and positrons is investigated. The linear dispersion relation is obtained for slow and fast electrostatic waves in the EPI plasma. The limiting cases for ion acoustic wave (slow) and ion cyclotron wave (fast) are also discussed. Using the reductive perturbation method, two-dimensional propagation of ion acoustic solitons is found for both the nonrelativistic and ultrarelativistic degenerate electrons and positrons. The effects of positron concentration, magnetic field, and mass of ions on ion acoustic solitons are shown in numerical plots. The proper form of Fermi temperature for nonrelativistic and ultrarelativistic degenerate electrons and positrons is employed, which has not been used in earlier published work. The present investigation is useful for the understanding of linear and nonlinear electrostatic wave propagation in the dense magnetized EPI plasma of compact stars. For illustration purposes, we have applied our results to a pulsar magnetosphere.

  16. GigaGauss solenoidal magnetic field inside bubbles excited in under-dense plasma

    PubMed Central

    Lécz, Zs.; Konoplev, I. V.; Seryi, A.; Andreev, A.

    2016-01-01

    This paper proposes a novel and effective method for generating GigaGauss level, solenoidal quasi-static magnetic fields in under-dense plasma using screw-shaped high intensity laser pulses. This method produces large solenoidal fields that move with the driving laser pulse and are collinear with the accelerated electrons. This is in contrast with already known techniques which rely on interactions with over-dense or solid targets and generates radial or toroidal magnetic field localized at the stationary target. The solenoidal field is quasi-stationary in the reference frame of the laser pulse and can be used for guiding electron beams. It can also provide synchrotron radiation beam emittance cooling for laser-plasma accelerated electron and positron beams, opening up novel opportunities for designs of the light sources, free electron lasers, and high energy colliders based on laser plasma acceleration. PMID:27796327

  17. Measurement of charged-particle stopping in warm-dense plasma

    DOE PAGES

    Zylstra, A.  B.; Frenje, J.  A.; Grabowski, P. E.; ...

    2015-05-27

    We measured the stopping of energetic protons in an isochorically-heated solid-density Be plasma with an electron temperature of ~32 eV, corresponding to moderately-coupled [(e²/a/(kBTe + EF ) ~ 0.3] and moderately-degenerate [kBTe/EF ~2] 'warm dense matter' (WDM) conditions. We present the first high-accuracy measurements of charged-particle energy loss through dense plasma, which shows an increased loss relative to cold matter, consistent with a reduced mean ionization potential. The data agree with stopping models based on an ad-hoc treatment of free and bound electrons, as well as the average-atom local-density approximation; this work is the first test of these theories inmore » WDM plasma.« less

  18. Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs.

    PubMed

    Booth, N; Robinson, A P L; Hakel, P; Clarke, R J; Dance, R J; Doria, D; Gizzi, L A; Gregori, G; Koester, P; Labate, L; Levato, T; Li, B; Makita, M; Mancini, R C; Pasley, J; Rajeev, P P; Riley, D; Wagenaars, E; Waugh, J N; Woolsey, N C

    2015-11-06

    Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.

  19. Measurement of charged-particle stopping in warm-dense plasma

    SciTech Connect

    Zylstra, A.  B.; Frenje, J.  A.; Grabowski, P. E.; Li, C.  K.; Collins, G.  W.; Fitzsimmons, P.; Glenzer, S.; Graziani, F.; Hansen, S.  B.; Hu, S. X.; Johnson, M. Gatu; Keiter, P.; Reynolds, H.; Rygg, J.  R.; Séguin, F. H.; Petrasso, R. D.

    2015-05-27

    We measured the stopping of energetic protons in an isochorically-heated solid-density Be plasma with an electron temperature of ~32 eV, corresponding to moderately-coupled [(e²/a/(kBTe + EF ) ~ 0.3] and moderately-degenerate [kBTe/EF ~2] 'warm dense matter' (WDM) conditions. We present the first high-accuracy measurements of charged-particle energy loss through dense plasma, which shows an increased loss relative to cold matter, consistent with a reduced mean ionization potential. The data agree with stopping models based on an ad-hoc treatment of free and bound electrons, as well as the average-atom local-density approximation; this work is the first test of these theories in WDM plasma.

  20. Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

    SciTech Connect

    Booth, N.; Robinson, A. P. L.; Hakel, P.; Clarke, R. J.; Dance, R. J.; Doria, D.; Gizzi, L. A.; Gregori, G.; Koester, P.; Labate, L.; Levato, T.; Li, B.; Makita, M.; Mancini, R. C.; Pasley, J.; Rajeev, P. P.; Riley, D.; Wagenaars, E.; Waugh, J. N.; Woolsey, N. C.

    2015-11-06

    Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. Furthermore, the inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.

  1. Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

    DOE PAGES

    Booth, N.; Robinson, A. P. L.; Hakel, P.; ...

    2015-11-06

    Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. Furthermore, themore » inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.« less

  2. Hydrogen isotope fractionation in methane plasma.

    PubMed

    Robert, François; Derenne, Sylvie; Lombardi, Guillaume; Hassouni, Khaled; Michau, Armelle; Reinhardt, Peter; Duhamel, Rémi; Gonzalez, Adriana; Biron, Kasia

    2017-01-31

    The hydrogen isotope ratio (D/H) is commonly used to reconstruct the chemical processes at the origin of water and organic compounds in the early solar system. On the one hand, the large enrichments in deuterium of the insoluble organic matter (IOM) isolated from the carbonaceous meteorites are interpreted as a heritage of the interstellar medium or resulting from ion-molecule reactions taking place in the diffuse part of the protosolar nebula. On the other hand, the molecular structure of this IOM suggests that organic radicals have played a central role in a gas-phase organosynthesis. So as to reproduce this type of chemistry between organic radicals, experiments based on a microwave plasma of CH4 have been performed. They yielded a black organic residue in which ion microprobe analyses revealed hydrogen isotopic anomalies at a submicrometric spatial resolution. They likely reflect differences in the D/H ratios between the various CHx radicals whose polymerization is at the origin of the IOM. These isotopic heterogeneities, usually referred to as hot and cold spots, are commensurable with those observed in meteorite IOM. As a consequence, the appearance of organic radicals in the ionized regions of the disk surrounding the Sun during its formation may have triggered the formation of organic compounds.

  3. Hydrogen isotope fractionation in methane plasma

    PubMed Central

    Robert, François; Derenne, Sylvie; Lombardi, Guillaume; Hassouni, Khaled; Michau, Armelle; Reinhardt, Peter; Duhamel, Rémi; Gonzalez, Adriana; Biron, Kasia

    2017-01-01

    The hydrogen isotope ratio (D/H) is commonly used to reconstruct the chemical processes at the origin of water and organic compounds in the early solar system. On the one hand, the large enrichments in deuterium of the insoluble organic matter (IOM) isolated from the carbonaceous meteorites are interpreted as a heritage of the interstellar medium or resulting from ion−molecule reactions taking place in the diffuse part of the protosolar nebula. On the other hand, the molecular structure of this IOM suggests that organic radicals have played a central role in a gas-phase organosynthesis. So as to reproduce this type of chemistry between organic radicals, experiments based on a microwave plasma of CH4 have been performed. They yielded a black organic residue in which ion microprobe analyses revealed hydrogen isotopic anomalies at a submicrometric spatial resolution. They likely reflect differences in the D/H ratios between the various CHx radicals whose polymerization is at the origin of the IOM. These isotopic heterogeneities, usually referred to as hot and cold spots, are commensurable with those observed in meteorite IOM. As a consequence, the appearance of organic radicals in the ionized regions of the disk surrounding the Sun during its formation may have triggered the formation of organic compounds. PMID:28096422

  4. Hydrogen isotope fractionation in methane plasma

    NASA Astrophysics Data System (ADS)

    Robert, François; Derenne, Sylvie; Lombardi, Guillaume; Hassouni, Khaled; Michau, Armelle; Reinhardt, Peter; Duhamel, Rémi; Gonzalez, Adriana; Biron, Kasia

    2017-01-01

    The hydrogen isotope ratio (D/H) is commonly used to reconstruct the chemical processes at the origin of water and organic compounds in the early solar system. On the one hand, the large enrichments in deuterium of the insoluble organic matter (IOM) isolated from the carbonaceous meteorites are interpreted as a heritage of the interstellar medium or resulting from ion‑molecule reactions taking place in the diffuse part of the protosolar nebula. On the other hand, the molecular structure of this IOM suggests that organic radicals have played a central role in a gas-phase organosynthesis. So as to reproduce this type of chemistry between organic radicals, experiments based on a microwave plasma of CH4 have been performed. They yielded a black organic residue in which ion microprobe analyses revealed hydrogen isotopic anomalies at a submicrometric spatial resolution. They likely reflect differences in the D/H ratios between the various CHx radicals whose polymerization is at the origin of the IOM. These isotopic heterogeneities, usually referred to as hot and cold spots, are commensurable with those observed in meteorite IOM. As a consequence, the appearance of organic radicals in the ionized regions of the disk surrounding the Sun during its formation may have triggered the formation of organic compounds.

  5. Partial ionization in dense plasmas: comparisons among average-atom density functional models.

    PubMed

    Murillo, Michael S; Weisheit, Jon; Hansen, Stephanie B; Dharma-wardana, M W C

    2013-06-01

    Nuclei interacting with electrons in dense plasmas acquire electronic bound states, modify continuum states, generate resonances and hopping electron states, and generate short-range ionic order. The mean ionization state (MIS), i.e, the mean charge Z of an average ion in such plasmas, is a valuable concept: Pseudopotentials, pair-distribution functions, equations of state, transport properties, energy-relaxation rates, opacity, radiative processes, etc., can all be formulated using the MIS of the plasma more concisely than with an all-electron description. However, the MIS does not have a unique definition and is used and defined differently in different statistical models of plasmas. Here, using the MIS formulations of several average-atom models based on density functional theory, we compare numerical results for Be, Al, and Cu plasmas for conditions inclusive of incomplete atomic ionization and partial electron degeneracy. By contrasting modern orbital-based models with orbital-free Thomas-Fermi models, we quantify the effects of shell structure, continuum resonances, the role of exchange and correlation, and the effects of different choices of the fundamental cell and boundary conditions. Finally, the role of the MIS in plasma applications is illustrated in the context of x-ray Thomson scattering in warm dense matter.

  6. Partial ionization in dense plasmas: Comparisons among average-atom density functional models

    NASA Astrophysics Data System (ADS)

    Murillo, Michael S.; Weisheit, Jon; Hansen, Stephanie B.; Dharma-wardana, M. W. C.

    2013-06-01

    Nuclei interacting with electrons in dense plasmas acquire electronic bound states, modify continuum states, generate resonances and hopping electron states, and generate short-range ionic order. The mean ionization state (MIS), i.e, the mean charge Z of an average ion in such plasmas, is a valuable concept: Pseudopotentials, pair-distribution functions, equations of state, transport properties, energy-relaxation rates, opacity, radiative processes, etc., can all be formulated using the MIS of the plasma more concisely than with an all-electron description. However, the MIS does not have a unique definition and is used and defined differently in different statistical models of plasmas. Here, using the MIS formulations of several average-atom models based on density functional theory, we compare numerical results for Be, Al, and Cu plasmas for conditions inclusive of incomplete atomic ionization and partial electron degeneracy. By contrasting modern orbital-based models with orbital-free Thomas-Fermi models, we quantify the effects of shell structure, continuum resonances, the role of exchange and correlation, and the effects of different choices of the fundamental cell and boundary conditions. Finally, the role of the MIS in plasma applications is illustrated in the context of x-ray Thomson scattering in warm dense matter.

  7. Shock waves and double layers in electron degenerate dense plasma with viscous ion fluids

    SciTech Connect

    Mamun, A. A.; Zobaer, M. S.

    2014-02-15

    The properties of ion-acoustic shock waves and double layers propagating in a viscous degenerate dense plasma (containing inertial viscous ion fluid, non-relativistic and ultra-relativistic degenerate electron fluid, and negatively charged stationary heavy element) is investigated. A new nonlinear equation (viz. Gardner equation with additional dissipative term) is derived by the reductive perturbation method. The properties of the ion-acoustic shock waves and double layers are examined by the analysis of the shock and double layer solutions of this new equation (we would like to call it “M-Z equation”). It is found that the properties of these shock and double layer structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers’ equation. The implications of our results to dense plasmas in astrophysical objects (e.g., non-rotating white dwarf stars) are briefly discussed.

  8. The equation of state and ionization equilibrium of dense aluminum plasma with conductivity verification

    SciTech Connect

    Wang, Kun; Shi, Zongqian; Shi, Yuanjie; Bai, Jun; Wu, Jian; Jia, Shenli

    2015-06-15

    The equation of state, ionization equilibrium, and conductivity are the most important parameters for investigation of dense plasma. The equation of state is calculated with the non-ideal effects taken into consideration. The electron chemical potential and pressure, which are commonly used thermodynamic quantities, are calculated by the non-ideal free energy and compared with results of a semi-empirical equation of state based on Thomas-Fermi-Kirzhnits model. The lowering of ionization potential, which is a crucial factor in the calculation of non-ideal Saha equation, is settled according to the non-ideal free energy. The full coupled non-ideal Saha equation is applied to describe the ionization equilibrium of dense plasma. The conductivity calculated by the Lee-More-Desjarlais model combined with non-ideal Saha equation is compared with experimental data. It provides a possible approach to verify the accuracy of the equation of state and ionization equilibrium.

  9. Equation of state of dense neon and krypton plasmas in the partial ionization regime

    SciTech Connect

    Chen, Q. F. Zheng, J.; Gu, Y. J.; Li, Z. G.

    2015-12-15

    The compression behaviors of dense neon and krypton plasmas over a wide pressure-temperature range are investigated by self-consistent fluid variational theory. The ionization degree and equation of state of dense neon and krypton are calculated in the density-temperature range of 0.01–10 g/cm{sup 3} and 4–50 kK. A region of thermodynamic instability is found which is related to the plasma phase transition. The calculated shock adiabat and principal Hugoniot of liquid krypton are in good agreement with available experimental data. The predicted results of shock-compressed liquid neon are presented, which provide a guide for dynamical experiments or numerical first-principle calculations aimed at studying the compression properties of liquid neon in the partial ionization regime.

  10. Determination of the temperature of a dense plasma from a spectral line shift

    NASA Technical Reports Server (NTRS)

    Sultanov, A. M.; Ageyev, V. A.

    1982-01-01

    The method of maximum spectral line shift proposed by Bardocz, et al, (1966) was successfully applied in the diagnostics of dense plasmas produced by high power pulse discharges. It is pointed out that the effect of the shock wave pressure on the spectral line shift has to be taken into account in order to obtain accurate results with this method for high power discharges. A pressure dependent function was introduced in the expression given by those authors to provide the necessary correction.

  11. Equation of State Measurements of Dense Plasmas Heated by Laser Accelerated MeV Protons

    NASA Astrophysics Data System (ADS)

    Dyer, Gilliss; Bernstein, Aaron; Cho, Byoung-Ick; Grigsby, Will; Dalton, Allen; Shepherd, Ronnie; Ping, Yuan; Chen, Hui; Widmann, Klaus; Ozterhoz, Jens; Ditmire, Todd

    2008-04-01

    Using a fast proton beam generated with an ultra intense laser we have generated and measured the equation of state of solid density plasma at temperatures near 20 eV, a regime in which there have been few previous experimental measurements. The laser accelerated a directional, short pulse of MeV protons, which isochorically heated a solid slab of aluminum. Using two simultaneous, temporally resolved measurements we observed the thermal emission and expansion of the heated foil with picosecond time resolution. With these data we were able to confirm, to within 10%, the SESAME equation-of-state table in this dense plasma region.

  12. Stark broadening of isolated lines from high-Z emitters in dense plasmas

    SciTech Connect

    Weisheit, J.C.; Pollock, E.L.

    1980-09-01

    The joint distribution of the electric microfield and its longitudinal derivative is required for the calculation of line profiles for the He-like ions in very dense plasmas. We used a molecular dynamics code to compute exact distributions in single- and multi-component plasmas, and then we investigated various analytical approximations to these results. We found that a simplified, two-nearest-neighbor scheme leads to surprisingly accurate distribution functions. Our results are illustrated by sample profiles for Ne/sup +8/ and Ar/sup +16/ resonance lines.

  13. Dense Plasma Focus-Based Nanofabrication of III–V Semiconductors: Unique Features and Recent Advances

    PubMed Central

    Mangla, Onkar; Roy, Savita; Ostrikov, Kostya (Ken)

    2015-01-01

    The hot and dense plasma formed in modified dense plasma focus (DPF) device has been used worldwide for the nanofabrication of several materials. In this paper, we summarize the fabrication of III–V semiconductor nanostructures using the high fluence material ions produced by hot, dense and extremely non-equilibrium plasma generated in a modified DPF device. In addition, we present the recent results on the fabrication of porous nano-gallium arsenide (GaAs). The details of morphological, structural and optical properties of the fabricated nano-GaAs are provided. The effect of rapid thermal annealing on the above properties of porous nano-GaAs is studied. The study reveals that it is possible to tailor the size of pores with annealing temperature. The optical properties of these porous nano-GaAs also confirm the possibility to tailor the pore sizes upon annealing. Possible applications of the fabricated and subsequently annealed porous nano-GaAs in transmission-type photo-cathodes and visible optoelectronic devices are discussed. These results suggest that the modified DPF is an effective tool for nanofabrication of continuous and porous III–V semiconductor nanomaterials. Further opportunities for using the modified DPF device for the fabrication of novel nanostructures are discussed as well.

  14. Path Integral Monte Carlo Simulations of Warm Dense Plasmas with mid-Z Elements

    NASA Astrophysics Data System (ADS)

    Driver, Kevin; Soubiran, Francois; Zhang, Shuai; Militzer, Burkhard

    2016-10-01

    Theoretical studies of warm dense plasmas are crucial for improving our knowledge of giant planets, astrophysics, shock physics, and new plasma energy technologies, such as inertial confined fusion. Path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) provide consistent, first-principles descriptions of warm, dense matter over a wide range of density and temperature conditions. Here, we report simulation results for a variety of first- and second-row elements. DFT-MD algorithms are well-suited for low temperatures, while PIMC has been restricted to relatively high temperatures due to the free-particle approximation of the nodal surface. For heavier, second-row elements, we have developed a new, localized nodal surface, which allows us to treat bound states within the PIMC formalism. By combining PIMC and DFT-MD pressures and internal energies, we produce a coherent, first-principles equation of state, bridging the entire warm dense matter regime. Pair-correlation functions and the density of electronic states reveal an evolving plasma structure. The degree of ionization is affected by both temperature and density. Finally, shock Hugoniot curves show an increase in compression as the first and second shells are ionized. Funding provided by the DOE (DE-SC0010517). Computational resources provided by the NCAR/CISL, NERSC, and NASA.

  15. Modeling the hot-dense plasma of the solar interior in and out of thermal equilibrium

    NASA Astrophysics Data System (ADS)

    Lin, Hsiao-Hsuan

    The developments in helioseismology ensure a wealth of studies in solar physics. In particular, with the high precision of the observations of helioseismology, a high-quality solar model is mandated, since even the tiny deviations between a model and the real Sun can be detected. One crucial ingredient of any solar model is the thermodynamics of hot-dense plasmas, in particular the equation of state. This has motivated efforts to develop sophisticated theoretical equations of state (EOS). It is important to realize that for the conditions of solar-interior plasmas, there are no terrestrial laboratory experiments; the only observational constraints come from helioseismology. Among the most successful EOS is so called OPAL EOS, which is part of the Opacity Project at Livermore. It is based on an activity expansion of the quantum plasma, and realized in the so-called "physical picture". One of its main competitor is the so called MHD EOS, which is part of the international Opacity Project (OP), a non-classified multi-country consortium. The approach of MHD is via the so-called "chemical picture". Since OPAL is the most accurate equation of state so far, there has been a call for a public-domain version of it. However, the OPAL code remains proprietary, and its "emulation" makes sense. An additional reason for such a project is that the results form OPAL can only be accessed via tables generated by the OPAL team. Their users do not have the flexibility to change the chemical composition from their end. The earlier MHD-based OPAL emulator worked well with its modifications of the MHD equation of state, which is the Planck-Larkin partition function and its corresponding scattering terms. With this modification, MHD can serve as a OPAL emulator with all the flexibility and accessibility. However, to build a really user-friendly OPAL emulator one should consider CEFF-based OPAL emulator. CEFF itself is already widely used practical EOS which can be easily implemented

  16. Nuclear Fusion Within Extremely Dense Plasma Enhanced by Quantum Particle Waves

    NASA Astrophysics Data System (ADS)

    Miao, Feng; Zheng, Xianjun; Deng, Baiquan

    2015-05-01

    Quantum effects play an enhancement role in p-p chain reactions occurring within stars. Such an enhancement is quantified by a wave penetration factor that is proportional to the density of the participating fuel particles. This leads to an innovative theory for dense plasma, and its result shows good agreement with independent data derived from the solar energy output. An analysis of the first Z-pinch machine in mankind's history exhibiting neutron emission leads to a derived deuterium plasma beam density greater than that of water, with plasma velocities exceeding 10000 km/s. Fusion power could be achieved by the intersection of four such pinched plasma beams with powerful head-on collisions in their common focal region due to the beam and target enhanced reaction. supported by the Fund for the Construction of Graduate Degree of China (No. 2014XWD-S0805)

  17. Microparticle injection effects on microwave transmission through an overly dense plasma layer

    SciTech Connect

    Gillman, Eric D. Amatucci, W. E.; Williams, Jeremiah; Compton, C. S.

    2015-04-15

    Microparticles injected into a plasma have been shown to deplete the free electron population as electrons are collected through the process of microparticles charging to the plasma floating potential. However, these charged microparticles can also act to scatter electromagnetic signals. These experiments investigate microwave penetration through a previously impenetrable overly dense plasma layer as microparticles are injected and the physical phenomena associated with the competing processes that occur due to electron depletion and microwave scattering. The timescales for when each of these competing processes dominates is analyzed in detail. It was found that while both processes play a significant and dominant role at different times, ultimately, transmission through this impenetrable plasma layer can be significantly increased with microparticle injection.

  18. Optically controlled dense current structures driven by relativistic plasma aperture-induced diffraction

    NASA Astrophysics Data System (ADS)

    Gonzalez-Izquierdo, Bruno; Gray, Ross J.; King, Martin; Dance, Rachel J.; Wilson, Robbie; McCreadie, John; Butler, Nicholas M. H.; Capdessus, Remi; Hawkes, Steve; Green, James S.; Borghesi, Marco; Neely, David; McKenna, Paul

    2016-05-01

    The collective response of charged particles to intense fields is intrinsic to plasma accelerators and radiation sources, relativistic optics and many astrophysical phenomena. Here we show that a relativistic plasma aperture is generated in thin foils by intense laser light, resulting in the fundamental optical process of diffraction. The plasma electrons collectively respond to the resulting laser near-field diffraction pattern, producing a beam of energetic electrons with a spatial structure that can be controlled by variation of the laser pulse parameters. It is shown that static electron-beam and induced-magnetic-field structures can be made to rotate at fixed or variable angular frequencies depending on the degree of ellipticity in the laser polarization. The concept is demonstrated numerically and verified experimentally, and is an important step towards optical control of charged particle dynamics in laser-driven dense plasma sources.

  19. Stark Broadening Analysis Using Optical Spectroscopy of the Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Ross, Patrick; Bennett, Nikki; Dutra, Eric; Hagen, E. Chris; Hsu, Scott; Hunt, Gene; Koch, Jeff; Waltman, Tom; NSTec DPF Team

    2015-11-01

    To aid in validating numerical modeling of MA-class dense plasma focus (DPF) devices, spectroscopic measurements of the Gemini Dense Plasma Focus (DPF) were performed using deuterium and deuterium/dopant (argon/krypton) gas. The spectroscopic measurements were made using a fiber-coupled spectrometer and streak camera. Stark line-broadening analysis was applied to the deuterium beta emission (486 nm) in the region near the breakdown of the plasma and during the run-down and run-in phases of the plasma evolution. Densities in the range of 1e17 to low 1e18 cm-3 were obtained. These values are in agreement with models of the DPF performed using the LSP code. The spectra also show a rise and fall with time, indicative of the plasma sheath passing by the view port. Impurity features were also identified in the spectra which grew in intensity as the gas inside the DPF was discharged repeatedly without cycling. Implications of this impurity increase for D-T discharges (without fresh gas fills between every discharge) will be discussed. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946, and by Los Alamos National Laboratory, under Contract no. DE-AC52-06NA25396 with the U.S. Department of Energy. DOE/NV/25946-2515.

  20. Ultrafast electron kinetics in short pulse laser-driven dense hydrogen

    NASA Astrophysics Data System (ADS)

    Zastrau, U.; Sperling, P.; Fortmann-Grote, C.; Becker, A.; Bornath, T.; Bredow, R.; Döppner, T.; Fennel, T.; Fletcher, L. B.; Förster, E.; Göde, S.; Gregori, G.; Harmand, M.; Hilbert, V.; Laarmann, T.; Lee, H. J.; Ma, T.; Meiwes-Broer, K. H.; Mithen, J. P.; Murphy, C. D.; Nakatsutsumi, M.; Neumayer, P.; Przystawik, A.; Skruszewicz, S.; Tiggesbäumker, J.; Toleikis, S.; White, T. G.; Glenzer, S. H.; Redmer, R.; Tschentscher, T.

    2015-11-01

    Dense cryogenic hydrogen is heated by intense femtosecond infrared laser pulses at intensities of {10}15-{10}16 W cm-2. Three-dimensional particle-in-cell (PIC) simulations predict that this heating is limited to the skin depth, causing an inhomogeneously heated outer shell with a cold core and two prominent temperatures of about 25 and 40 {eV} for simulated delay times up to +70 {fs} after the laser pulse maximum. Experimentally, the time-integrated emitted bremsstrahlung in the spectral range of 8-18 nm was corrected for the wavelength-dependent instrument efficiency. The resulting spectrum cannot be fit with a single temperature bremsstrahlung model, and the best fit is obtained using two temperatures of about 13 and 30 eV. The lower temperatures in the experiment can be explained by missing energy-loss channels in the simulations, as well as the inclusion of hot, non-Maxwellian electrons in the temperature calculation. We resolved the time-scale for laser-heating of hydrogen, and PIC results for laser-matter interaction were successfully tested against the experiment data.

  1. Ultrafast electron kinetics in short pulse laser-driven dense hydrogen

    SciTech Connect

    Zastrau, U.; Sperling, P.; Fortmann-Grote, C.; Bornath, T.; Bredow, R.; Doppner, T.; Fennel, T.; Fletcher, L. B.; Forster, E.; Gode, S.; Gregori, G.; Harmand, M.; Hilbert, V.; Laarmann, T.; Lee, H. J.; Ma, T.; Meiwes-Broer, K. H.; Mithen, J. P.; Murphy, C. D.; Nakatsutsumi, M.; Neumayer, P.; Przystawik, A.; Skruszewicz, S.; Tiggesbaumker, J.; Toleikis, S.; White, T. G.; Glenzer, S. H.; Redmer, R.; Tschentscher, T.

    2015-09-25

    Dense cryogenic hydrogen is heated by intense femtosecond infrared laser pulses at intensities of ${10}^{15}-{10}^{16}\\;$ W cm–2. Three-dimensional particle-in-cell (PIC) simulations predict that this heating is limited to the skin depth, causing an inhomogeneously heated outer shell with a cold core and two prominent temperatures of about $25$ and $40\\;\\mathrm{eV}$ for simulated delay times up to $+70\\;\\mathrm{fs}$ after the laser pulse maximum. Experimentally, the time-integrated emitted bremsstrahlung in the spectral range of 8–18 nm was corrected for the wavelength-dependent instrument efficiency. The resulting spectrum cannot be fit with a single temperature bremsstrahlung model, and the best fit is obtained using two temperatures of about 13 and $30\\;$eV. The lower temperatures in the experiment can be explained by missing energy-loss channels in the simulations, as well as the inclusion of hot, non-Maxwellian electrons in the temperature calculation. In conclusion, we resolved the time-scale for laser-heating of hydrogen, and PIC results for laser–matter interaction were successfully tested against the experiment data.

  2. Ultrafast electron kinetics in short pulse laser-driven dense hydrogen

    DOE PAGES

    Zastrau, U.; Sperling, P.; Fortmann-Grote, C.; ...

    2015-09-25

    Dense cryogenic hydrogen is heated by intense femtosecond infrared laser pulses at intensities ofmore » $${10}^{15}-{10}^{16}\\;$$ W cm–2. Three-dimensional particle-in-cell (PIC) simulations predict that this heating is limited to the skin depth, causing an inhomogeneously heated outer shell with a cold core and two prominent temperatures of about $25$ and $$40\\;\\mathrm{eV}$$ for simulated delay times up to $$+70\\;\\mathrm{fs}$$ after the laser pulse maximum. Experimentally, the time-integrated emitted bremsstrahlung in the spectral range of 8–18 nm was corrected for the wavelength-dependent instrument efficiency. The resulting spectrum cannot be fit with a single temperature bremsstrahlung model, and the best fit is obtained using two temperatures of about 13 and $$30\\;$$eV. The lower temperatures in the experiment can be explained by missing energy-loss channels in the simulations, as well as the inclusion of hot, non-Maxwellian electrons in the temperature calculation. In conclusion, we resolved the time-scale for laser-heating of hydrogen, and PIC results for laser–matter interaction were successfully tested against the experiment data.« less

  3. Hydrogen uptake into silicon from an ECR plasma

    SciTech Connect

    Wampler, W.R.; Barbour, J.C.

    1993-12-01

    The concentration of hydrogen in solution near the surface of silicon exposed to an electron cyclotron resonance (ECR) plasma was determined by measuring the flux of hydrogen permeating to subsurface microcavities. The energy and flux of hydrogen impinging onto the surface from the plasma was also measured. A model is described which predicts the concentration of hydrogen in solution from the energy and flux of the impinging hydrogen. The measured solution concentrations were {approximately}10{sup {minus}9} H/Si at 600{degrees}C and {approximately}10{sup {minus}8} H/Si at 400{degrees}C, in fairly good agreement with the model. The absence of accumulation of immobile hydrogen near the surface indicates that lattice defects, which strongly trap hydrogen, were not produced by the ECR plasma. This study establishes a connection between the properties of the ECR plasma and the concentration of hydrogen in silicon samples exposed to the plasma, which allows improved control over passivation of defects and dopants.

  4. Research of surface plasma resonance optical fiber hydrogen sensor

    NASA Astrophysics Data System (ADS)

    Ou, Zhonghua; Guo, Xiaowei; Chen, Dejun; Dai, Zhiyong; Peng, Zengshou; Liu, Yongzhi

    2008-12-01

    An optical fiber hydrogen sensor based on the measuring principle of surface plasma resonance is introduced. The structure of the hydrogen-sensitive head which is coated with Pd-Ag alloy film on the surface of the etched optical fiber is investigated theoretically. When hydrogen gas is absorbed into the Pd thin layer of the sensing head, the Pd hydride is formed and then the refraction index of the etched optical fiber surface will be changed with different hydrogen gas concentration. The surface plasma wave is stimulated by the light wave in optical fiber and the surface plasma resonance occurs between the thin metal layer and the medium surface of hydrogen gas. The Pd-Ag alloy film thickness versus the sensitivity of hydrogen sensing head is analyzed and optimized via the numerical method. The sensing head which is based on surface plasma resonance is manufactured and used in the experiment system of hydrogen gas detecting, and the experiment results demonstrate that the detecting system has high sensitivity with the hydrogen concentration in the range of 0%-4%, the accuracy, resolution and response time are respectively 5%, 0.1% and 30s. This sensor structure can be applied to detecting the low concentration of hydrogen gas.

  5. An experimental study of the pulsed outflow of a dense plasma into a submerged medium - Axisymmetric expansion regimes

    NASA Astrophysics Data System (ADS)

    Aleksandrov, A. F.; Timofeev, I. B.; Iusupaliev, U.

    1991-02-01

    Pulsed outflow of a dense plasma into a submerged medium was investigated experimentally in the case where plasma expansion is determined completely by gasdynamic processes. Based on experimental data, a dimensionless parameter is proposed which determines the regime of plasma outflow. The effects of the plasmatron nozzle diameter, specific energy input into the discharge, and medium gas pressure are discussed.

  6. Effect of argon addition on plasma parameters and dust charging in hydrogen plasma

    SciTech Connect

    Kakati, B. Kausik, S. S.; Saikia, B. K.; Bandyopadhyay, M.; Saxena, Y. C.

    2014-10-28

    Experimental results on effect of adding argon gas to hydrogen plasma in a multi-cusp dusty plasma device are reported. Addition of argon modifies plasma density, electron temperature, degree of hydrogen dissociation, dust current as well as dust charge. From the dust charging profile, it is observed that the dust current and dust charge decrease significantly up to 40% addition of argon flow rate in hydrogen plasma. But beyond 40% of argon flow rate, the changes in dust current and dust charge are insignificant. Results show that the addition of argon to hydrogen plasma in a dusty plasma device can be used as a tool to control the dust charging in a low pressure dusty plasma.

  7. Dense pair plasma generation by two laser pulses colliding in a cylinder channel

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Xun; Ma, Yan-Yun; Yu, Tong-Pu; Zhao, Jun; Yang, Xiao-Hu; Zou, De-Bin; Zhang, Guo-Bo; Zhao, Yuan; Yang, Jing-Kang; Li, Han-Zhen; Zhuo, Hong-Bin; Shao, Fu-Qiu; Kawata, Shigeo

    2017-03-01

    An all-optical scheme for high-density pair plasmas generation is proposed by two laser pulses colliding in a cylinder channel. Two dimensional particle-in-cell simulations show that, when the first laser pulse propagates in the cylinder, electrons are extracted out of the cylinder inner wall and accelerated to high energies. These energetic electrons later run into the second counter-propagating laser pulse, radiating a large amount of high-energy gamma photons via the Compton back-scattering process. The emitted gamma photons then collide with the second laser pulse to initiate the Breit–Wheeler process for pairs production. Due to the strong self-generated fields in the cylinder, positrons are confined in the channel to form dense pair plasmas. Totally, the maximum density of pair plasmas can be 4.60× {10}27 {{{m}}}-3, for lasers with an intensity of 4× {10}22 {{W}}\\cdot {{cm}}-2. Both the positron yield and density are tunable by changing the cylinder radius and the laser parameters. The generated dense pair plasmas can further facilitate investigations related to astrophysics and particle physics. Project supported by the National Natural Science Foundation (Grant Nos. 11475260, 11305264, 11622547, 11375265, and 11474360), the National Basic Research Program of China (Grant No. 2013CBA01504), the Research Project of National University of Defense Technology, China (Contract No. JC14-02-02), and the Science Challenge Program, China (Grant No. JCKY2016212A505).

  8. Plasma-chemical conversion of hydrogen sulfide into hydrogen and sulfur

    SciTech Connect

    Harkness, J.B.L.; Doctor, R.D.; Daniels, E.J.

    1993-09-01

    A waste-treatment process that recovers both hydrogen and sulfur from hydrogen-sulfide-contaminated industrial wastes is being developed to replace the Claus technology, which recovers only sulfur. The proposed process is based on research reported in the Soviet technical literature and uses microwave (or radio-frequency) energy to initiate plasma-chemical reactions that dissociate hydrogen sulfide into elemental hydrogen and sulfur. In the plasma-chemical process, the gaseous stream would be purified and separated into streams containing the product hydrogen, hydrogen sulfide for recycle to the plasma reactor, and the process purge containing carbon dioxide and water. Since unconverted hydrogen sulfide is recycled to the plasma reactor, the plasma-chemical process has the potential for sulfur recoveries in excess of 99% without the additional tail-gas clean-up processes associated with the Claus technology. Laboratory experiments with pure hydrogen sulfide have confirmed that conversions of over 90% per pass are possible. Experiments with impurities typical of petroleum refinery and natural gas production acid gases have demonstrated that these impurities are compatible with the plasma dissociation process and do not appear to create new waste-treatment problems. Other experiments show that the cyclonic-flow pattern hypothesized by the Russian theoretical analysis of the plasma-chemical process can substantially decrease energy requirements for hydrogen sulfide dissociation while increasing conversion. This process has several advantages over the current Claus-plus-tail-gas-cleanup technology. The primary advantage is the potential for recovering hydrogen more cheaply than the direct production of hydrogen. The difference could amount to an energy savings of 40 {times} 10{sup 15} to 70 {times} 10{sup 15} J/yr in the refining industry, for an annual savings of $500 million to $1,000 million.

  9. Improved adhesion of dense silica coatings on polymers by atmospheric plasma pretreatment.

    PubMed

    Cui, Linying; Ranade, Alpana N; Matos, Marvi A; Dubois, Geraud; Dauskardt, Reinhold H

    2013-09-11

    Oxygen atmospheric plasma was used to pretreat polycarbonate (PC) and stretched poly(methyl methacrylate) (PMMA) surfaces in order to enhance the adhesion of the dense silica coatings deposited by atmospheric plasma on the polymer substrates. The treatment time and chemical structure of the polymers were found to be important factors. For PC, a short treatment increased the adhesion energy, while longer treatment times decreased the adhesion. In contrast, plasma pretreatment monotonically decreased the adhesion of PMMA, and pristine PMMA exhibited much higher adhesion than the PC counterpart. We found that adhesion enhancement was achieved through improved chemical bonding, chain interdiffusion, and mechanical interlocking at the coating/substrate interface, after a short atmospheric plasma treatment. Decreased adhesion resulted from overoxidation and low-molecular-weight weak layer formation on the polymer surface by prolonged atmospheric plasma treatment. The dramatic differences in the behavior of PC and PMMA in relation to the plasma treatment time were due to their dissimilar resistance to atmospheric plasma exposure.

  10. Dust-Coulomb and dust-acoustic wave propagation in dense dusty plasmas with high fugacity

    NASA Astrophysics Data System (ADS)

    Rao, N. N.

    2000-03-01

    A detailed investigation of electrostatic dust wave modes in unmagnetized dusty plasmas consisting of electrons, ions and dust grains has been carried out over a wide range of dust fugacity and wave frequency by using fluid as well as kinetic (Vlasov) theories. The dust fugacity parameter is defined by f≡4πnd0λD2R˜ND R/λD where nd0, λD and R are respectively the dust number density, the plasma Debye length and the grain size (radius), and ND=4πnd0λD3/3 is the dust plasma parameter. Dusty plasmas are considered to be tenuous, dilute or dense according as f≪1, ˜1, or ≫1. In particular, attention is focused on the "dust-acoustic waves" (DAWs) and the "dust-Coulomb waves" (DCWs) which exist in the tenuous (low fugacity) and the dense (high fugacity) regimes, respectively, when the wave frequency is much smaller than the grain charging frequency. Unlike the DAWs, which exist even with constant grain charge, the DCWs [N. N. Rao, Phys. Plasmas 6, 4414 (1999)] are the normal modes associated with grain charge fluctuations, and exist in dense dusty plasmas. In the long wavelength limit, the DCW phase speed scales as ˜CDA/√f where CDA is the DAW phase speed. In the dilute (medium fugacity) regime, the two modes merge into a single mode, which may be called the "dust charge-density wave" (DCDW) since the latter involves contributions arising from both the DAW and the DCW. On the other hand, for frequencies much larger than the charging frequency, DAWs are shown to exist also in the dilute regime. The real frequency as well as the damping rate in each case are explicitly calculated from both the fluid as well the kinetic theories, and a comparison between the two has been carried out. In the allowed fugacity regimes (tenuous, dilute or dense), all the three waves are weakly damped and, hence, can propagate as normal modes. The present analysis of wave propagation in dusty plasmas over different fugacity regimes suggests the introduction of a new length scale

  11. Microwave plasma generation of hydrogen atoms for rocket propulsion

    NASA Technical Reports Server (NTRS)

    Chapman, R.; Filpus, J.; Morin, T.; Snellenberger, R.; Asmussen, J.; Hawley, M.; Kerber, R.

    1981-01-01

    A flow microwave plasma reaction system is used to study the conversion of hydrogen to hydrogen atoms as a function of pressure, power density, cavity tuning, cavity mode, and time in the plasma zone. Hydrogen atom concentration is measured down-stream from the plasma by NOCl titration. Extensive modeling of the plasma and recombination zones is performed with the plasma zone treated as a backmix reaction system and the recombination zone treated as a plug flow. The thermodynamics and kinetics of the recombination process are examined in detail to provide an understanding of the conversion of recombination energy to gas kinetic energy. It is found that cavity tuning, discharge stability, and optimum power coupling are critically dependent on the system pressure, but nearly independent of the flow rate.

  12. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    NASA Astrophysics Data System (ADS)

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2016-07-01

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. These simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.

  13. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter.

    PubMed

    Bang, W; Albright, B J; Bradley, P A; Vold, E L; Boettger, J C; Fernández, J C

    2016-07-12

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1-100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. These simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.

  14. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    DOE PAGES

    Bang, Woosuk; Albright, Brian James; Bradley, Paul Andrew; ...

    2016-07-12

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly withmore » temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. In conclusion, these simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.« less

  15. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    SciTech Connect

    Bang, Woosuk; Albright, Brian James; Bradley, Paul Andrew; Vold, Erik Lehman; Boettger, Jonathan Carl; Fernández, Juan Carlos

    2016-07-12

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. In conclusion, these simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.

  16. Mechanisms for multi-scale structures in dense degenerate astrophysical plasmas

    NASA Astrophysics Data System (ADS)

    Shatashvili, N. L.; Mahajan, S. M.; Berezhiani, V. I.

    2016-02-01

    Two distinct routes lead to the creation of multi-scale equilibrium structures in dense degenerate plasmas, often met in astrophysical conditions. By analyzing an e-p-i plasma consisting of degenerate electrons and positrons with a small contamination of mobile classical ions, we show the creation of a new macro scale L_{macro} (controlled by ion concentration). The temperature and degeneracy enhancement effective inertia of bulk e-p components also makes the effective skin depths larger (much larger) than the standard skin depth. The emergence of these intermediate and macro scales lends immense richness to the process of structure formation, and vastly increases the channels for energy transformations. The possible role played by this mechanism in explaining the existence of large-scale structures in astrophysical objects with degenerate plasmas, is examined.

  17. Dense Plasma Focus Z-pinches for High Gradient Particle Acceleration

    SciTech Connect

    Tang, V; Adams, M L; Rusnak, B

    2009-07-24

    The final Z-pinch stage of a Dense Plasma Focus (DPF) could be used as a simple, compact, and potentially rugged plasma-based high-gradient accelerator with fields at the 100 MV/m level. In this paper we review previously published experimental beam data that indicate the feasibility of such an DPF-based accelerator, qualitatively discuss the physical acceleration processes in terms of the induced voltages, and as a starting point examine the DPF acceleration potential by numerically applying a self-consistent DPF system model that includes the induced voltage from both macroscopic and instability driven plasma dynamics. Applications to the remote detection of high explosives and a multi-staged acceleration concept are briefly discussed.

  18. Gamma ray measurements with photoconductive detectors using a dense plasma focus

    SciTech Connect

    May, M. J. Brown, G. V.; Halvorson, C.; Schmidt, A.; Bower, D.; Tran, B.; Lewis, P.; Hagen, C.

    2014-11-15

    Photons in the MeV range emitted from the dense plasma focus (DPF) at the NSTec North Las Vegas Facility have been measured with both neutron-damaged GaAs and natural diamond photoconductive detectors (PCDs). The DPF creates or “pinches” plasmas of various gases (e.g., H{sub 2}, D{sub 2}, Ne, Ar., etc.) that have enough energy to create MeV photons from either bremsstrahlung and/or (n,n{sup ′}) reactions if D{sub 2} gas is used. The high bandwidth of the PCDs enabled the first ever measurement of the fast micro-pinches present in DPF plasmas. Comparisons between a slower more conventional scintillator/photomultiplier tube based nuclear physics detectors were made to validate the response of the PCDs to fast intense MeV photon signals. Significant discrepancies in the diamond PCD responses were evident.

  19. The Modeling of the Continuous Emission Spectrum of a Dense Non-ideal Plasma in Optical Region

    SciTech Connect

    Mihajlov, Anatolij A.; Sakan, Nenad M.; Sreckovic, Vladimir A.

    2007-09-28

    This paper presents a study of the usability of the Coulomb cut-off potential for the calculation of bound-free and free-free cross sections. It covers the condition in dense plasma where there is no good theory that covers the optical properties of dense plasma. The presented quantum mechanical model has given a good agreement with the experimental data. The ideas for further development of the presented calculations are shown.

  20. Dense electron-positron plasmas and bursts of gamma-rays from laser-generated quantum electrodynamic plasmas

    SciTech Connect

    Ridgers, C. P.; Bell, A. R.; Brady, C. S.; Bennett, K.; Arber, T. D.; Duclous, R.; Kirk, J. G.

    2013-05-15

    In simulations of a 12.5 PW laser (focussed intensity I=4×10{sup 23}Wcm{sup −2}) striking a solid aluminum target, 10% of the laser energy is converted to gamma-rays. A dense electron-positron plasma is generated with a maximum density of 10{sup 26}m{sup −3}, seven orders of magnitude denser than pure e{sup −} e{sup +} plasmas generated with 1PW lasers. When the laser power is increased to 320 PW (I=10{sup 25}Wcm{sup −2}), 40% of the laser energy is converted to gamma-ray photons and 10% to electron-positron pairs. In both cases, there is strong feedback between the QED emission processes and the plasma physics, the defining feature of the new “QED-plasma” regime reached in these interactions.

  1. Modeling of Dense Plasma Effects in Short-Pulse Laser Experiments

    NASA Astrophysics Data System (ADS)

    Walton, Timothy; Golovkin, Igor; Macfarlane, Joseph; Prism Computational Sciences, Madison, WI Team

    2016-10-01

    Warm and Hot Dense Matter produced in short-pulse laser experiments can be studied with new high resolving power x-ray spectrometers. Data interpretation implies accurate modeling of the early-time heating dynamics and the radiation conditions that are generated. Producing synthetic spectra requires a model that describes the major physical processes that occur inside the target, including the hot-electron generation and relaxation phases and the effect of target heating. An important issue concerns the sensitivity of the predicted K-line shifts to the continuum lowering model that is used. We will present a set of PrismSPECT spectroscopic simulations using various continuum lowering models: Hummer/Mihalas, Stewart-Pyatt, and Ecker-Kroll and discuss their effect on the formation of K-shell features. We will also discuss recently implemented models for dense plasma shifts for H-like, He-like and neutral systems.

  2. Nonlinear ion modes in a dense plasma with strongly coupled ions and degenerate electron fluids

    SciTech Connect

    Shukla, P. K.; Mamun, A. A.; Mendis, D. A.

    2011-08-15

    The properties of solitary and shock structures associated with nonlinear ion modes in a dense plasma with strongly coupled nondegenerate ions and degenerate electron fluids are presented. For this purpose, we have used the viscoelastic fluid model for the ions, the inertialess electron momentum equation with weakly and ultrarelativistic pressure laws for the degenerate electron fluids, and Poisson's equation to derive the Burgers and Kortweg-de Vries equations. Possible stationary solutions of the latter are the shock and solitary structures, respectively. It is found that the speed, amplitude, and width of the shock and solitary waves critically depend on the strong coupling between ions and electron degeneracy effects. The relevance of our investigation to the role of localized excitations in dense astrophysical objects is briefly discussed.

  3. Nanosecond CO2 laser interaction with a dense helium Z-pinch plasma

    NASA Astrophysics Data System (ADS)

    Voss, D. F.

    A short pulse CO2 laser system was constructed to investigate the interaction of intense electromagnetic radiation with dense plasma. The laser was focused perpendicular to the axis of a linear helium Z-pinch plasma and properties of the transmitted beam were monitored. Transmitted beam intensity and spatial distribution were measured as functions of incident intensity and interaction time. The results of the experiments with the overdense plasma were found to be consistent with plasma hydrodynamic theory. A 40 nanosecond pulse was sufficiently long to burn through the plasma, but a 4 nanosecond pulse was not. The 4 nanosecond pulse was long enough to form a local density depression in the underdense plasma and density gradients steep enough to produce Fresnel diffraction, despite the absence of a critical surface. The resultant change in refractive index could cause thermal self-focusing. The transmission measurement was not found to be consistent with a simple model of inverse bremsstrahlung absorption. At an intensity of 10 to the 12th power W/cu/cm there was a sharp decrease in transmission. This suggests the possibility of either increased absorption due to enhanced ionization or increased reflection due to simulated Brillouin backscatter.

  4. Magnetoacoustic solitons and shocks in dense astrophysical plasmas with relativistic degenerate electrons

    NASA Astrophysics Data System (ADS)

    Irfan, M.; Ali, S.; Mirza, Arshad M.

    2016-02-01

    Two-fluid quantum magnetohydrodynamic (QMHD) equations are employed to investigate linear and nonlinear properties of the magnetosonic waves in a semi-relativistic dense plasma accounting for degenerate relativistic electrons. In the linear analysis, a plane wave solution is used to derive the dispersion relation of magnetosonic waves, which is significantly modified due to relativistic degenerate electrons. However, for a nonlinear investigation of solitary and shock waves, we employ the reductive perturbation technique for the derivation of Korteweg-de Vries (KdV) and Korteweg-de Vries Burger (KdVB) equations, admitting nonlinear wave solutions. Numerically, it is shown that the wave frequency decreases to attain a lowest possible value at a certain critical number density Nc(0), and then increases beyond Nc(0) as the plasma number density increases. Moreover, the relativistic electrons and associated pressure degeneracy lead to a reduction in the spatial extents of the magnetosonic waves and a strengthening of the shock amplitude. The results might be important for understanding the linear and nonlinear magnetosonic excitations in dense astrophysical plasmas, such as in white dwarfs, magnetars and neutron stars, etc., where relativistic degenerate electrons are present.

  5. Development and Benchmarking of a Hybrid PIC Code For Dense Plasmas and Fast Ignition

    SciTech Connect

    Witherspoon, F. Douglas; Welch, Dale R.; Thompson, John R.; MacFarlane, Joeseph J.; Phillips, Michael W.; Bruner, Nicki; Mostrom, Chris; Thoma, Carsten; Clark, R. E.; Bogatu, Nick; Kim, Jin-Soo; Galkin, Sergei; Golovkin, Igor E.; Woodruff, P. R.; Wu, Linchun; Messer, Sarah J.

    2014-05-20

    Radiation processes play an important role in the study of both fast ignition and other inertial confinement schemes, such as plasma jet driven magneto-inertial fusion, both in their effect on energy balance, and in generating diagnostic signals. In the latter case, warm and hot dense matter may be produced by the convergence of a plasma shell formed by the merging of an assembly of high Mach number plasma jets. This innovative approach has the potential advantage of creating matter of high energy densities in voluminous amount compared with high power lasers or particle beams. An important application of this technology is as a plasma liner for the flux compression of magnetized plasma to create ultra-high magnetic fields and burning plasmas. HyperV Technologies Corp. has been developing plasma jet accelerator technology in both coaxial and linear railgun geometries to produce plasma jets of sufficient mass, density, and velocity to create such imploding plasma liners. An enabling tool for the development of this technology is the ability to model the plasma dynamics, not only in the accelerators themselves, but also in the resulting magnetized target plasma and within the merging/interacting plasma jets during transport to the target. Welch pioneered numerical modeling of such plasmas (including for fast ignition) using the LSP simulation code. Lsp is an electromagnetic, parallelized, plasma simulation code under development since 1995. It has a number of innovative features making it uniquely suitable for modeling high energy density plasmas including a hybrid fluid model for electrons that allows electrons in dense plasmas to be modeled with a kinetic or fluid treatment as appropriate. In addition to in-house use at Voss Scientific, several groups carrying out research in Fast Ignition (LLNL, SNL, UCSD, AWE (UK), and Imperial College (UK)) also use LSP. A collaborative team consisting of HyperV Technologies Corp., Voss Scientific LLC, FAR-TECH, Inc., Prism

  6. Hydrogen Generation from the Dissociation of Water Using Microwave Plasmas

    NASA Astrophysics Data System (ADS)

    Yong, Ho Jung; Soo Ouk, Jang; Hyun Jong, You

    2013-06-01

    Hydrogen is produced by direct dissociation of water vapor, i.e., splitting water molecules by the electrons in water plasma at low pressure (<10-50 Torr) using microwave plasma discharge. This condition generates a high electron temperature, which facilitates the direct dissociation of water molecules. A microwave plasma source is developed, utilizing the magnetron of a microwave oven and a TE10 rectangular waveguide. The quantity of the generated hydrogen is measured using a residual gas analyzer. The electron density and temperature are measured by a Langmuir probe, and the neutral temperature is calculated from the OH line intensity.

  7. Nonlinear electrostatic excitations of charged dust in degenerate ultra-dense quantum dusty plasmas

    SciTech Connect

    Abdelsalam, U. M.; Ali, S.; Kourakis, I.

    2012-06-15

    The linear and nonlinear properties of low-frequency electrostatic excitations of charged dust particles (or defects) in a dense collisionless, unmagnetized Thomas-Fermi plasma are investigated. A fully ionized three-component model plasma consisting of electrons, ions, and negatively charged massive dust grains is considered. Electrons and ions are assumed to be in a degenerate quantum state, obeying the Thomas-Fermi density distribution, whereas the inertial dust component is described by a set of classical fluid equations. Considering large-amplitude stationary profile travelling-waves in a moving reference frame, the fluid evolution equations are reduced to a pseudo-energy-balance equation, involving a Sagdeev-type potential function. The analysis describes the dynamics of supersonic dust-acoustic solitary waves in Thomas-Fermi plasmas, and provides exact predictions for their dynamical characteristics, whose dependence on relevant parameters (namely, the ion-to-electron Fermi temperature ratio, and the dust concentration) is investigated. An alternative route is also adopted, by assuming weakly varying small-amplitude disturbances off equilibrium, and then adopting a multiscale perturbation technique to derive a Korteweg-de Vries equation for the electrostatic potential, and finally solving in terms for electric potential pulses (electrostatic solitons). A critical comparison between the two methods reveals that they agree exactly in the small-amplitude, weakly superacoustic limit. The dust concentration (Havnes) parameter h=Z{sub d0}n{sub d0}/n{sub e0} affects the propagation characteristics by modifying the phase speed, as well as the electron/ion Fermi temperatures. Our results aim at elucidating the characteristics of electrostatic excitations in dust-contaminated dense plasmas, e.g., in metallic electronic devices, and also arguably in supernova environments, where charged dust defects may occur in the quantum plasma regime.

  8. Acceleration of Dense Flowing Plasmas using ICRF Power in the VASIMR Experiment

    NASA Astrophysics Data System (ADS)

    Squire, Jared P.

    2005-09-01

    ICRF power in the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept energizes ions (> 100 eV) in a diverging magnetic field to accelerate a dense (˜ 1019 m-3) flowing plasma to velocities useful for space propulsion (˜100 km/s). Theory predicts that an ICRF slow wave launched from the high field side of the resonance will propagate in the magnetic beach to absorb nearly all of the power at the resonance, thus efficiently converting the RF power to ion kinetic energy. The plasma flows through the resonance only once, so the ions are accelerated in a single pass. This process has proven efficient (˜ 70%) with an ICRF power level of 1.5 kW at about 3.6 MHz in the VASIMR experiment, VX-30, using deuterium plasma created by a helicon operating in flowing mode. We have measured ICRF plasma loading up to 2 ohms, consistent with computational predictions made using Oak Ridge National Laboratory's EMIR code. Recent helicon power upgrades (20 kW at 13.56 MHz) have enabled a 5 cm diameter target plasma for ICRF with an ion flux of over 3×10 20 s-1 and a high degree of ionization. This paper summarizes our ICRF results and presents the latest helicon developments in VX-30.

  9. Acceleration of Dense Flowing Plasmas using ICRF Power in the VASIMR Experiment

    SciTech Connect

    Squire, Jared P.

    2005-09-26

    ICRF power in the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept energizes ions (> 100 eV) in a diverging magnetic field to accelerate a dense ({approx} 1019 m-3) flowing plasma to velocities useful for space propulsion ({approx}100 km/s). Theory predicts that an ICRF slow wave launched from the high field side of the resonance will propagate in the magnetic beach to absorb nearly all of the power at the resonance, thus efficiently converting the RF power to ion kinetic energy. The plasma flows through the resonance only once, so the ions are accelerated in a single pass. This process has proven efficient ({approx} 70%) with an ICRF power level of 1.5 kW at about 3.6 MHz in the VASIMR experiment, VX-30, using deuterium plasma created by a helicon operating in flowing mode. We have measured ICRF plasma loading up to 2 ohms, consistent with computational predictions made using Oak Ridge National Laboratory's EMIR code. Recent helicon power upgrades (20 kW at 13.56 MHz) have enabled a 5 cm diameter target plasma for ICRF with an ion flux of over 3x10 20 s-1 and a high degree of ionization. This paper summarizes our ICRF results and presents the latest helicon developments in VX-30.

  10. High-Energy Ion Acceleration Mechanisms in a Dense Plasma Focus Z-Pinch

    NASA Astrophysics Data System (ADS)

    Higginson, D. P.; Link, A.; Schmidt, A.; Welch, D.

    2016-10-01

    The compression of a Z-pinch plasma, specifically in a dense plasma focus (DPF), is known to accelerate high-energy electrons, ions and, if using fusion-reactant ions (e.g. D, T), neutrons. The acceleration of particles is known to coincide with the peak constriction of the pinch, however, the exact physical mechanism responsible for the acceleration remains an area of debate and uncertainty. Recent work has suggested that this acceleration is linked to the growth of an m =0 (sausage) instability that evacuates a region of low-density, highly-magnetized plasma and creates a strong (>MV/cm) electric field. Using the fully kinetic particle-in-cell code LSP in 2D-3V, we simulate the compression of a 2 MA, 35 kV DPF plasma and investigate in detail the formation of the electric field. The electric field is found to be predominantly in the axial direction and driven via charge-separation effects related to the resistivity of the kinetic plasma. The strong electric and magnetic fields are shown to induce non-Maxwellian distributions in both the ions and electrons and lead to the acceleration of high-energy tails. We compare the results in the kinetic simulations to assumptions of magnetohydrodynamics (MHD). Prepared by LLNL under Contract DE-AC52-07NA27344.

  11. A New Parameter Regime for Dust in Plasma: the Case of Dense and Supersonic Plasma Flows

    SciTech Connect

    Ticos, Catalin M.; Wang Zhehui; Wurden, Glen A.

    2008-09-07

    The co-existence between charged micron-size particulates of matter and plasma electrons and ions can lead to interesting physics phenomena. Some of the most spectacular observations in laboratory low ionized gases include the formation of aligned dust structures, the propagation of dust waves or self-organization leading to dust voids. Here, the dust dynamics is established by the forces of gravity, of electrostatic interaction with electric fields within the plasma, of friction with the neutral gas, and by the Coulomb repulsion between grains. Measurements of dust trajectories have been carried out in situ when the plasma density is about 6-7 orders of magnitude higher than in typical laboratory dusty plasmas, i.e. {approx}10{sup 22} m{sup -3}, and the ion temperature is a few eV. The plasma flows at speeds of the order of 20-60 km/s. Two observed features characterize dust in this new plasma regime: the plasma drag force dominates over all other forces acting on the grains and the microparticles are heated to temperatures sufficiently high, to become self-illuminated. Simultaneous observation at different moments in time of up to a few hundred flying dust grains has been possible due to the timing capabilities of a high-speed camera equipped with a telephoto lens. Dust speed of a few km/s and accelerations of {approx}10{sup 5}-10{sup 6} m/s{sup 2} have been inferred using the time-of-flight technique. Among the applications of hypervelocity dust are local diagnostics performed on hot plasmas, interstellar propulsion or simulation of meteorite impacts.

  12. Molecular Dynamics Simulation of Electron-Ion Temperature Relaxation in Dense Hydrogen: Electronic Quantum Effects

    NASA Astrophysics Data System (ADS)

    Ma, Qian; Dai, Jiayu; Zhao, Zengxiu

    2016-10-01

    The electron-ion temperature relaxation is an important non-equilibrium process in the generation of dense plasmas, particularly in Inertial Confinement Fusion. Classical molecular dynamics considers electrons as point charges, ignoring important quantum processes. We use an Electron Force Field (EFF) method to study the temperature relaxation processes, considering the nuclei as semi-classical point charges and assume electrons as Gaussian wave packets which includes the influences of the size and the radial motion of electrons. At the same time, a Pauli potential is used to describe the electronic exchange effect. At this stage, quantum effects such as exchange, tunneling can be included in this model. We compare the results from EFF and classical molecular dynamics, and find that the relaxation time is much longer with including quantum effects, which can be explained directly by the deference of collision cross sections between quantum particles and classical particles. Further, the final thermal temperature of electron and ion is different compared with classical results that the electron quantum effects cannot be neglected.

  13. Orbital-free molecular dynamics simulations of transport properties in dense-plasma uranium

    NASA Astrophysics Data System (ADS)

    Kress, J. D.; Cohen, James S.; Kilcrease, D. P.; Horner, D. A.; Collins, L. A.

    2011-09-01

    We have calculated the self-diffusion coefficients and shear viscosity of dense-plasma uranium using orbital-free molecular dynamics (OFMD) at the Thomas-Fermi-Dirac level. The transport properties of uranium in this regime have not previously been investigated experimentally or theoretically. The OFMD calculations were performed for temperatures from 50 to 5000 eV and densities from ambient to 10 times compressed. The results are compared with the one-component-plasma (OCP) model, using effective charges given by the average-atom code INFERNO and by the regularization procedure from the OFMD method. The latter generally showed better agreement with the OFMD for viscosity and the former for diffusion. A Stokes-Einstein relationship of the OFMD viscosities and diffusion coefficients is found to hold fairly well with a constant of 0.075 ± 0.10, while the OCP/INFERNO model yields 0.13 ± 0.10.

  14. D-D neutron yield in the 125 J dense plasma focus Nanofocus

    NASA Astrophysics Data System (ADS)

    Milanese, M.; Moroso, R.; Pouzo, J.

    2003-11-01

    We present here a very small transportable dense plasma focus with 125 J of energy able to be used mainly as an intense fast neutron source. The aim of this work was to design, construct and experimentally study a very compact nuclear fusion apparatus, at the lower energy limit, useful for multiple applications, such as soil humidity measurements, inspection of several materials metallic inclusions, medical neutron-therapies, etc. Besides, the possibility of using the same device as X-rays emitter has been explored. In a narrow range of deuterium filling pressure around 1 mbar, peaked Rogowski dips are observed. Correspondingly, strong neutron and hard X-ray pulses are measured. The neutron pulses last, in average, 50 ns, being about 106 the amount of neutrons per pulse. The performance of this device has shown to be higher than any other plasma focus apparatus, compar ed on the empirical scaling law of neutron yield vs. pinch current.

  15. Specific features of SRS-CARS monitoring of low impurity concentrations of hydrogen in dense gas mixtures

    NASA Astrophysics Data System (ADS)

    Mikheev, Gennady M.; Mogileva, Tatyana N.; Popov, Aleksey Yu.

    2006-09-01

    The possibility of measuring the hydrogen impurity concentration in dense gas mixtures by coherent anti-Stokes Raman scattering (CARS) is studied. In this technique, biharmonic laser pumping based on stimulated Raman scattering (SRS) in compressed hydrogen is used. Because of the interference between the coherent scattering components from buffer gas molecules and molecules of the impurity to be detected, the signal recorded may depend on the hydrogen concentration by a parabolic law, which has a minimum and makes the results uncertain. It is shown that this uncertainty can be removed if the frequency of the biharmonic laser pump, which is produced by the SRS oscillator, somewhat differs from the frequency of molecular oscillations of hydrogen in the test mixture. A sensitivity of 5 ppm is obtained as applied to the hydrogen-air mixture under normal pressure. The description of a set-up for the determination of the coefficient of the hydrogen diffusion in gas mixtures is given. The main assembly units are a diffusion chamber and an automated laser system for the selective hydrogen diagnostics in gas mixtures by the SRS-CARS method. The determination of the diffusion coefficient is based on the approximation of the experimental data describing the hydrogen concentration varying with time at a specified point in the diffusion chamber and the accurate solution of the diffusion equation for the selected one-dimensional geometry of the experiment.

  16. An experimental study of laser supported hydrogen plasmas

    NASA Technical Reports Server (NTRS)

    Vanzandt, D. M.; Mccay, T. D.; Eskridge, R. H.

    1984-01-01

    The rudiments of a rocket thruster which receives its enthalpy from an energy source which is remotely beamed from a laser is described. An experimental study now partially complete is discussed which will eventually provide a detailed understanding of the physics for assessing the feasibility of using hydrogen plasmas for accepting and converting this energy to enthalpy. A plasma ignition scheme which uses a pulsed CO2 laser has been developed and the properties of the ignition spark documented, including breakdown intensities in hydrogen. A complete diagnostic system capable of determining plasma temperature and the plasma absorptivity for subsequent steady state absorption of a high power CO2 laser beam are developed and demonstrative use is discussed for the preliminary case study, a two atmosphere laser supported argon plasma.

  17. Plasma-Surface Interactions of Hydrogenated Carbon

    DTIC Science & Technology

    2009-01-01

    with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1...rate of progress in the area of tritium re- moval, together with favorable results from divertor tokamaks with high atomic number (e.g. tungsten) walls...hydrogen ions and thermal atomic hydrogen, both for pure carbon as well as mixed materials systems . Properly bench- marked molecular dynamics (MD

  18. Large scale, highly dense nanoholes on metal surfaces by underwater laser assisted hydrogen etching near nanocrystalline boundary

    NASA Astrophysics Data System (ADS)

    Lin, Dong; Zhang, Martin Yi; Ye, Chang; Liu, Zhikun; Liu, C. Richard; Cheng, Gary J.

    2012-03-01

    A new method to generate large scale and highly dense nanoholes is presented in this paper. By the pulsed laser irradiation under water, the hydrogen etching is introduced to form high density nanoholes on the surfaces of AISI 4140 steel and Ti. In order to achieve higher nanohole density, laser shock peening (LSP) followed by recrystallization is used for grain refinement. It is found that the nanohole density does not increase until recrystallization of the substructures after laser shock peening. The mechanism of nanohole generation is studied in detail. This method can be also applied to generate nanoholes on other materials with hydrogen etching effect.

  19. Controlling the Neutron Yield from a Small Dense Plasma Focus using Deuterium-Inert Gas Mixtures

    SciTech Connect

    Bures, B. L.; Krishnan, M.; Eshaq, Y.

    2009-01-21

    The dense plasma focus (DPF) is a well known source of neutrons when operating with deuterium. The DPF is demonstrated to scale from 10{sup 4} n/pulse at 40 kA to >10{sup 12} n/pulse at 2 MA by non-linear current scaling as described in [1], which is itself based on the simple yet elegant model developed by Lee [2]. In addition to the peak current, the gas pressure controls the neutron yield. Recent published results suggest that mixing 1-5% mass fractions of Krypton increase the neutron yield per pulse by more than 10x. In this paper we present results obtained by mixing deuterium with Helium, Neon and Argon in a 500 J dense plasma focus operating at 140 kA with a 600 ns rise time. The mass density was held constant in these experiments at the optimum (pure) deuterium mass density for producing neutrons. A typical neutron yield for a pure deuterium gas charge is 2x10{sup 6}{+-}15% n/pulse. Neutron yields in excess of 10{sup 7}{+-}10% n/pulse were observed with low mass fractions of inert gas. Time integrated optical images of the pinch, soft x-ray measurements and optical emission spectroscopy where used to examine the pinch in addition to the neutron yield monitor and the fast scintillation detector. Work supported by Domestic Nuclear Detection Office under contract HSHQDC-08-C-00020.

  20. Runaway electrons as a source of impurity and reduced fusion yield in the dense plasma focus

    SciTech Connect

    Lerner, Eric J.; Yousefi, Hamid R.

    2014-10-15

    Impurities produced by the vaporization of metals in the electrodes may be a major cause of reduced fusion yields in high-current dense plasma focus devices. We propose here that a major, but hitherto-overlooked, cause of such impurities is vaporization by runaway electrons during the breakdown process at the beginning of the current pulse. This process is sufficient to account for the large amount of erosion observed in many dense plasma focus devices on the anode very near to the insulator. The erosion is expected to become worse with lower pressures, typical of machines with large electrode radii, and would explain the plateauing of fusion yield observed in such machines at higher peak currents. Such runaway electron vaporization can be eliminated by the proper choice of electrode material, by reducing electrode radii and thus increasing fill gas pressure, or by using pre-ionization to eliminate the large fields that create runaway electrons. If these steps are combined with monolithic electrodes to eliminate arcing erosion, large reductions in impurities and large increases in fusion yield may be obtained, as the I{sup 4} scaling is extended to higher currents.

  1. Radiography using a dense plasma focus device as a source of pulsed X-rays

    NASA Astrophysics Data System (ADS)

    Herrera, Julio; Castillo, Fermín; Gamboa, Isabel; Rangel, José

    2007-11-01

    Soft and hard X-ray emissions have been studied in the FN-II, which is a small dense plasma focus machine (5 kJ), operating at the Instituto de Ciencias Nucleares, UNAM, using aluminum filtered pin-hole cameras. Their angular distribution has been measured using TLD-200 dosimeters [1]. Their temporal evolution has been observed by means of a PIN diode, and scinltillators coupled to photomultipliers outside the discharge chamber. The X rays source can be concentrated by placing a needle on the end of the electrode. X-rays crossing across a 300 micron aluminum window, through the axis of the machine, can be used to obtain high contrast radiographs, with an average dose of 0.4 mGy per shot. In contrast, the average dose with a hollow cathode is 0.2 mGy per shot. This work is partially supported by grant IN105705 de la DGAPA-UNAM. [1] F. Castillo, J.J.E. Herrera, J. Rangel, I. Gamboa, G. Espinosa y J.I. Golzarri ``Angular Distribution of fusion products and X-rays emitted by a small dense plasma focus machine'' Journal of Applied Physics 101 013303-1-7 (2007).

  2. Kinetic Modeling of Ion Beams in Dense Plasma Focus Z-Pinches

    NASA Astrophysics Data System (ADS)

    Link, A.; Bennett, N.; Falabella, S.; Higginson, D. P.; Olsen, R.; Podpaly, Y. A.; Povilus, A.; Shaw, B.; Sipes, N.; Welch, D. R.; Schmidt, A.

    2016-10-01

    Dense plasma focus (DPF) Z-pinches are compact devices capable of producing MeV ion beams, x-rays, and (for D or DT gas fill) neutrons. We report on predictions of ion beam generation using the particle-in-cell code LSP. These simulations include full-scale electrodes, an external pulse power circuit and model through the run-down phase as a fluid, transitioning to a fully kinetic simulation during the run-in phase and through the pinch. Simulations of a deuterium filled DPF predict a substantial number of ions accelerated to energies greater than 50 keV escape the dense plasma in the pinch region and could be used to enhance total neutron yield by employing a solid target. Results of the simulations will be presented and compared to experimental observations. LLNL-ABS-697617 This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344 and with support from the Computing Grand Challenge program at LLNL.

  3. High Power Ion Heating in Helium and Hydrogen Plasmas for Advanced Plasma Thrusters

    NASA Astrophysics Data System (ADS)

    Ando, Akira; Hagiwara, Tatsuya; Domon, Masakazu; Taguchi, Takahiro

    High power ion cyclotron resonance heating is performed in a fast-flowing plasma operated with hydrogen and helium gases. Ion heating is clearly observed in hydrogen plasma as well as in helium plasma. The resonance region of magnetic field is broader and wave absorption efficiency is higher in hydrogen plasma than those in helium plasma. The thermal energy of the heated ions is converted to the kinetic energy of the exhaust plume by passing through a diverging magnetic nozzle set in a downstream region. In the magnetic nozzle energy conversion occurred as keeping the magnetic moment constant, but some discrepancy was observed in larger gradient of magnetic field. The kinetic energy of the exhaust plume is successfully controlled by an input power of radio-frequency wave, which is one of the key technologies for the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) type plasma thruster.

  4. Simulation of thermal ionization in a dense helium plasma by the Feynman path integral method

    NASA Astrophysics Data System (ADS)

    Shevkunov, S. V.

    2011-04-01

    The region of equilibrium states is studied where the quantum nature of the electron component and a strong nonideality of a plasma play a key role. The problem of negative signs in the calculation of equilibrium averages a system of indistinguishable quantum particles with a spin is solved in the macroscopic limit. It is demonstrated that the calculation can be conducted up to a numerical result. The complete set of symmetrized basis wave functions is constructed based on the Young symmetry operators. The combinatorial weight coefficients of the states corresponding to different graphs of connected Feynman paths in multiparticle systems are calculated by the method of random walk over permutation classes. The kinetic energy is calculated using a viral estimator at a finite pressure in a statistical ensemble with flexible boundaries. Based on the methods developed in the paper, the computer simulation is performed for a dense helium plasma in the temperature range from 30000 to 40000 K. The equation of state, internal energy, ionization degree, and structural characteristic of the plasma are calculated in terms of spatial correlation functions. The parameters of a pseudopotential plasma model are estimated.

  5. Comparisons of dense-plasma-focus kinetic simulations with experimental measurements

    SciTech Connect

    Schmidt, A.; Link, A.; Welch, D.; Ellsworth, J.; Falabella, S.; Tang, V.

    2014-06-01

    Dense-plasma-focus (DPF) Z-pinch devices are sources of copious high-energy electrons and ions, x rays, and neutrons. The mechanisms through which these physically simple devices generate such high-energy beams in a relatively short distance are not fully understood and past optimization efforts of these devices have been largely empirical. Previously we reported on fully kinetic simulations of a DPF and compared them with hybrid and fluid simulations of the same device. Here we present detailed comparisons between fully kinetic simulations and experimental data on a 1.2 kJ DPF with two electrode geometries, including neutron yield and ion beam energy distributions. A more intensive third calculation is presented which examines the effects of a fully detailed pulsed power driver model. We also compare simulated electromagnetic fluctuations with direct measurement of radiofrequency electromagnetic fluctuations in a DPF plasma. These comparisons indicate that the fully kinetic model captures the essential physics of these plasmas with high fidelity, and provide further evidence that anomalous resistivity in the plasma arises due to a kinetic instability near the lower hybrid frequency.

  6. Runaway electron production during intense electron beam penetration in dense plasma

    SciTech Connect

    Parks, P. B.; Cowan, T. E.

    2007-01-15

    Relativistic electrons are efficiently generated when multiterawatt lasers focused to ultrahigh intensities > or approx. 10{sup 19} W/cm{sup 2} illuminate the surface of dense plasma targets. A theoretical study finds that during typical picosecond pulse widths, significant amounts of Dreicer produced runaway electrons can build up due to the high axial electric field driving the neutralizing return current. An important consequence is that there will be a conversion of plasma current to runaway electron current, which is maximized at some optimum value of the beam-to-plasma density ratio N{sub b}=n{sub b}/n{sub e}, depending on the plasma collisionality. At collisionalities representative of solid target experiments, complete conversion to runaway electrons can only take place over a certain range of N{sub b} values. At higher collisionalities and pulse widths, applicable to the fast ignition concept for inertial confinement fusion, it was found that conversion to runaways has a peak at {approx}90% around N{sub b}{approx}0.06. Significant lessening of target material heating by Joule current dissipation is also possible, since part of the beam energy loss is transferred through the electric field directly to the formation of energetic runaways. Implications for beam transport inhibition by the electric field are also discussed.

  7. Hydrogen desorption from hydrogen fluoride and remote hydrogen plasma cleaned silicon carbide (0001) surfaces

    SciTech Connect

    King, Sean W. Tanaka, Satoru; Davis, Robert F.; Nemanich, Robert J.

    2015-09-15

    Due to the extreme chemical inertness of silicon carbide (SiC), in-situ thermal desorption is commonly utilized as a means to remove surface contamination prior to initiating critical semiconductor processing steps such as epitaxy, gate dielectric formation, and contact metallization. In-situ thermal desorption and silicon sublimation has also recently become a popular method for epitaxial growth of mono and few layer graphene. Accordingly, numerous thermal desorption experiments of various processed silicon carbide surfaces have been performed, but have ignored the presence of hydrogen, which is ubiquitous throughout semiconductor processing. In this regard, the authors have performed a combined temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) investigation of the desorption of molecular hydrogen (H{sub 2}) and various other oxygen, carbon, and fluorine related species from ex-situ aqueous hydrogen fluoride (HF) and in-situ remote hydrogen plasma cleaned 6H-SiC (0001) surfaces. Using XPS, the authors observed that temperatures on the order of 700–1000 °C are needed to fully desorb C-H, C-O and Si-O species from these surfaces. However, using TPD, the authors observed H{sub 2} desorption at both lower temperatures (200–550 °C) as well as higher temperatures (>700 °C). The low temperature H{sub 2} desorption was deconvoluted into multiple desorption states that, based on similarities to H{sub 2} desorption from Si (111), were attributed to silicon mono, di, and trihydride surface species as well as hydrogen trapped by subsurface defects, steps, or dopants. The higher temperature H{sub 2} desorption was similarly attributed to H{sub 2} evolved from surface O-H groups at ∼750 °C as well as the liberation of H{sub 2} during Si-O desorption at temperatures >800 °C. These results indicate that while ex-situ aqueous HF processed 6H-SiC (0001) surfaces annealed at <700 °C remain terminated by some surface C–O and

  8. Hydrogen Evolution by Plasma Electrolysis in Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Mizuno, Tadahiko; Akimoto, Tadashi; Azumi, Kazuhisa; Ohmori, Tadayoshi; Aoki, Yoshiaki; Takahashi, Akito

    2005-01-01

    Hydrogen has recently attracted attention as a possible solution to environmental and energy problems. If hydrogen should be considered an energy storage medium rather than a natural resource. However, free hydrogen does not exist on earth. Many techniques for obtaining hydrogen have been proposed. It can be reformulated from conventional hydrocarbon fuels, or obtained directly from water by electrolysis or high-temperature pyrolysis with a heat source such as a nuclear reactor. However, the efficiencies of these methods are low. The direct heating of water to sufficiently high temperatures for sustaining pyrolysis is very difficult. Pyrolysis occurs when the temperature exceeds 4000°C. Thus plasma electrolysis may be a better alternative, it is not only easier to achieve than direct heating, but also appears to produce more hydrogen than ordinary electrolysis, as predicted by Faraday’s laws, which is indirect evidence that it produces very high temperatures. We also observed large amounts of free oxygen generated at the cathode, which is further evidence of direct decomposition, rather than electrolytic decomposition. To achieve the continuous generation of hydrogen with efficiencies exceeding Faraday efficiency, it is necessary to control the surface conditions of the electrode, plasma electrolysis temperature, current density and input voltage. The minimum input voltage required induce the plasma state depends on the density and temperature of the solution, it was estimated as 120 V in this study. The lowest electrolyte temperature at which plasma forms is ˜75°C. We have observed as much as 80 times more hydrogen generated by plasma electrolysis than by conventional electrolysis at 300 V.

  9. Plasma promoted manufacturing of hydrogen and vehicular applications

    NASA Astrophysics Data System (ADS)

    Bromberg, Leslie

    2003-10-01

    Plasmas can be used for promoting reformation of fuels. Plasma-based reformers developed at MIT use a low temperature, low power, low current electrical discharge to promote partial oxidation conversion of hydrocarbon fuels into hydrogen and CO. The very fuel rich mixture is hard to ignite, and the plasmatron provides a volume-ignition. To minimize erosion and to simplify the power supply, a low current high voltage discharge is used, with wide area electrodes. The plasmatron fuel reformer operates at or slightly above atmospheric pressure. The plasma-based reformer technology provides the advantages of rapid startup and transient response; efficient conversion of the fuel to hydrogen rich gas; compact size; relaxation or elimination of reformer catalyst requirements; and capability to process difficult to reform fuels. These advantages enable use of hydrogen-manufacturing reformation technology in cars using available fuels, such as gasoline and diesel. This plasma-based reformer technology can provide substantial throughputs even without the use of a catalyst. The electrical power consumption of the device is minimized by design and operational characteristics (less than 500 W peak and 200 W average). The product from these plasma reactors is a hydrogen rich mixture that can be used for combustion enhancement and emissions aftertreatment in vehicular applications. By converting a small fraction of the fuel to hydrogen rich gas, in-cylinder combustion can be improved. With minor modification of the engine, use of hydrogen rich gas results in increased fuel efficiency and decreased emissions of smog producing gases. The status of plasma based reformer technology and its application to vehicles will be described.

  10. Energy relaxation and the quasiequation of state of a dense two-temperature nonequilibrium plasma

    NASA Astrophysics Data System (ADS)

    Dharma-Wardana, M. W. C.; Perrot, François

    1998-09-01

    A first principles approach to the equation of state (EOS) and the transport properties of an interacting mixture of electrons, ions, and neutrals in thermodynamic equilibrium was presented recently in Phys. Rev. E 52, 5352 (1995). However, many dynamically produced plasmas have an electron temperature Te different from the ion temperature Ti. The study of these nonequilibrium (non-eq.) systems involves (i) calculation of a quasiequation of state (quasi-EOS) and the needed non-eq. correlation functions, e.g., the dynamic structure factors Sss'(k,ω), where s is the species index; and (ii) a calculation of relaxation processes. The energy and momentum relaxations are usually described in terms of coupling constants determining the rates of equilibriation. Simple Spitzer-type calculations of such coupling constants often use formulas obtained by averaging the damping of a single energetic particle by the medium. However, a different result is obtained for the energy-loss rate of the electron subsystem when calculated from the commutator mean value <[He,H]->, where He and H are the Hamiltonians of the electron subsystem and the total system. This result corresponds to energy relaxation via the interaction of the normal modes of the hot system with the normal modes of the cold system. Such a description is particularly appropriate for dense plasmas. The evaluation of the commutator mean values within the Fermi golden rule (FGR), or more sophisticated Keldysh or Zubarev methods, yields formulations involving the dynamic structure factors of the two subsystems. The single-particle and normal-mode methods are conceptually very different. Here we present calculations of the energy relaxation of dense uniform two-temperature aluminum plasmas, and compare the usual Spitzer-type estimates with our more detailed FGR-type results. Our results show that the relaxation rate is more than an order of magnitude smaller than that given by the commonly used theories.

  11. The application of selected radionuclides for monitoring of the D-D reactions produced by dense plasma-focus device.

    PubMed

    Jednorog, S; Szydlowski, A; Bienkowska, B; Prokopowicz, R

    The dense plasma focus (DPF) device-DPF-1000U which is operated at the Institute of Plasma Physics and Laser Microfusion is the largest that type plasma experiment in the world. The plasma that is formed in large plasma experiments is characterized by vast numbers of parameters. All of them need to be monitored. A neutron activation method occupies a high position among others plasma diagnostic methods. The above method is off-line, remote, and an integrated one. The plasma which has enough temperature to bring about nuclear fusion reactions is always a strong source of neutrons that leave the reactions area and take along energy and important information on plasma parameters and properties as well. Silver as activated material is used as an effective way of neutrons measurement, especially when they are emitted in the form of short pulses like as it happens from the plasma produced in Dense Plasma-Focus devices. Other elements such as beryllium and yttrium are newly introduced and currently tested at the Institute of Plasma Physics and Laser Microfusion to use them in suitable activation neutron detectors. Some specially designed massive indium samples have been recently adopted for angular neutrons distribution measurements (vertical and horizontal) and have been used in the recent plasma experiment conducted on the DPF-1000U device. This choice was substantiated by relatively long half-lives of the neutron induced isotopes and the threshold character of the (115)In(n,n')(115m)In nuclear reaction.

  12. Effect of driver impedance on dense plasma focus Z-pinch neutron yield

    SciTech Connect

    Sears, Jason E-mail: schmidt36@llnl.gov; Link, Anthony E-mail: schmidt36@llnl.gov; Schmidt, Andrea E-mail: schmidt36@llnl.gov; Welch, Dale

    2014-12-15

    The Z-pinch phase of a dense plasma focus (DPF) heats the plasma by rapid compression and accelerates ions across its intense electric fields, producing neutrons through both thermonuclear and beam-target fusion. Driver characteristics have empirically been shown to affect performance, as measured by neutron yield per unit of stored energy. We are exploring the effect of driver characteristics on DPF performance using particle-in-cell (PIC) simulations of a kJ scale DPF. In this work, our PIC simulations are fluid for the run-down phase and transition to fully kinetic for the pinch phase, capturing kinetic instabilities, anomalous resistivity, and beam formation during the pinch. The anode-cathode boundary is driven by a circuit model of the capacitive driver, including system inductance, the load of the railgap switches, the guard resistors, and the coaxial transmission line parameters. It is known that the driver impedance plays an important role in the neutron yield: first, it sets the peak current achieved at pinch time; and second, it affects how much current continues to flow through the pinch when the pinch inductance and resistance suddenly increase. Here we show from fully kinetic simulations how total neutron yield depends on the impedance of the driver and the distributed parameters of the transmission circuit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for neutron source applications.

  13. Dense plasma heating and Gbar shock formation by a high intensity flux of energetic electrons

    SciTech Connect

    Ribeyre, X.; Feugeas, J.-L.; Nicolaï, Ph.; Tikhonchuk, V. T.; Gus'kov, S.

    2013-06-15

    Process of shock ignition in inertial confinement fusion implies creation of a high pressure shock with a laser spike having intensity of the order of a few PW/cm{sup 2}. However, the collisional (Bremsstrahlung) absorption at these intensities is inefficient and a significant part of laser energy is converted in a stream of energetic electrons. The process of shock formation in a dense plasma by an intense electron beam is studied in this paper in a planar geometry. The energy deposition takes place in a fixed mass target layer with the areal density determined by the electron range. A self-similar isothermal rarefaction wave of a fixed mass describes the expanding plasma. Formation of a shock wave in the target under the pressure of expanding plasma is described. The efficiency of electron beam energy conversion into the shock wave energy depends on the fast electron energy and the pulse duration. The model is applied to the laser produced fast electrons. The fast electron energy transport could be the dominant mechanism of ablation pressure creation under the conditions of shock ignition. The shock wave pressure exceeding 1 Gbar during 200–300 ps can be generated with the electron pulse intensity in the range of 5–10 PW/cm{sup 2}. The conclusions of theoretical model are confirmed in numerical simulations with a radiation hydrodynamic code coupled with a fast electron transport module.

  14. Effect of Anode Impurity on the Neutron Production in a Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Yousefi, H. R.; Masugata, K.

    2011-12-01

    In this study, neutron production characteristics were investigated by employing three different anode designs. Previously, Takao et al. in Plasma Sour Sci Technol 12:407, (2003) studied the effect of anode design on the production of impurity ions in a dense plasma focus (DPF) device. It was found that rod type anodes led to large quantities of impurity ions, resulting in an ion purity of only 25%. In contrast, in hollow type anodes the quantities of impurity ions is strongly reduced, resulting in an enhanced ion purity of 91%. These impurities in the DPF system originate partly from residual gas in the vacuum system, but also from vaporization of the anode, which produces metallic ions such as copper. In the present work, we extend previous investigations Takao et al. in Plasma Sour Sci Technol 12:407, (2003) of the effects of anode shape (A—long hollow, B—short hollow and C—rod type) on neutron production. Here we focus specifically on the effects of anode impurity on neutron production. It was found that in anode type C, the neutron intensity and neutron yield is lower than in type A or B.

  15. Large-scale molecular dynamics simulations of dense plasmas: The Cimarron Project

    NASA Astrophysics Data System (ADS)

    Graziani, Frank R.; Batista, Victor S.; Benedict, Lorin X.; Castor, John I.; Chen, Hui; Chen, Sophia N.; Fichtl, Chris A.; Glosli, James N.; Grabowski, Paul E.; Graf, Alexander T.; Hau-Riege, Stefan P.; Hazi, Andrew U.; Khairallah, Saad A.; Krauss, Liam; Langdon, A. Bruce; London, Richard A.; Markmann, Andreas; Murillo, Michael S.; Richards, David F.; Scott, Howard A.; Shepherd, Ronnie; Stanton, Liam G.; Streitz, Fred H.; Surh, Michael P.; Weisheit, Jon C.; Whitley, Heather D.

    2012-03-01

    We describe the status of a new time-dependent simulation capability for dense plasmas. The backbone of this multi-institutional effort - the Cimarron Project - is the massively parallel molecular dynamics (MD) code "ddcMD," developed at Lawrence Livermore National Laboratory. The project's focus is material conditions such as exist in inertial confinement fusion experiments, and in many stellar interiors: high temperatures, high densities, significant electromagnetic fields, mixtures of high- and low- Z elements, and non-Maxwellian particle distributions. Of particular importance is our ability to incorporate into this classical MD code key atomic, radiative, and nuclear processes, so that their interacting effects under non-ideal plasma conditions can be investigated. This paper summarizes progress in computational methodology, discusses strengths and weaknesses of quantum statistical potentials as effective interactions for MD, explains the model used for quantum events possibly occurring in a collision, describes two new experimental efforts that play a central role in our validation work, highlights some significant results obtained to date, outlines concepts now being explored to deal more efficiently with the very disparate dynamical timescales that arise in fusion plasmas, and provides a careful comparison of quantum effects on electron trajectories predicted by more elaborate dynamical methods.

  16. AmBe Radiological Source Replacement Using Dense Plasma Focus Z-Pinch

    NASA Astrophysics Data System (ADS)

    Shaw, Brian; Povilus, Alexander; Chapman, Steven; Podpaly, Yuri; Cooper, Christopher; Higginson, Drew; Link, Anthony; Schmidt, Andrea

    2016-10-01

    A dense plasma focus (DPF) is a compact plasma gun that produces high energy ion beams up to several MeV through strong potential gradients formed from m=0 plasma instabilities. These ion beams can be used to replace radiological sources for a variety of applications. Americium-beryllium (AmBe) neutron sources are commonly used for oil well logging. An optimized DPF produces high energy helium ion beams of 2+ MeV which can interact with a beryllium target to produce neutrons. The alpha-Be interaction produces a neutron energy spectrum similar to the neutrons produced by the AmBe reaction. To demonstrate this concept experimentally a 2 kJ DPF is used to produce a beam of alpha particles which interacts with a beryllium target. We report on the improvements made to the DPF platform using He gas and the observation of 3.0 ×104 peak neutrons generated per shot. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Development of the dense plasma focus for short-pulse applications

    DOE PAGES

    Bennett, N.; Blasco, M.; Breeding, K.; ...

    2017-01-05

    The dense plasma focus (DPF) has long been considered a compact source for pulsed neutrons and has traditionally been optimized for the total neutron yield. Here, we describe the efforts to optimize the DPF for short-pulse applications by introducing a reentrant cathode at the end of the coaxial plasma gun. We reduced the resulting neutron pulse widths by an average of 21±921±9% from the traditional long-drift DPF design. Pulse widths and yields achieved from deuterium-tritium fusion at 2 MA are 61.8±30.761.8±30.7 ns FWHM and 1.84±0.49×10121.84±0.49×1012 neutrons per shot. Simulations were conducted concurrently to elucidate the DPF operation and confirm themore » role of the reentrant cathode. Furthermore, a hybrid fluid-kinetic particle-in-cell modeling capability demonstrates correct sheath velocities, plasma instabilities, and fusion yield rates. Consistent with previous findings that the DPF is dominated by beam-target fusion from superthermal ions, we estimate that the thermonuclear contribution is at the 1% level.« less

  18. Construction of a Compact, Low-Inductance, 100 J Dense Plasma Focus for Yield Optimization Studies

    NASA Astrophysics Data System (ADS)

    Cooper, Christopher; Povilus, Alex; Chapman, Steven; Falabella, Steve; Podpaly, Yuri; Shaw, Brian; Liu, Jason; Schmidt, Andrea

    2016-10-01

    A new 100 J mini dense plasma focus (DPF) is constructed to optimize neutron yields for a variety of plasma conditions and anode shapes. The device generates neutrons by leveraging instabilities that occur during a z-pinch in a plasma sheath to accelerate a beam of deuterium ions into a background deuterium gas target. The features that distinguish this miniDPF from previous 100 J devices are a compact, engineered electrode geometry and a low-impedance driver. The driving circuit inductance is minimized by mounting the capacitors close to the back of the anode and cathode < 20 cm away, increasing the breakdown current and yields. The anode can rapidly be changed out to test new designs. The neutron yield and 2D images of the visible light emission are compared to simulations with the hybrid kinetic code LSP which can directly simulate the device and anode designs. Initial studies of the sheath physics and neutron yields for a scaling of discharge voltages and neutral fill pressures are presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  19. Nonlinear Absorption of X-ray Free Electron Laser Pulses in Dense Aluminum Plasmas

    NASA Astrophysics Data System (ADS)

    Cho, Min Sang; Kim, M.; Chung, H.-K.; Cho, Byoung-Ick

    2016-10-01

    XFEL provides unique opportunities to generate and investigate dense plasmas. Here, we present the intensity dependent, nonlinear x-ray absorption in dense aluminum target using the collisional-radiative population kinetic calculations. With high peak intensity of XFEL pulses, even below K-absorption edge, x-ray photons could create excited states of which absorption is larger than the ground state absorption. At the resonant energy of neutral atom, increasing x-ray absorption in the intensity range of 1016 17 W/cm2 has been observed, and it is the reverse saturable absorption in the x-ray regime. The similar observations have been also made at the other resonant energies of higher charge states. At even higher XFEL intensities, bleaching a specific charge state could lead a transition from reverse saturable absorption to saturable absorption, so thus x-ray absorption is decreasing. Detailed population kinetics of charge states relevant to the absorption of x-ray photons, and fast modulation of XFEL spectrum will be discussed. This work is supported by Institute of Basic Science (IBS-R012-D1) and National Research Foundation of Korea (No. 2015R1A5A1009962 and 2016R1A2B4009631).

  20. Ion beam and neutron output from a sub-kilojoule dense plasma focus

    SciTech Connect

    Ellsworth, J. L. Falabella, S. Schmidt, A. Tang, V.

    2014-12-15

    We are seeking to gain a better fundamental understanding of the ion beam acceleration and neutron production dense plasma focus (DPF) device. Experiments were performed on a kilojoule level, fast rise time DPF located at LLNL. Ion beam spectra and neutron yield were measured for deuterium pinches. Visible light images of the pinch are used to determine the pinch length. In addition, an RF probe was placed just outside the cathode to measure fluctuations in E{sub z} up to 6 GHz, which is within the range of the lower hybrid frequencies. We find these oscillations arise at a characteristic frequency near 4 GHz during the pinch. Comparisons of the neutron yield and ion beam characteristics are presented. The neutron yield is also compared to scaling laws.

  1. Megagauss magnetic fields in ultra-intense laser generated dense plasmas

    NASA Astrophysics Data System (ADS)

    Shaikh, Moniruzzaman; Lad, Amit D.; Jana, Kamalesh; Sarkar, Deep; Dey, Indranuj; Kumar, G. Ravindra

    2017-01-01

    Table-top terawatt lasers can create relativistic light intensities and launch megaampere electron pulses in a solid. These pulses induce megagauss (MG) magnetic pulses, which in turn strongly affect the hot electron transport via electromagnetic instabilities. It is therefore crucial to characterize the MG magnetic fields in great detail. Here, we present measurements of the spatio-temporal evolution of MG magnetic fields produced by a high contrast (picosecond intensity contrast 10-9) laser in a dense plasma on a solid target. The MG magnetic field is measured using the magneto-optic Cotton-Mouton effect, with a time delayed second harmonic (400 nm) probe. The magnetic pulse created by the high contrast laser in a glass target peaks much faster and has a more rapid fall than that induced by a low contrast (10-6) laser.

  2. Design of Z-Pinch and Dense Plasma Focus Powered Vehicles

    NASA Technical Reports Server (NTRS)

    Polsgrove, Tara; Fincher, Sharon; Adams, Robert B.; Cassibry, Jason; Cortez, Ross; Turner, Matthew; Maples, C. Daphne; Miermik, Janie N.; Statham, Geoffrey N.; Fabisinski, Leo; Santarius, John; Percy, Tom

    2011-01-01

    Z-pinch and Dense Plasma Focus (DPF) are two promising techniques for bringing fusion power to the field of in-space propulsion. A design team comprising of engineers and scientists from UAHuntsville, NASA's George C. Marshall Space Flight Center and the University of Wisconsin developed concept vehicles for a crewed round trip mission to Mars and an interstellar precursor mission. Outlined in this paper are vehicle concepts, complete with conceptual analysis of the mission profile, operations, structural and thermal analysis and power/avionics design. Additionally engineering design of the thruster itself is included. The design efforts adds greatly to the fidelity of estimates for power density (alpha) and overall performance for these thruster concepts

  3. Influence of optical non-uniformity on the reflectance of dense plasmas

    NASA Astrophysics Data System (ADS)

    Norman, G. E.; Saitov, I. M.

    2016-11-01

    We provide theoretical analysis of the reflectance of shock compressed plasmas and warm dense matter for normal incidence of laser radiation as well as for the dependence of s- and p-polarized reflectivity on incidence angle. We use density functional theory approach for the calculation of the dielectric function and reflectivity. The Kohn-Sham set of equations with the projector augmented wave (PAW) potential is solved for valent electrons. Due to the nonlocality of the PAW potentials, the longitudinal expression for the imaginary dielectric function is used. The real part is obtained by the Kramers-Kronig transformation. Quantum molecular dynamics simulation and VASP is used. Comparison with the experimental data for shock compressed xenon is performed. Three wavelengths are considered.

  4. Synthesis of dense yttrium-stabilised hafnia pellets for nuclear applications by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Tyrpekl, Vaclav; Holzhäuser, Michael; Hein, Herwin; Vigier, Jean-Francois; Somers, Joseph; Svora, Petr

    2014-11-01

    Dense yttrium-stabilised hafnia pellets (91.35 wt.% HfO2 and 8.65 wt.% Y2O3) were prepared by spark plasma sintering consolidation of micro-beads synthesised by the “external gelation” sol-gel technique. This technique allows a preparation of HfO2-Y2O3 beads with homogenous yttria-hafnia solid solution. A sintering time of 5 min at 1600 °C was sufficient to produce high density pellets (over 90% of the theoretical density) with significant reproducibility. The pellets have been machined in a lathe to the correct dimensions for use as neutron absorbers in an experimental test irradiation in the High Flux Reactor (HFR) in Petten, Holland, in order to investigate the safety of americium based nuclear fuels.

  5. An Investigation of Bremsstrahlung Reflection in a Dense Plasma Focus (DPF) Propulsion Device

    SciTech Connect

    Thomas, Robert; Miley, G. H.; Mead, Franklin

    2006-01-20

    The dense plasma focus device is one of the few fusion systems that is capable of burning advanced fuels such as D - 3He and p - 11B. An study has been performed and shown that three main requirements must be satisfied to reach breakeven for DPF fusion: a high Ti/Te ration ({approx} 20), an order of magnitude higher pinch lifetime, and the reflection and absorption if at least 50% Bremsstrahlung radiation. The latter issue is the focus of this report, and a literature search has been performed on laser-driven fusion radiation cavities, multilayer reflectors, and their application to Bremsstrahlung radiation reflection is presented. Additionally, the results found are compared to those assumed in the earlier DPF study bring p-11B.

  6. Phase transition of the baryon-antibaryon plasma in hot and dense nuclear matter

    NASA Astrophysics Data System (ADS)

    Lavagno, A.; Iazzi, F.; Pigato, D.

    2014-02-01

    We investigate the presence of thermodynamic instabilities in a hot and dense nuclear medium where a phase transition from a gas of massive hadrons to a nearly massless baryon, antibaryon plasma can take place. The analysis is performed by requiring the global conservation of baryon number and zero net strangeness in the framework of an effective relativistic mean field theory with the inclusion of the Δ(1232)-isobars, hyperons and the lightest pseudoscalar and vector meson degrees of freedom. Similarly to the low density nuclear liquid-gas phase transition, we show that such a phase transition is characterized by both mechanical instability (fluctuations on the baryon density) that by chemical- diffusive instability (fluctuations on the strangeness concentration). It turns out that, in this situation, phases with different values of antibaryon-baryon ratios and strangeness content may coexist.

  7. Negative hydrogen ion yields at plasma grid surface in a negative hydrogen ion source

    SciTech Connect

    Wada, M.; Kenmotsu, T.; Sasao, M.

    2015-04-08

    Negative hydrogen (H{sup −}) ion yield from the plasma grid due to incident hydrogen ions and neutrals has been evaluated with the surface collision cascade model, ACAT (Atomic Collision in Amorphous Target) coupled to a negative surface ionization models. Dependence of negative ion fractions upon the velocity component normal to the surface largely affect the calculation results of the final energy and angular distributions of the H{sup −} ions. The influence is particularly large for H{sup −} ions desorbed from the surface due to less than several eV hydrogen particle implact. The present calculation predicts that H{sup −} ion yield can be maximized by setting the incident angle of hydrogen ions and neutrals to be 65 degree. The Cs thickness on the plasma grid should also affect the yields and mean energies of surface produced H{sup −} ions by back scattering and ion induced desorption processes.

  8. Negative hydrogen ion yields at plasma grid surface in a negative hydrogen ion source

    NASA Astrophysics Data System (ADS)

    Wada, M.; Kenmotsu, T.; Sasao, M.

    2015-04-01

    Negative hydrogen (H-) ion yield from the plasma grid due to incident hydrogen ions and neutrals has been evaluated with the surface collision cascade model, ACAT (Atomic Collision in Amorphous Target) coupled to a negative surface ionization models. Dependence of negative ion fractions upon the velocity component normal to the surface largely affect the calculation results of the final energy and angular distributions of the H- ions. The influence is particularly large for H- ions desorbed from the surface due to less than several eV hydrogen particle implact. The present calculation predicts that H- ion yield can be maximized by setting the incident angle of hydrogen ions and neutrals to be 65 degree. The Cs thickness on the plasma grid should also affect the yields and mean energies of surface produced H- ions by back scattering and ion induced desorption processes.

  9. Dense Plasma Focus With High Energy Helium Beams for Radiological Source Replacement

    NASA Astrophysics Data System (ADS)

    Schmidt, Andrea; Ellsworth, Jennifer; Falabella, Steve; Link, Anthony; Rusnak, Brian; Sears, Jason; Tang, Vincent

    2014-10-01

    A dense plasma focus (DPF) is a compact accelerator that can produce intense high energy ion beams (multiple MeV). It could be used in place of americium-beryllium (AmBe) neutron sources in applications such as oil well logging if optimized to produce high energy helium beams. AmBe sources produce neutrons when 5.5 MeV alphas emitted from the Am interact with the Be. However, due to the very small alpha-Be cross section for alphas <2 MeV, an AmBe source replacement would have to accelerate ~0.15 μC of He to 2 + MeV in order to produce 107 neutrons per pulse. We are using our particle in cell (PIC) model in LSP of a 4 kJ dense plasma focus discharge to guide the optimization of a compact DPF for the production of high-energy helium beam. This model is fluid for the run-down phase, and then transitions to fully kinetic prior to the pinch in order to include kinetic effects such as ion beam formation and anomalous resistivity. An external pulsed-power driver circuit is used at the anode-cathode boundary. Simulations will be benchmarked to He beam measurements using filtered and time-of-flight Faraday cup diagnostics. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work supported by US DOE/NA-22 Office of Non-proliferation Research and Development. Computing support for this work came from the LLNL Institutional Computing Grand Challenge program.

  10. Coupled multigroup cross sections for hydrogen interactions in plasmas

    NASA Astrophysics Data System (ADS)

    Wienke, B. R.; Morel, J. E.; Cayton, T. E.; Howell, R. B.

    1985-10-01

    Using analytical fits to the experimental cross sections for H 3 H 2, and H 2+ interactions in plasmas, developed by Gryzinski, Riviere, Jones, and Freeman, we obtain coupled multigroup cross sections and rate coefficients for hydrogen transport applications. Multigroup cross sections and rate coefficients, for specified energy group boundaries, plasma particle and temperature profiles, and cylindrical plasma confinement radius, are generated against a spatially dependent, local Maxwellian scattering background. Cross sections are formatted for direct use in production multigroup S n, Monte Carlo, or specific transport applications. Ten coupled hydrogen reactions are included and resulting cross sections for ionization, scattering, and production can be coupled or decoupled. Reactions treated include H, H 2 ionization by electrons and protons, H, H 2 charge exchange, and H 2, H 2+ dissociative mechanisms. We detail the formalism used to compute effective cross sections and rates and give practicle results for two fusion reactors.

  11. Two-temperature modeling of laser sustained hydrogen plasmas

    NASA Astrophysics Data System (ADS)

    Mertogul, Ayhan E.; Krier, Herman

    1994-10-01

    A kinetic nonequilibrium model of laser sustained hydrogen plasmas has been formulated and solved for the prediction of steady-state energy transport processes. This model is the first of its kind and includes a discretized beam ray-trace with a variable index of refraction based upon plasma electron number density for a 10.6-micron CO2 laser input. Model results for fraction of incident laser power absorbed, and fraction of incident laser power retained by the hydrogen gas have compared favorably with experimental results. The model has been used to provide predictions of laser sustained plasma (LSP) performance well outside the realm of experiments to incident powers as high as 700 kW. At the gas pressures studied, minimal kinetic nonequilibrium was observed in LSP core regions, even for 700-kW laser power.

  12. Charge transfer in proton-hydrogen collisions under Debye plasma

    SciTech Connect

    Bhattacharya, Arka; Kamali, M. Z. M.; Ghoshal, Arijit; Ratnavelu, K.

    2015-02-15

    The effect of plasma environment on the 1s → nlm charge transfer, for arbitrary n, l, and m, in proton-hydrogen collisions has been investigated within the framework of a distorted wave approximation. The effect of external plasma has been incorporated using Debye screening model of the interacting charge particles. Making use of a simple variationally determined hydrogenic wave function, it has been possible to obtain the scattering amplitude in closed form. A detailed study has been made to investigate the effect of external plasma environment on the differential and total cross sections for electron capture into different angular momentum states for the incident energy in the range of 20–1000 keV. For the unscreened case, our results are in close agreement with some of the most accurate results available in the literature.

  13. Analysis of laser shock experiments on precompressed samples using a quartz reference and application to warm dense hydrogen and helium

    NASA Astrophysics Data System (ADS)

    Brygoo, Stephanie; Millot, Marius; Loubeyre, Paul; Lazicki, Amy E.; Hamel, Sebastien; Qi, Tingting; Celliers, Peter M.; Coppari, Federica; Eggert, Jon H.; Fratanduono, Dayne E.; Hicks, Damien G.; Rygg, J. Ryan; Smith, Raymond F.; Swift, Damian C.; Collins, Gilbert W.; Jeanloz, Raymond

    2015-11-01

    Megabar (1 Mbar = 100 GPa) laser shocks on precompressed samples allow reaching unprecedented high densities and moderately high ˜103-104 K temperatures. We describe here a complete analysis framework for the velocimetry (VISAR) and pyrometry (SOP) data produced in these experiments. Since the precompression increases the initial density of both the sample of interest and the quartz reference for pressure-density, reflectivity, and temperature measurements, we describe analytical corrections based on available experimental data on warm dense silica and density-functional-theory based molecular dynamics computer simulations. Using our improved analysis framework, we report a re-analysis of previously published data on warm dense hydrogen and helium, compare the newly inferred pressure, density, and temperature data with most advanced equation of state models and provide updated reflectivity values.

  14. Time- and space- resolved pyrometry of dense plasmas heated by laser accelerated ion beams

    NASA Astrophysics Data System (ADS)

    Dyer, Gilliss; Roycroft, Rebecca; McCary, Eddie; Wagner, Craig; Jiao, Xuejing; Kupfer, Rotem; Gauthier, D. Cort; Bang, Woosuk; Palaniyappan, Sasikumar; Bradley, Paul A.; Hamilton, Christopher; Santiago Cordoba, Miguel A.; Vold, Erik L.; Yin, Lin; Fernandez, Juan C.; Alibright, Brian J.; Ditmire, Todd; Hegelich, Bjorn Manuel

    2016-10-01

    Laser driven ion sources have a variety of possible applications, including the rapid heating of matter to dense plasma states of several eV. Recent experiments at LANL and The University of Texas have explored ion heating in the context of mixing at high-Z / low-Z plasma interfaces, using different laser-based ion acceleration schemes. Quasi-monoenergetic and highly directed Al ions from ultra-thin foils were used in one set of experiments, while TNSA accelerated protons from an F/40 focused petawatt laser were used in the other. Using spatially and temporally resolved streaked optical pyrometry we have gained insight into the degree and uniformity of heating from various configurations of ion source and sample target. Here we present data and analysis from three experimental runs along with hydrodynamic modeling of the heated targets and geometric considerations. This work was supported by NNSA cooperative agreement DE- NA0002008 and the Los Alamos National Laboratory Directed Research and Development Program under the auspices of the U.S. DOE NNSAS, LLC, Los Alamos National Laboratory under Contract No. DE-AC52-0.

  15. Magnetic phase diagram of dense holographic multiquarks in the quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Burikham, Piyabut

    2011-05-01

    We study phase diagram of the dense holographic gauge matter in the Sakai-Sugimoto model in the presence of the magnetic field above the deconfinement temperature. Even above the deconfinement, quarks could form colour bound states through the remaining strong interaction if the density is large. We demonstrate that in the presence of the magnetic field for a sufficiently large baryon density, the multiquark-pion gradient (MQ-∇ φ) phase is more thermodynamically preferred than the chiral-symmetric quark-gluon plasma. The phase diagrams between the holographic multiquark and the chiral-symmetric quark-gluon plasma phase are obtained at finite temperature and magnetic field. In the mixed MQ-∇ φ phase, the pion gradient induced by the external magnetic field is found to be a linear response for small and moderate field strengths. Its population ratio decreases as the density is raised and thus the multiquarks dominate the phase. Temperature dependence of the baryon chemical potential, the free energy and the linear pion gradient response of the multiquark phase are well approximated by a simple q analytic function sqrt {{1 - {{T^6}}/{T_0^6}}} inherited from the metric of the holographic background.

  16. Progress in Development of Dense Plasma Focus Pinch for AmBe Radiological Source Replacement

    NASA Astrophysics Data System (ADS)

    Falabella, Steve; Povilus, Alex; Schmidt, Andrea; Ellsworth, Jennifer; Link, Anthony; Sears, Jason; Higginson, Drew; Jiang, Sheng

    2015-11-01

    A dense plasma focus (DPF) is a compact plasma gun accelerator that can produce intense, high energy ion beams (multiple MeV). These ion beams could be used to replace radiological sources for a variety of applications. Using a 2kJ DPF with a helium gas fill, alpha particles are accelerated into a beryllium target in order to generate a neutron spectrum similar to an AmBe source. We report on initial observations of neutron yields for this system and efforts to optimize and improve repeatability of pinch performance. In particular, incorporating results from newly-developed kinetic LSP simulations, we demonstrated higher neutron yields by adjusting the geometry of the anode electrode. In addition, we present preliminary measurements for energy distributions of ions accelerated by the pinch. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work supported by US DOE/NA-22 Office of Non-proliferation Research and Development.

  17. Linear accelerator design study with direct plasma injection scheme for warm dense matter

    SciTech Connect

    Kondo, K.; Kanesue, T; Okamura, M.

    2011-03-28

    Warm Dense Matter (WDM) is a challenging science field, which is related to heavy ion inertial fusion and planetary science. It is difficult to expect the behavior because the state with high density and low temperature is completely different from ideal condition. The well-defined WDM generation is required to understand it. Moderate energy ion beams ({approx} MeV/u) slightly above Bragg peak is an advantageous method for WDM because of the uniform energy deposition. Direct Plasma Injection Scheme (DPIS) with a Interdigital H-mode (IH) accelerator has a potential for the beam parameter. We show feasible parameters of the IH accelerator for WDM. WDM physics is a challenging science and is strongly related to Heavy Ion Fusion science. WDM formation by Direct Plasma Injection Scheme (DPIS) with IH accelerator, which is a compact system, is proposed. Feasible parameters for IH accelerator are shown for WDM state. These represents that DPIS with IH accelerator can access a different parameter region of WDM.

  18. Ion probe beam experiments and kinetic modeling in a dense plasma focus Z-pinch

    SciTech Connect

    Schmidt, A. Ellsworth, J. Falabella, S. Link, A. McLean, H. Rusnak, B. Sears, J. Tang, V.; Welch, D.

    2014-12-15

    The Z-pinch phase of a dense plasma focus (DPF) emits multiple-MeV ions in a ∼cm length. The mechanisms through which these physically simple devices generate such high energy beams in a relatively short distance are not fully understood. We are exploring the origins of these large gradients using measurements of an ion probe beam injected into a DPF during the pinch phase and the first kinetic simulations of a DPF Z-pinch. To probe the accelerating fields in our table top experiment, we inject a 4 MeV deuteron beam along the z-axis and then sample the beam energy distribution after it passes through the pinch region. Using this technique, we have directly measured for the first time the acceleration of an injected ion beam. Our particle-in-cell simulations have been benchmarked on both a kJ-scale DPF and a MJ-scale DPF. They have reproduced experimentally measured neutron yields as well as ion beams and EM oscillations which fluid simulations do not exhibit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for accelerator and neutron source applications.

  19. Hydrogen production from dimethyl ether using corona discharge plasma

    NASA Astrophysics Data System (ADS)

    Zou, Ji-Jun; Zhang, Yue-Ping; Liu, Chang-Jun

    Dimethyl ether (DME), with its non-toxic character, high H/C ratio and high-energy volumetric density, is an ideal resource for hydrogen production. In this work, hydrogen production from the decomposition of DME using corona discharge has been studied. The corona discharge plasma decomposition was conducted at ambient conditions. The effects of dilution gas (argon), flow rate, frequency and waveforms on the DME decomposition were investigated. The addition of dilution gas can significantly increase the hydrogen production rate. The highest hydrogen production rate with the lowest energy consumption presents at the flow rate of 27.5 Nml min -1. AC voltage is more favored than DC voltage for the production of hydrogen with less energy input. The optimal frequency is 2.0 kHz. The hydrogen production rate is also affected by the input waveform and decreases as following: sinusoid triangular > sinusoid > ramp > square, whereas the sinusoid waveform shows the highest energy efficiency. The corona discharge decomposition of DME is leading to a simple, easy and convenient hydrogen production with no needs of catalyst and external heating.

  20. Optical emission spectroscopy of argon and hydrogen-containing plasmas

    NASA Astrophysics Data System (ADS)

    Siepa, Sarah; Danko, Stephan; Tsankov, Tsanko V.; Mussenbrock, Thomas; Czarnetzki, Uwe

    2015-09-01

    Optical emission spectroscopy (OES) on neutral argon is applied to investigate argon, hydrogen and hydrogen-silane plasmas. The spectra are analyzed using an extensive collisional-radiative model (CRM), from which the electron density and the electron temperature (or mean energy) can be calculated. The CRM also yields insight into the importance of different excited species and kinetic processes. The OES measurements are performed on pure argon plasmas at intermediate pressure. Besides, hydrogen and hydrogen-silane plasmas are investigated using argon as a trace gas. Especially for the gas mixture discharges, CRMs for low and high pressure differ substantially. The commonly used line-ratio technique is found to lose its sensitivity for gas mixture discharges at higher pressure. A solution using absolutely calibrated line intensities is proposed. The effect of radiation trapping and the shape of the electron energy distribution function on the results are discussed in detail, as they have been found to significantly influence the results. This work was supported by the Ruhr University Research School PLUS, funded by Germany's Excellence Initiative [DFG GSC 98/3].

  1. Restricted Path-Integral Molecular Dynamics for Simulating the Correlated Electron Plasma in Warm Dense Matter

    NASA Astrophysics Data System (ADS)

    Kapila, Vivek; Deymier, Pierre; Runge, Keith

    2011-10-01

    Several areas of study including heavy ion beam, large scale laser, and high pressure or Thomson scattering studies necessitate a fundamental understanding of warm dense matter (WDM) i.e. matter at high temperature and high density. The WDM regime, however, lacks any adequate highly developed class of simulation methods. Recent progress to address this deficit has been the development of orbital-free Density Functional Theory (ofDFT). However, scant benchmark information is available on temperature and pressure dependence of simple but realistic models in WDM regime. The present work aims to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Within the discrete path integral representation, electrons are described as harmonic necklaces. Quantum exchange takes the form of cross linking between electron necklaces. The fermion sign problem is addressed by restricting the density matrix to positive values. The molecular dynamics algorithm is employed to sample phase space. Here, we focus on the behavior of strongly correlated electron plasmas under WDM conditions. We compute the kinetic and potential energies and compare them to those obtained with the ofDFT method. Several areas of study including heavy ion beam, large scale laser, and high pressure or Thomson scattering studies necessitate a fundamental understanding of warm dense matter (WDM) i.e. matter at high temperature and high density. The WDM regime, however, lacks any adequate highly developed class of simulation methods. Recent progress to address this deficit has been the development of orbital-free Density Functional Theory (ofDFT). However, scant benchmark information is available on temperature and pressure dependence of simple but realistic models in WDM regime. The present work aims to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Within the discrete path integral representation, electrons are described as

  2. Influence of hydrogen and hydrogen/methane plasmas on AlN thin films

    SciTech Connect

    Pobedinskas, P. Hardy, A.; Van Bael, M. K.; Haenen, K.; Degutis, G.; Dexters, W.

    2014-02-24

    Polycrystalline aluminum nitride (AlN) thin films are exposed to hydrogen and hydrogen/methane plasmas at different conditions. The latter plays an indispensable role in the subsequent deposition of nanocrystalline diamond thin films on AlN. The changes of AlN properties are investigated by means of Fourier transform infrared (FTIR) and Raman spectroscopies as well as atomic force microscopy. The E{sub 1}(TO) and E{sub 2}{sup 2} phonon mode frequencies blue-shift after the exposure to plasmas. The damping constant of E{sub 1}(TO) phonon, calculated from FTIR transmission spectra using the factorized model of a damped oscillator, and the width of E{sub 2}{sup 2} peak in Raman spectra decrease with increasing substrate temperature till the decomposition of AlN thin film becomes notable. It is proven that these changes are driven by the plasmas as annealing in vacuum does not induce them.

  3. Effect of Hydrogen Plasma on Model Corrosion Layers of Bronze

    NASA Astrophysics Data System (ADS)

    Fojtíková, P.; Sázavská, V.; Mika, F.; Krčma, F.

    2016-05-01

    Our work is about plasmachemical reduction of model corrosion layers. The model corrosion layers were produced on bronze samples with size of 10 × 10 × 5 mm3, containing Cu and Sn. Concentrated hydrochloric acid was used as a corrosive environment. The application of reduction process in low-pressure low-temperature hydrogen plasma followed. A quartz cylindrical reactor with two outer copper electrodes was used. Plasma discharge was generated in pure hydrogen by a RF generator. Each corroded sample was treated in different conditions (supplied power and a continual or pulsed regime with a variable duty cycle mode). Process monitoring was ensured by optical emission spectroscopy. After treatment, samples were analyzed by SEM and EDX.

  4. Particle-in-cell modeling for MJ scale dense plasma focus with varied anode shape

    SciTech Connect

    Link, A. Halvorson, C. Schmidt, A.; Hagen, E. C.; Rose, D. V.; Welch, D. R.

    2014-12-15

    Megajoule scale dense plasma focus (DPF) Z-pinches with deuterium gas fill are compact devices capable of producing 10{sup 12} neutrons per shot but past predictive models of large-scale DPF have not included kinetic effects such as ion beam formation or anomalous resistivity. We report on progress of developing a predictive DPF model by extending our 2D axisymmetric collisional kinetic particle-in-cell (PIC) simulations from the 4 kJ, 200 kA LLNL DPF to 1 MJ, 2 MA Gemini DPF using the PIC code LSP. These new simulations incorporate electrodes, an external pulsed-power driver circuit, and model the plasma from insulator lift-off through the pinch phase. To accommodate the vast range of relevant spatial and temporal scales involved in the Gemini DPF within the available computational resources, the simulations were performed using a new hybrid fluid-to-kinetic model. This new approach allows single simulations to begin in an electron/ion fluid mode from insulator lift-off through the 5-6 μs run-down of the 50+ cm anode, then transition to a fully kinetic PIC description during the run-in phase, when the current sheath is 2-3 mm from the central axis of the anode. Simulations are advanced through the final pinch phase using an adaptive variable time-step to capture the fs and sub-mm scales of the kinetic instabilities involved in the ion beam formation and neutron production. Validation assessments are being performed using a variety of different anode shapes, comparing against experimental measurements of neutron yield, neutron anisotropy and ion beam production.

  5. Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

    NASA Astrophysics Data System (ADS)

    Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

    2013-10-01

    Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  6. Experimental Determination of DT Yield in High Current DD Dense Plasma Focii

    SciTech Connect

    Lowe, D. R.; Hagen, E. C.; Meehan, B. T.; Springs, R. K.; O'Brien, R. J.

    2013-06-18

    Dense Plasma Focii (DPF), which utilize deuterium gas to produce 2.45 MeV neutrons, may in fact also produce DT fusion neutrons at 14.1 MeV due to the triton production in the DD reaction. If beam-target fusion is the primary producer of fusion neutrons in DPFs, it is possible that ejected tritons from the first pinch will interact with the second pinch, and so forth. The 2 MJ DPF at National Security Technologies’ Losee Road Facility is able to, and has produced, over 1E12 DD neutrons per pulse, allowing an accurate measurement of the DT/DD ratio. The DT/DD ratio was experimentally verified by using the (n,2n) reaction in a large piece of praseodymium metal, which has a threshold reaction of 8 MeV, and is widely used as a DT yield measurement system1. The DT/DD ratio was experimentally determined for over 100 shots, and then compared to independent variables such as tube pressure, number of pinches per shot, total current, pinch current and charge voltage.

  7. Radiation Characteristics of the FN-II Dense Plasma Focus Device

    NASA Astrophysics Data System (ADS)

    Castillo-Mejía, Fermín; Herrera-Velázquez, J. Julio E.; Gamboa-deBuen, I.; Rangel-Gutiérrez, José; Villalobos-Pérez, Salvador

    2008-04-01

    The Fuego Nuevo II (FN-II) dense plasma focus device is a small machine (4.6 kJ), operating at the Instituto de Ciencias Nucleares, UNAM, in which neutrons, as well as soft and hard X rays have been studied with a number of diagnostics. Neutrons are studied with silver activation counters, and scintillator-photomultiplier detectors, while their angular distribution inside and outside the discharge chamber have been studied with CR-39 plastic track detectors. The soft X rays are studied with a multiple-pin-hole camera and PIN diodes, while the hard X-rays are observed with the scintillator-photomultiplier detectors mentioned above. When a needle is inserted on the inner electrode, a bright spot of hard x-rays can be concentrated, and used for the production of high-contrast radiography. Dosimetric measurements have been made for X-rays crossing a 300 micron aluminum window, through the axis of the machine, showing an average dose of 0.11±0.01 mGy per shot. In contrast, the average dose with a hollow cathode is 0.077±0.006 mGy per shot.

  8. Ionic structures and transport properties of hot dense W and U plasmas

    NASA Astrophysics Data System (ADS)

    Hou, Yong; Yuan, Jianmin

    2016-10-01

    We have combined the average-atom model with the hyper-netted chain approximation (AAHNC) to describe the electronic and ionic structure of uranium and tungsten in the hot dense matter regime. When the electronic structure is described within the average-atom model, the effects of others ions on the electronic structure are considered by the correlation functions. And the ionic structure is calculated though using the hyper-netted chain (HNC) approximation. The ion-ion pair potential is calculated using the modified Gordon-Kim model based on the electronic density distribution in the temperature-depended density functional theory. And electronic and ionic structures are determined self-consistently. On the basis of the ion-ion pair potential, we perform the classical (CMD) and Langevin (LMD) molecular dynamics to simulate the ionic transport properties, such as ionic self-diffusion and shear viscosity coefficients, through the ionic velocity correlation functions. Due that the free electrons become more and more with increasing the plasma temperature, the influence of the electron-ion collisions on the transport properties become more and more important.

  9. Tracing Dense and Diffuse Neutral Hydrogen in the Halo of the Milky Way

    NASA Astrophysics Data System (ADS)

    Moss, V. A.; Lockman, F. J.; McClure-Griffiths, N. M.

    2017-01-01

    We have combined observations of Galactic high-velocity H i from two surveys: a very sensitive survey from the Green Bank 140 ft Telescope with limited sky coverage, and the less sensitive but complete Galactic All Sky Survey from the 64 m Parkes Radio Telescope. The two surveys preferentially detect different forms of neutral gas due to their sensitivity. We adopt a machine learning approach to divide our data into two populations that separate across a range in column density: (1) a narrow line-width population typical of the majority of bright high velocity cloud components, and (2) a fainter, broad line-width population that aligns well with that of the population found in the Green Bank survey. We refer to these populations as dense and diffuse gas, respectively, and find that diffuse gas is typically located at the edges and in the tails of high velocity clouds, surrounding dense components in the core. A fit to the average spectrum of each type of gas in the Galactic All Sky Survey data reveals the dense population to have a typical line width of ∼20 km s‑1 and brightness temperature of ∼0.3 K, while the diffuse population has a typical line width of ∼30 km s‑1 and a brightness temperature of ∼0.2 K. Our results confirm that most surveys of high velocity gas in the Milky Way halo are missing the majority of the ubiquitous diffuse gas, and that this gas is likely to contribute at least as much mass as the dense gas.

  10. Development of mixed-conducting dense ceramic membranes for hydrogen separation.

    SciTech Connect

    Balachandran, U.; Bose, A. C.; Guan, J.; Stiegel, G. J.

    1998-04-17

    The electronic transference numbers of BCY were relatively low when compared with the protonic numbers. At 800 C, a hydrogen flux of only 0.02 cm{sup 3}/min/cm{sup 2} was obtained in an {approx} 2-rnm-thick BCY sample by short-circuiting the two Pt electrodes. We have developed a novel composite system with improved electronic transport, and preliminary measurements indicate that the new membrane materials can be used in a nongalvanic mode to separate hydrogen from gas mixtures. A maximum flux of 0.12 cm{sup 3}/min/cm{sup 2} has been measured at 800 C in the composite material operated in the nongalvanic mode. Currently, work is underway to further enhance the hydrogen flux in the composite membrane materials.

  11. Electrostatic modes in dense dusty plasmas with high fugacity: Numerical results

    NASA Astrophysics Data System (ADS)

    Rao, N. N.

    2000-08-01

    The existence of ultra low-frequency wave modes in dusty plasmas has been investigated over a wide range of dust fugacity [defined by f≡4πnd0λD2R, where nd0 is the dust number density, λD is the plasma Debye length, and R is the grain size (radius)] and the grain charging frequency (ω1) by numerically solving the dispersion relation obtained from the kinetic (Vlasov) theory. A detailed comparison between the numerical and the analytical results applicable for the tenuous (low fugacity, f≪1), the dilute (medium fugacity, f˜1), and the dense (high fugacity, f≫1) regimes has been carried out. In the long wavelength limit and for frequencies ω≪ω1, the dispersion curves obtained from the numerical solutions of the real as well as the complex (kinetic) dispersion relations agree, both qualitatively and quantitatively, with the analytical expressions derived from the fluid and the kinetic theories, and are thus identified with the ultra low-frequency electrostatic dust modes, namely, the dust-acoustic wave (DAW), the dust charge-density wave (DCDW) and the dust-Coulomb wave (DCW) discussed earlier [N. N. Rao, Phys. Plasmas 6, 4414 (1999); 7, 795 (2000)]. In particular, the analytical scaling between the phase speeds of the DCWs and the DAWs predicted from theoretical considerations, namely, (ω/k)DCW=(ω/k)DAW/√fδ (where δ is the ratio of the charging frequencies) is in excellent agreement with the numerical results. A simple physical picture of the DCWs has been proposed by defining an effective pressure called "Coulomb pressure" as PC≡nd0qd02/R, where qd0 is the grain surface charge. Accordingly, the DCW dispersion relation is given, in the lowest order, by (ω/k)DCW=√PC/ρdδ , where ρd≡nd0md is the dust mass density. Thus, the DCWs which are driven by the Coulomb pressure can be considered as the electrostatic analogue of the hydromagnetic (Alfvén or magnetoacoustic) waves which are driven by the magnetic field pressure. For the frequency

  12. Ortho- and para-hydrogen in dense clouds, protoplanets, and planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Decampli, W. M.; Cameron, A. G. W.; Bodenheimer, P.; Black, D. C.

    1978-01-01

    If ortho- and para-hydrogen achieve a thermal ratio on dynamical time scales in a molecular hydrogen cloud, then the specific heat is high enough in the temperature range 35-70 K to possibly induce hydrodynamic collapse. The ortho-para ratio in many interstellar cloud fragments is expected to meet this condition. The same may have been true for the primitive solar nebula. Detailed hydrodynamic and hydrostatic calculations are presented that show the effects of the assumed ortho-para ratio on the evolution of Jupiter during its protoplanetary phase. Some possible consequences of a thermalized ortho-para ratio in the atmospheres of the giant planets are also discussed.

  13. Thermodynamics of dense molecular hydrogen-helium mixtures at high pressure

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.; Hubbard, William B.

    1988-01-01

    Effective intermolecular pair potentials derived from liquid hydrogen and helium shock wave experiments are presently used in Monte Carlo simulations of mixtures of hydrogen and helium, at densities of up to 1.2 g/cu cm. The model interaction Helmholtz free energy derived accurately reproduces both the Monte Carlo calculation results and the experimental data obtained for densities of up to about 0.6 g/cu cm. An equation of state is derived from the free energy expression that could be useful in interior models of such Jovian planets as Saturn.

  14. Direct synthesis of hydrogen peroxide from plasma-water interactions

    NASA Astrophysics Data System (ADS)

    Liu, Jiandi; He, Bangbang; Chen, Qiang; Li, Junshuai; Xiong, Qing; Yue, Guanghui; Zhang, Xianhui; Yang, Size; Liu, Hai; Liu, Qing Huo

    2016-12-01

    Hydrogen peroxide (H2O2) is usually considered to be an important reagent in green chemistry since water is the only by-product in H2O2 involved oxidation reactions. Early studies show that direct synthesis of H2O2 by plasma-water interactions is possible, while the factors affecting the H2O2 production in this method remain unclear. Herein, we present a study on the H2O2 synthesis by atmospheric pressure plasma-water interactions. The results indicate that the most important factors for the H2O2 production are the processes taking place at the plasma-water interface, including sputtering, electric field induced hydrated ion emission, and evaporation. The H2O2 production rate reaches ~1200 μmol/h when the liquid cathode is purified water or an aqueous solution of NaCl with an initial conductivity of 10500 μS cm‑1.

  15. Direct synthesis of hydrogen peroxide from plasma-water interactions.

    PubMed

    Liu, Jiandi; He, Bangbang; Chen, Qiang; Li, Junshuai; Xiong, Qing; Yue, Guanghui; Zhang, Xianhui; Yang, Size; Liu, Hai; Liu, Qing Huo

    2016-12-05

    Hydrogen peroxide (H2O2) is usually considered to be an important reagent in green chemistry since water is the only by-product in H2O2 involved oxidation reactions. Early studies show that direct synthesis of H2O2 by plasma-water interactions is possible, while the factors affecting the H2O2 production in this method remain unclear. Herein, we present a study on the H2O2 synthesis by atmospheric pressure plasma-water interactions. The results indicate that the most important factors for the H2O2 production are the processes taking place at the plasma-water interface, including sputtering, electric field induced hydrated ion emission, and evaporation. The H2O2 production rate reaches ~1200 μmol/h when the liquid cathode is purified water or an aqueous solution of NaCl with an initial conductivity of 10500 μS cm(-1).

  16. Plasma Depolymerization of Chitosan in the Presence of Hydrogen Peroxide

    PubMed Central

    Ma, Fengming; Wang, Zhenyu; Zhao, Haitian; Tian, Shuangqi

    2012-01-01

    The depolymerization of chitosan by plasma in the presence of hydrogen peroxide (H2O2) was investigated. The efficiency of the depolymerization was demonstrated by means of determination of viscosity-average molecular weight and gel permeation chromatography (GPC). The structure of the depolymerized chitosan was characterized by Fourier-transform infrared spectra (FT-IR), ultraviolet spectra (UV) and X-ray diffraction (XRD). The results showed that chitosan can be effectively degradated by plasma in the presence of H2O2. The chemical structure of the depolymerized chitosan was not obviously modified. The combined plasma/H2O2 method is significantly efficient for scale-up manufacturing of low molecular weight chitosan. PMID:22837727

  17. Ion energy distributions in silane-hydrogen plasmas

    SciTech Connect

    Hamers, E.A.G.; Sark, W.G.J.H.M. van; Bezemer, J.; Weg, W.F. van der; Goedheer, W.J.

    1996-12-31

    For the first time ion energy distributions (IED) of different ions from silane-hydrogen (SiH{sub 4}-H{sub 2}) RF plasmas are presented, i.e., the distributions of SiH{sub 3}{sup +}, SiH{sub 2}{sup +} and Si{sub 2}H{sub 4}{sup +}. The energy distributions of SiH{sub 3}{sup +} and SiH{sub 2}{sup +} ions show peaks, which are caused by a charge exchange process in the sheath. A method is presented by which the net charge density in the sheath is determined from the plasma potential and the energy positions of the charge exchange peaks. Knowing the net charge density in the sheath and the plasma potential, the sheath thickness can be determined and an estimation of the absolute ion fluxes can be made. The flux of ions can, at maximum, account for 10% of the observed deposition rate.

  18. Enhanced magnetic ionization in hydrogen reflex discharge plasma source

    SciTech Connect

    Toader, E.I.; Covlea, V.N.

    2005-03-01

    The effect of enhanced magnetic ionization on the external and internal parameters of a high-density, low pressure reflex plasma source operating in hydrogen is studied. The Langmuir probe method and Druyvesteyn procedure coupled with suitable software are used to measure the internal parameters. The bulk plasma region is free of an electric field and presents a high degree of uniformity. The electron energy distribution function is bi-Maxwellian with a dip/shoulder structure around 5.5 eV, independent of external parameters and radial position. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the electron density n{sub e} is as high as 10{sup 18} m{sup -3}, and the electron temperature T{sub e} is as low as a few tens of an electron volt, for dissipated energy of tens of Watts. The bulk plasma density scales with the dissipated power.

  19. Energy Dense, Lighweight, Durable, Systems for Storage and Delivery of Hydrogen

    SciTech Connect

    Jacky Pruez; Samir Shoukry; Gergis William; Thomas Evans; Hermann Alcazar

    2008-12-31

    The work presented in this report summarizes the current state-of-the-art in on-board storage on compressed gaseous hydrogen as well as the development of analysis tools, methods, and theoretical data for devising high performance design configurations for hydrogen storage. The state-of-the-art in the area of compressed hydrogen storage reveals that the current configuration of the hydrogen storage tank is a seamless cylindrical part with two end domes. The tank is composed of an aluminum liner overwrapped with carbon fibers. Such a configuration was proved to sustain internal pressures up to 350 bars (5,000 psi). Finite-element stress analyses were performed on filament-wound hydrogen storage cylindrical tanks under the effect of internal pressure of 700 bars (10,000 psi). Tank deformations, stress fields, and intensities induced at the tank wall were examined. The results indicated that the aluminum liner can not sustain such a high pressure and initiate the tank failure. Thus, hydrogen tanks ought to be built entirely out of composite materials based on carbon fibers or other innovative composite materials. A spherical hydrogen storage tank was suggested within the scope of this project. A stress reduction was achieved by this change of the tank geometry, which allows for increasing the amount of the stored hydrogen and storage energy density. The finite element modeling of both cylindrical and spherical tank design configurations indicate that the formation of stress concentration zones in the vicinity of the valve inlet as well as the presence of high shear stresses in this area. Therefore, it is highly recommended to tailor the tank wall design to be thicker in this region and tapered to the required thickness in the rest of the tank shell. Innovative layout configurations of multiple tanks for enhanced conformability in limited space have been proposed and theoretically modeled using 3D finite element analysis. Optimum tailoring of fiber orientations and lay

  20. Novel Composite Hydrogen-Permeable Membranes for Nonthermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    SciTech Connect

    Morris Argyle; John Ackerman; Suresh Muknahallipatna; Jerry Hamann; Stanislaw Legowski; Gui-Bing Zhao; Sanil John; Ji-Jun Zhang; Linna Wang

    2007-09-30

    The goal of this experimental project was to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a nonthermal plasma and to recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), but it was not achieved at the moderate pressure conditions used in this study. However, H{sub 2}S was successfully decomposed at energy efficiencies higher than any other reports for the high H{sub 2}S concentration and moderate pressures (corresponding to high reactor throughputs) used in this study.

  1. Effect of the liquid-like ionic structure on the electron-ion energy relaxation timescales in dense plasmas

    NASA Astrophysics Data System (ADS)

    Daligault, Jérôme; Mozyrsky, Dmitry

    2008-04-01

    In a recent publication [J. Daligault, D. Mozyrsky, Phys. Rev. E 75 (2007) 026402], we derived a general expression for the electron-ion energy relaxation rate in plasmas which, as a result of the small electron-ion mass ratio, expresses the relaxation rate in terms of the low-frequency electronic density fluctuations. Here we propose a practical model for the electronic density fluctuations in dense plasmas and apply this model to the calculation of the electron-ion energy relaxation rate. We find that the rate is only scarcely affected by the underlying liquid-like ionic disorder typical of dense matter. Relaxation rates obtained are systematically slightly larger than those predicted by the Fermi Golden Rule formula, in contradiction with the coupled-modes' theory that predicts values an order of magnitude lower. We also find that the discontinuity of the rate at melting is tiny, in contrast with the sharp increase of the electrical conductivity.

  2. Studies on plasma profiles and its effect on dust charging in hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Kakati, B.; Kausik, S. S.; Saikia, B. K.; Bandyopadhay, M.

    2010-02-01

    Plasma profiles and its influence on dust charging are studied in hydrogen plasma. The plasma is produced in a high vacuum device by a hot cathode discharge method and is confined by a cusped magnetic field cage. A cylindrical Espion advanced Langmuir probe having 0.15 mm diameter and 10.0 mm length is used to study the plasma parameters for various discharge conditions. Optimum operational discharge parameters in terms of charging of the dust grains are studied. The charge on the surface of the dust particle is calculated from the capacitance model and the current by the dust grains is measured by the combination of a Faraday cup and an electrometer. Unlike our previous experiments in which dust grains were produced in-situ, here a dust dropper is used to drop the dust particles into the plasma.

  3. Magnetization processes in two different types of anisotropic, fully dense NdFeB hydrogenation, disproportionation, desorption, and recombination magnets

    NASA Astrophysics Data System (ADS)

    Gutfleisch, O.; Eckert, D.; Schäfer, R.; Müller, K. H.; Panchanathan, V.

    2000-05-01

    Two types of textured, fully dense NdFeB hydrogenation, disproportionation, desorption, and recombination (HDDR) magnets were produced. The first type was produced by hot pressing isotropic HDDR powder followed by die upsetting; the second, by hot pressing prealigned, anisotropic HDDR powder (MQA-T). Studies of the magnetization processes revealed that for isotropic HDDR powder and its hot pressed and die-upset magnets a much larger initial susceptibility is found after thermal demagnetization than after reverse dc-field demagnetization. Prealigned, hot pressed magnets made from MQA-T material showed a different virgin magnetization curve, indicating a unique coercivity mechanism. Interaction domains larger than the average grain size can be observed in both cases by Kerr microscopy, with the MQA-T type showing significantly broader interaction domains.

  4. Low-temperature phases of dense hydrogen and deuterium by first-principles path-integral molecular dynamics

    NASA Astrophysics Data System (ADS)

    Torrent, Marc; Geneste, Gregory

    2012-02-01

    The low-temperature phases of dense hydrogen and deuterium have been investigated using first-principles path-integral molecular dynamics, a technique that we have recently implemented in the ABINIT code and that allows to account for the quantum fluctuations of atomic nuclei. A massively parallelized scheme is applied to produce trajectories of several tens of thousands steps using a 64-atom supercell and a Trotter number of 64. The so-called phases I, II and III are studied and compared to the structures proposed in the literature. The quantum fluctuations produce configurational disorder and are shown to systematically enhance the symmetry of the system: a continuous gain of symmetry in the angular density of probability of the molecules is found from classical particles to quantum D2 and finally to quantum H2. Particular emphasis is made on the ``broken-symmetry'' phase (phase II).

  5. Negative hydrogen ion production in a helicon plasma source

    SciTech Connect

    Santoso, J. Corr, C. S.; Manoharan, R.; O'Byrne, S.

    2015-09-15

    In order to develop very high energy (>1 MeV) neutral beam injection systems for applications, such as plasma heating in fusion devices, it is necessary first to develop high throughput negative ion sources. For the ITER reference source, this will be realised using caesiated inductively coupled plasma devices, containing either hydrogen or deuterium discharges, operated with high rf input powers (up to 90 kW per driver). It has been suggested that due to their high power coupling efficiency, helicon devices may be able to reduce power requirements and potentially obviate the need for caesiation due to the high plasma densities achievable. Here, we present measurements of negative ion densities in a hydrogen discharge produced by a helicon device, with externally applied DC magnetic fields ranging from 0 to 8.5 mT at 5 and 10 mTorr fill pressures. These measurements were taken in the magnetised plasma interaction experiment at the Australian National University and were performed using the probe-based laser photodetachment technique, modified for the use in the afterglow of the plasma discharge. A peak in the electron density is observed at ∼3 mT and is correlated with changes in the rf power transfer efficiency. With increasing magnetic field, an increase in the negative ion fraction from 0.04 to 0.10 and negative ion densities from 8 × 10{sup 14 }m{sup −3} to 7 × 10{sup 15 }m{sup −3} is observed. It is also shown that the negative ion densities can be increased by a factor of 8 with the application of an external DC magnetic field.

  6. Negative hydrogen ion production in a helicon plasma source

    NASA Astrophysics Data System (ADS)

    Santoso, J.; Manoharan, R.; O'Byrne, S.; Corr, C. S.

    2015-09-01

    In order to develop very high energy (>1 MeV) neutral beam injection systems for applications, such as plasma heating in fusion devices, it is necessary first to develop high throughput negative ion sources. For the ITER reference source, this will be realised using caesiated inductively coupled plasma devices, containing either hydrogen or deuterium discharges, operated with high rf input powers (up to 90 kW per driver). It has been suggested that due to their high power coupling efficiency, helicon devices may be able to reduce power requirements and potentially obviate the need for caesiation due to the high plasma densities achievable. Here, we present measurements of negative ion densities in a hydrogen discharge produced by a helicon device, with externally applied DC magnetic fields ranging from 0 to 8.5 mT at 5 and 10 mTorr fill pressures. These measurements were taken in the magnetised plasma interaction experiment at the Australian National University and were performed using the probe-based laser photodetachment technique, modified for the use in the afterglow of the plasma discharge. A peak in the electron density is observed at ˜3 mT and is correlated with changes in the rf power transfer efficiency. With increasing magnetic field, an increase in the negative ion fraction from 0.04 to 0.10 and negative ion densities from 8 × 1014 m-3 to 7 × 1015 m-3 is observed. It is also shown that the negative ion densities can be increased by a factor of 8 with the application of an external DC magnetic field.

  7. Thermodynamics and phase separation of dense fully-ionized hydrogen-helium fluid mixtures

    NASA Technical Reports Server (NTRS)

    Stevenson, D. J.

    1975-01-01

    The free energy of a hydrogen-helium fluid mixture is evaluated for the temperatures and densities appropriate to the deep interior of a giant planet such as Jupiter. The electrons are assumed to be fully pressure-ionized and degenerate. In this regime, an appropriate first approximation to the ionic distribution functions can be found by assuming hard sphere interactions. Corrections to this approximation are incorporated by means of the perturbation theory of Anderson and Chandler. Approximations for the three-body interactions and the nonlinear response of the electron gas to the ions are included. It is predicted that a hydrogen-helium mixture, containing 10% by number of helium ions, separates into hydrogen-rich and helium-rich phases below about 8000 K, at the pressures relevant to Jupiter (4-40 Megabars). It is also predicted that the alloy occupies less volume per ion than the separated phases. The equations of state and other thermodynamic derivatives are tabulated. Implications of these results are discussed.

  8. SOLUBILITY OF IRON IN METALLIC HYDROGEN AND STABILITY OF DENSE CORES IN GIANT PLANETS

    SciTech Connect

    Wahl, Sean M.; Wilson, Hugh F.; Militzer, Burkhard

    2013-08-20

    The formation of the giant planets in our solar system, and likely a majority of giant exoplanets, is most commonly explained by the accretion of nebular hydrogen and helium onto a large core of terrestrial-like composition. The fate of this core has important consequences for the evolution of the interior structure of the planet. It has recently been shown that H{sub 2}O, MgO, and SiO{sub 2} dissolve in liquid metallic hydrogen at high temperature and pressure. In this study, we perform ab initio calculations to study the solubility of an innermost metallic core. We find dissolution of iron to be strongly favored above 2000 K over the entire pressure range (0.4-4 TPa) considered. We compare with and summarize the results for solubilities on other probable core constituents. The calculations imply that giant planet cores are in thermodynamic disequilibrium with surrounding layers, promoting erosion and redistribution of heavy elements. Differences in solubility behavior between iron and rock may influence evolution of interiors, particularly for Saturn-mass planets. Understanding the distribution of iron and other heavy elements in gas giants may be relevant in understanding mass-radius relationships, as well as deviations in transport properties from pure hydrogen-helium mixtures.

  9. Liquid-vapor equilibrium-states and critical properties of aluminum from dense plasma equation-of-state

    NASA Astrophysics Data System (ADS)

    Zaghloul, Mofreh

    2016-10-01

    We present successful estimates of the critical properties and liquid-vapor equilibrium states of pure aluminum fluid as predicted from a chemical model for the equation-of-state of hot dense partially ionized plasma. The essential features of strongly-coupled plasma of metal vapors, such as, multiple ionization, Coulomb interactions among charged particles, partial degeneracy, and intensive short range hard core repulsion are taken into consideration. Internal partition functions of neutral, excited, and ionized species are thoughtfully evaluated in a statistical-mechanically consistent way implementing recent developments in the literature. Results predicted from the present model are discussed and carefully examined against available data and predictions in the literature.

  10. Free-Free Transitions of e-H System Inside a Dense Plasma Irradiated by a Laser Field at Very Low Incident Electron Energies

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Sinha, C.

    2012-01-01

    The free-free transition is studied for an electron-hydrogen in the ground state at low incident energies in the presence of an external homogenous, monochromatic, and linearly polarized laser-field inside a hot dense plasma.The effect of plasma screening is considered in the Debye-Huckel approximation. The calculations are performed in the soft photon limit, assuming that the plasma frequency is much higher than the laser frequency. The incident electron is considered to be dressed by the laser field in a nonperturbative manner by choosing the Volkov solutions in both the initial and final channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the electron exchange. The laser-assisted differential and total cross sections are calculated for single-photon absorption /emission and no photon exchange in the soft photon limit, the laser intensity being much less than the atomic field intensity. The calculations have been carried out for various values of Debye parameter, ranging from 0.005 to 0.12. A strong suppression is noted in the laser-assisted cross sections as compared to the field-free situation. A significant difference is noted for the singlet and triplet cross sections. The suppression is much more in the triplet states.

  11. The K x-ray line structures of the 3d-transition metals in warm dense plasma

    NASA Astrophysics Data System (ADS)

    Szymańska, E.; Syrocki, Ł.; Słabkowska, K.; Polasik, M.; Rzadkiewicz, J.

    2016-09-01

    The shapes and positions of the Kα1 and Kα2 x-ray lines for 3d-transition metals can vary substantially as electrons are stripped from the outer-shells. This paper shows the detailed line shapes for nickel and zinc, obtained by calculations with a multiconfiguration Dirac-Fock method that includes Breit interaction and quantum electrodynamics corrections. The line shapes can be useful in interpreting hot, dense plasmas with energetic electrons for which the K x-ray lines are optically thin, as may be produced by pulsed power machines such as the plasma-filled rod pinch diode or the plasma focus, or in short-pulsed high power laser plasmas.

  12. Simulations of the interaction of intense petawatt laser pulses with dense Z-pinch plasmas : final report LDRD 39670.

    SciTech Connect

    Welch, Dale Robert; MacFarlane, Joseph John; Mehlhorn, Thomas Alan; Campbell, Robert B.

    2004-11-01

    We have studied the feasibility of using the 3D fully electromagnetic implicit hybrid particle code LSP (Large Scale Plasma) to study laser plasma interactions with dense, compressed plasmas like those created with Z, and which might be created with the planned ZR. We have determined that with the proper additional physics and numerical algorithms developed during the LDRD period, LSP was transformed into a unique platform for studying such interactions. Its uniqueness stems from its ability to consider realistic compressed densities and low initial target temperatures (if required), an ability that conventional PIC codes do not possess. Through several test cases, validations, and applications to next generation machines described in this report, we have established the suitability of the code to look at fast ignition issues for ZR, as well as other high-density laser plasma interaction problems relevant to the HEDP program at Sandia (e.g. backlighting).

  13. The interaction between two planar and nonplanar quantum electron acoustic solitary waves in dense electron-ion plasmas

    SciTech Connect

    EL-Labany, S. K.; El-Mahgoub, M. G.; EL-Shamy, E. F.

    2012-06-15

    The interaction between two planar and nonplanar (cylindrical and spherical) quantum electron acoustic solitary waves (QEASWs) in quantum dense electron-ion plasmas has been studied. The extended Poincare-Lighthill-Kuo method is used to obtain planar and nonplanar phase shifts after the interaction of the two QEASWs. The change of phase shifts and trajectories for QEASWs due to the effect of the different geometries, the quantum corrections of diffraction, and the cold electron-to-hot electron number density ratio are discussed. It is shown that the interaction of the QEASWs in planar geometry, cylindrical geometry, and spherical geometry are different. The present investigation may be beneficial to understand the interaction between two planar and nonplanar QEASWs that may occur in the quantum plasmas found in laser-produced plasmas as well as in astrophysical plasmas.

  14. Numerical Study on the Acetylene Concentration in the Hydrogen-Carbon System in a Hydrogen Plasma Torch

    NASA Astrophysics Data System (ADS)

    Chen, Longwei; Shen, Jie; Shu, Xingsheng; Fang, Shidong; Zhang, Lipeng; Meng, Yuedong

    2009-06-01

    Effects of the hydrogen/carbon mole ratio and pyrolysis gas pressure on the acetylene concentration in the hydrogen-carbon system in a plasma torch were numerically calculated by using the chemical thermodynamic equilibrium method of Gibbs free energy. The calculated results indicate that the hydrogen concentration and the pyrolysis gas pressure play crucial roles in acetylene formation. Appropriately abundant hydrogen, with a mole ratio of hydrogen to carbon about 1 or 2, and a relatively high pyrolysis gas pressure can enhance the acetylene concentration. In the experiment, a compromised project consisting of an appropriate hydrogen flow rate and a feasible high pyrolysis gas pressure needs to be carried out to increase the acetylene concentration from coal pyrolysis in the hydrogen plasma torch.

  15. Characterization of the conduction phase of a plasma opening switch using a hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Moschella, J. J.; Klepper, C. C.; Vidoli, C.; Yadlowsky, E. J.; Weber, B. V.; Commisso, R. J.; Black, D. C.; Moosman, B.; Stephanakis, S. J.; Hinshelwood, D. D.; Maron, Y.

    2005-02-01

    Plasma opening switch (POS) experiments were conducted on the Hawk generator using an inverse pinch plasma source to inject a hydrogen plasma. Using a combination of interferometry, current measurements, and spectroscopic observations, it is shown that the conduction phase is characterized by the propagation of a current channel through the switch region that pushes a significant fraction of the plasma mass downstream, past the load edge of the switch. The data indicate that the current channel arrives at the load edge of the switch ≈550ns into the 950-ns-long conduction phase, in agreement with calculations based on J ×B displacement. Previously published POS experiments, using multispecies plasmas, observed that a relatively small fraction of the injected plasma mass propagated downstream and that the conduction phase ended soon after the current channel reached the load edge of the switch. It is suggested that the observed differences between these two types of switches involves the separation of ionic species subject to a magnetic force, where the light-ion plasma is pushed ahead of the magnetic field front and the heavier-ion plasma is penetrated by the field. Species-separation effects may be important in a multispecies POS but would be negligible in this almost pure (>95%) proton-plasma experiment. While the important role of the plasma composition in pulsed magnetic field plasma interactions has been pointed out in previous experimental studies, this work demonstrates that the plasma composition can have a significant effect on the conduction time of a POS.

  16. Negative hydrogen ions in a linear helicon plasma device

    NASA Astrophysics Data System (ADS)

    Corr, Cormac; Santoso, Jesse; Samuell, Cameron; Willett, Hannah; Manoharan, Rounak; O'Byrne, Sean

    2015-09-01

    Low-pressure negative ion sources are of crucial importance to the development of high-energy (>1 MeV) neutral beam injection systems for the ITER experimental tokamak device. Due to their high power coupling efficiency and high plasma densities, helicon devices may be able to reduce power requirements and potentially remove the need for caesium. In helicon sources, the RF power can be coupled efficiently into the plasma and it has been previously observed that the application of a small magnetic field can lead to a significant increase in the plasma density. In this work, we investigate negative ion dynamics in a high-power (20 kW) helicon plasma source. The negative ion fraction is measured by probe-based laser photodetachment, electron density and temperature are determined by a Langmuir probe and tuneable diode laser absorption spectroscopy is used to determine the density of the H(n = 2) excited atomic state and the gas temperature. The negative ion density and excited atomic hydrogen density display a maximum at a low applied magnetic field of 3 mT, while the electron temperature displays a minimum. The negative ion density can be increased by a factor of 8 with the application of the magnetic field. Spatial and temporal measurements will also be presented. The Australian Research Grants Council is acknowledged for funding.

  17. Effect of dense plasmas on exchange-energy shifts in highly charged ions: An alternative approach for arbitrary perturbation potentials

    SciTech Connect

    Rosmej, F.; Bennadji, K.; Lisitsa, V. S.

    2011-09-15

    An alternative method of calculation of dense plasma effects on exchange-energy shifts {Delta}E{sub x} of highly charged ions is proposed which results in closed expressions for any plasma or perturbation potential. The method is based on a perturbation theory expansion for the inner atomic potential produced by charged plasma particles employing the Coulomb Green function method. This approach allows us to obtain analytic expressions and scaling laws with respect to the electron temperature T, density n{sub e}, and nuclear charge Z. To demonstrate the power of the present method, two specific models were considered in detail: the ion sphere model (ISM) and the Debye screening model (DSM). We demonstrate that analytical expressions can be obtained even for the finite temperature ISM. Calculations have been carried out for the singlet 1s2p{sup 1} P{sub 1} and triplet 1s2p{sup 3} P{sub 1} configurations of He-like ions with charge Z that can be observed in dense plasmas via the He-like resonance and intercombination lines. Finally we discuss recently available purely numerical calculations and experimental data.

  18. Measurements of plasma spectra from hot dense elements and mixtures at conditions relevant to the solar radiative zone

    NASA Astrophysics Data System (ADS)

    Hoarty, D. J.; Hill, E.; Beiersdorfer, P.; Allan, P.; Brown, C. R. D.; Hill, M. P.; Hobbs, L. M. R.; James, S. F.; Morton, J.; Sircombe, N.; Upcraft, L.; Harris, J. W. O.; Shepherd, R.; Marley, E.; Magee, E.; Emig, J.; Nilsen, J.; Rose, S. J.

    2017-03-01

    X-ray emission spectroscopy has been used to study hot dense plasmas produced using high power laser irradiation of dot samples buried in low Z foils of plastic or diamond. By combining a high contrast short pulse (picosecond timescale) laser beam operating in second harmonic with long pulse (nanosecond timescale) laser beams in third harmonic, and with pulse shaping of the long pulse beams, a range of plasma temperatures from 400eV up to 2.5keV and electron densities from 5e22 up to 1e24/cc have been accessed. Examples are given of measurements of dense plasma effects such as ionization potential depression and line-broadening from the K-shell emission spectra of a range of low Z elements and mixtures and compared to model prediction. Detailed spectra from measurements of the L-shell emission from mid-Z elements are also presented for an example spectrum of germanium. These data are at conditions found in stellar interiors and in particular in the radiative zone of the sun. The plasma conditions are inferred from comparison of the measured spectra to detailed modeling using atomic kinetics and spectral synthesis codes.

  19. Accelerating ab initio Molecular Dynamics and Probing the Weak Dispersive Forces in Dense Liquid Hydrogen

    NASA Astrophysics Data System (ADS)

    Mazzola, Guglielmo; Sorella, Sandro

    2017-01-01

    We propose an ab initio molecular dynamics method, capable of dramatically reducing the autocorrelation time required for the simulation of classical and quantum particles at finite temperatures. The method is based on an efficient implementation of a first order Langevin dynamics modified by means of a suitable, position dependent acceleration matrix S . Here, we apply this technique to both Lennard-Jones models, to demonstrate the accuracy and speeding-up of the sampling, and within a quantum Monte Carlo based wave function approach, for determining the phase diagram of high-pressure hydrogen with simulations much longer than the autocorrelation time. With the proposed method, we are able to equilibrate in a few hundred steps even close to the liquid-liquid phase transition (LLT). Within our approach, we find that the LLT transition is consistent with recent density functionals predicting a much larger transition pressure when the long range dispersive forces are taken into account.

  20. Simulation of the Partially Ionized Negative Hydrogen Plasma

    NASA Astrophysics Data System (ADS)

    Averkin, Sergey; Gatsonis, Nikolaos; Olson, Lynn

    2012-10-01

    A High Pressure Discharge Negative Ion Source (HPDNIS) operating on hydrogen is been under investigation. The Negative Ion Production (NIP) section of the HPDNIS attaches to the 10-100 Torr RF-discharge chamber with a micronozzle and ends with a grid that extracts the negative ion beam. The partially ionized and reacting plasma flow in the NIP section is simulated using an unstructured three-dimensional Direct Simulation Monte Carlo (U3DSMC) code. The NIP section contains a low-pressure plasma that includes H2, vibrationally-rotationally excited H2^*, negative hydrogen atoms H^-, and electrons. Primary reactions in the NIP section are dissociate attachment, H2^*+e->H^0+H^-and electron collisional detachment, e+H^-->H+2e. The U3DSMC computational domain includes the entrance to the NIP nozzle and the extraction grid at the exit. The flow parameters at the entrance are based on conditions in the RF-discharge chamber and are implemented in U3DSMC using a Kinetic-Moment subsonic boundary conditions method. Neutral--neutral, ion-neutral, Coulomb collisions and charge-neutralizing collisions are implemented in U3DSMC using the no time counter method, electron-molecule collisions are treated by the constant timestep method. Simulations cover the regime of operation of the HPDNIS and examine the flow characteristics inside the NIP section.

  1. A Transition to Metallic Hydrogen: Evidence of the Plasma Phase Transition

    NASA Astrophysics Data System (ADS)

    Silvera, Isaac; Zaghoo, Mohamed; Salamat, Ashkan

    The insulator-metal transition in hydrogen is one of the most outstanding problems in condensed matter physics. The high-pressure metallic phase is now predicted to be liquid atomic from T =0 K to very high temperatures. We have conducted measurements of optical properties of hot dense hydrogen in the region of 1.1-1.7 Mbar and up to 2200 K in a diamond anvil cell using pulsed laser heating of the sample. We present evidence in two forms: a plateau in the heating curves (average laser power vs temperature) characteristic of a first-order phase transition with latent heat, and changes in transmittance and reflectance characteristic of a metal for temperatures above the plateau temperature. For thick films the reflectance saturates at ~0.5. The phase line of this transition has a negative slope in agreement with theories of the so-called plasma phase transition. The NSF, Grant DMR-1308641, the DOE Stockpile Stewardship Academic Alliance Program, Grant DE-FG52-10NA29656, and NASA Earth and Space Science Fellowship Program, Award NNX14AP17H supported this research.

  2. Hydrogen production by plasma electrolysis reactor of KOH-ethanol solution

    NASA Astrophysics Data System (ADS)

    Saksono, N.; Batubara, T.; Bismo, S.

    2016-11-01

    Plasma electrolysis has great potential in industrial hydrogen production, chlor-alkali production, and waste water treatment. Plasma electrolysis produces more hydrogen with less energy consumption than hydrocarbon or Faraday electrolysis. This paper investigated the hydrogen production by plasma electrolysis of KOH-ethanol solution at 80 °C and 1 atm. The effects of voltage, KOH solution, ethanol addition, and cathode deep on plasma electrolysis performance were studied. The hydrogen production was analyzed using bubble flow meter and hydrogen analyzer. The electrical energy consumption was measured by a digital multimeter. The effectiveness of plasma electrolysis in terms of hydrogen production was evaluated by comparing it with Faraday Electrolysis. The results showed that hydrogen produced by plasma electrolysis is 149 times higher than the hydrogen produced by Faraday electrolysis. The optimum hydrogen production was 50.71 mmol/min, obtained at 700 V with 0.03 M KOH, 10% vol ethanol and 6.6 cm cathode deep, with energy consumption 1.49 kJ/mmol. The result demonstrates a promising path for hydrogen production by utilizing plasma electrolysis reactor.

  3. Direct synthesis of hydrogen peroxide from plasma-water interactions

    PubMed Central

    Liu, Jiandi; He, Bangbang; Chen, Qiang; Li, Junshuai; Xiong, Qing; Yue, Guanghui; Zhang, Xianhui; Yang, Size; Liu, Hai; Liu, Qing Huo

    2016-01-01

    Hydrogen peroxide (H2O2) is usually considered to be an important reagent in green chemistry since water is the only by-product in H2O2 involved oxidation reactions. Early studies show that direct synthesis of H2O2 by plasma-water interactions is possible, while the factors affecting the H2O2 production in this method remain unclear. Herein, we present a study on the H2O2 synthesis by atmospheric pressure plasma-water interactions. The results indicate that the most important factors for the H2O2 production are the processes taking place at the plasma-water interface, including sputtering, electric field induced hydrated ion emission, and evaporation. The H2O2 production rate reaches ~1200 μmol/h when the liquid cathode is purified water or an aqueous solution of NaCl with an initial conductivity of 10500 μS cm−1. PMID:27917925

  4. Quantum Monte Carlo Studies of Dense Hydrogen and Two-Dimensional Bose Liquids.

    NASA Astrophysics Data System (ADS)

    Magro, William R.

    Quantum Monte Carlo techniques; in their various incarnations, calculate ground state or finite temperature properties of many-body quantum systems. We apply the path-integral Monte Carlo method to hydrogen at densities and temperatures in the regime of cooperative thermal and pressure dissociation, relevant to structural models of the giant planets' interiors. We treat the protons and electrons as quantum particles, thereby avoiding the Born -Oppenheimer approximation. Fermi-Dirac exchange statistics are treated within the fixed-node approximation, with the nodes specified by the free Fermi gas. In the region of molecular dissociation, we observe properties consistent with and suggestive of a first order phase transition with positive density discontinuity (n_{ rm H2}

  5. Quasiparticle energies and excitonic effects in dense solid hydrogen near metallization

    NASA Astrophysics Data System (ADS)

    Dvorak, Marc; Chen, Xiao-Jia; Wu, Zhigang

    2014-07-01

    We investigate the crucial metallization pressure of the Cmca-12 phase of solid hydrogen (H) using many-body perturbation theory within the GW approximation. We consider the effects of self-consistency, plasmon-pole models, and the vertex correction on the quasiparticle band gap (Eg). Our calculations show that self-consistency leads to an increase in Eg by 0.33 eV over the one-shot G0W0 approach. Because of error cancellation between the effects of self-consistency and the vertex correction, the simplest G0W0 method underestimates Eg by only 0.16 eV compared with the prediction of the more accurate GWΓ approach. Employing the plasmon-pole models underestimates Eg by 0.1-0.2 eV compared to the full-frequency numerical integration results. We thus predict a metallization pressure around 280 GPa, instead of 260 GPa predicted previously. Furthermore, we compute the optical absorption including the electron-hole interaction by solving the Bethe-Salpeter equation (BSE). The resulting absorption spectra demonstrate substantial redshifts and enhancement of absorption peaks compared to the calculated spectra neglecting excitonic effects. We find that the exciton binding energy decreases with increasing pressure from 66 meV at 100 GPa to 12 meV at 200 GPa due to the enhanced electronic screening as solid H approaches metallization. Because optical measurements are so important in identifying the structure of solid H, our BSE results should improve agreement between theory and experiment.

  6. Numerical Approach of Interactions of Proton Beams and Dense Plasmas with Quantum-Hydrodynamic/Particle-in-Cell Model

    NASA Astrophysics Data System (ADS)

    Zhang, Ya; Li, Lian; Jiang, Wei; Yi, Lin

    2016-07-01

    A one dimensional quantum-hydrodynamic/particle-in-cell (QHD/PIC) model is used to study the interaction process of an intense proton beam (injection density of 1017 cm-3) with a dense plasma (initial density of ~ 1021 cm-3), with the PIC method for simulating the beam particle dynamics and the QHD model for considering the quantum effects including the quantum statistical and quantum diffraction effects. By means of the QHD theory, the wake electron density and wakefields are calculated, while the proton beam density is calculated by the PIC method and compared to hydrodynamic results to justify that the PIC method is a more suitable way to simulate the beam particle dynamics. The calculation results show that the incident continuous proton beam when propagating in the plasma generates electron perturbations as well as wakefields oscillations with negative valleys and positive peaks where the proton beams are repelled by the positive wakefields and accelerated by the negative wakefields. Moreover, the quantum correction obviously hinders the electron perturbations as well as the wakefields. Therefore, it is necessary to consider the quantum effects in the interaction of a proton beam with cold dense plasmas, such as in the metal films. supported by National Natural Science Foundation of China (Nos. 11405067, 11105057, 11275007)

  7. Analysis of hydrogen plasma in a microwave plasma chemical vapor deposition reactor

    NASA Astrophysics Data System (ADS)

    Shivkumar, G.; Tholeti, S. S.; Alrefae, M. A.; Fisher, T. S.; Alexeenko, A. A.

    2016-03-01

    The aim of this work is to build a numerical model of hydrogen plasma inside a microwave plasma chemical vapor deposition system. This model will help in understanding and optimizing the conditions for the growth of carbon nanostructures. A 2D axisymmetric model of the system is implemented using the finite element high frequency Maxwell solver and the heat transfer solver in COMSOL Multiphysics. The system is modeled to study variation in parameters with reactor geometry, microwave power, and gas pressure. The results are compared with experimental measurements from the Q-branch of the H2 Fulcher band of hydrogen using an optical emission spectroscopy technique. The parameter γ in Füner's model is calibrated to match experimental observations at a power of 500 W and 30 Torr. Good agreement is found between the modeling and experimental results for a wide range of powers and pressures. The gas temperature exhibits a weak dependence on power and a strong dependence on gas pressure. The inclusion of a vertical dielectric pillar that concentrates the plasma increases the maximum electron temperature by 70%, the maximum gas temperature by 50%, and the maximum electron number density by 70% when compared to conditions without the pillar at 500 W and 30 Torr. Experimental observations also indicate intensified plasma with the inclusion of a pillar.

  8. Numerical study of influence of hydrogen backflow on krypton Hall effect thruster plasma focusing

    NASA Astrophysics Data System (ADS)

    Yan, Shilin; Ding, Yongjie; Wei, Liqiu; Hu, Yanlin; Li, Jie; Ning, Zhongxi; Yu, Daren

    2017-03-01

    The influence of backflow hydrogen on plasma plume focusing of a krypton Hall effect thruster is studied via a numerical simulation method. Theoretical analysis indicates that hydrogen participates in the plasma discharge process, changes the potential and ionization distribution in the thruster discharge cavity, and finally affects the plume focusing within a vacuum vessel.

  9. Dielectric function of dense plasmas, their stopping power, and sum rules

    NASA Astrophysics Data System (ADS)

    Arkhipov, Yu. V.; Ashikbayeva, A. B.; Askaruly, A.; Davletov, A. E.; Tkachenko, I. M.

    2014-11-01

    Mathematical, particularly, asymptotic properties of the random-phase approximation, Mermin approximation, and extended Mermin-type approximation of the coupled plasma dielectric function are analyzed within the method of moments. These models are generalized for two-component plasmas. Some drawbacks and advantages of the above models are pointed out. The two-component plasma stopping power is shown to be enhanced with respect to that of the electron fluid.

  10. Measurements of the ion velocity distribution in an ultracold neutral plasma derived from a cold, dense Rydberg gas

    NASA Astrophysics Data System (ADS)

    Bergeson, Scott; Lyon, Mary

    2016-05-01

    We report measurements of the ion velocity distribution in an ultracold neutral plasma derived from a dense, cold Rydberg gas in a MOT. The Rydberg atoms are excited using a resonant two-step excitation pathway with lasers of 4 ns duration. The plasma forms spontaneously and rapidly. The rms width of the ion velocity distribution is determined by measuring laser-induced fluorescence (LIF) of the ions. The measured excitation efficiency is compared with a Monte-Carlo wavefunction calculation, and significant differences are observed. We discuss the conditions for blockaded Rydberg excitation and the subsequent spatial ordering of Rydberg atom domains. While the blockade interaction is greater than the Rabi frequency in portions of the atomic sample, no evidence for spatial ordering is observed. This research is supported in part by the Air Force Office of Scientific Research (Grant No. FA9950-12- 0308) and by the National Science Foundation (Grant No. PHY-1404488).

  11. Design and initial results from a kilojoule level dense plasma focus with hollow anode and cylindrically symmetric gas puff

    NASA Astrophysics Data System (ADS)

    Ellsworth, J. L.; Falabella, S.; Tang, V.; Schmidt, A.; Guethlein, G.; Hawkins, S.; Rusnak, B.

    2014-01-01

    We have designed and built a Dense Plasma Focus (DPF) Z-pinch device using a kJ-level capacitor bank and a hollow anode, and fueled by a cylindrically symmetric gas puff. Using this device, we have measured peak deuteron beam energies of up to 400 keV at 0.8 kJ capacitor bank energy and pinch lengths of ˜6 mm, indicating accelerating fields greater than 50 MV/m. Neutron yields of on the order of 107 per shot were measured during deuterium operation. The cylindrical gas puff system permitted simultaneous operation of DPF with a radiofrequency quadrupole accelerator for beam-into-plasma experiments. This paper describes the machine design, the diagnostic systems, and our first results.

  12. Bounds imposed on the sheath velocity of a dense plasma focus by conservation laws and ionization stability condition

    NASA Astrophysics Data System (ADS)

    Auluck, S. K. H.

    2014-09-01

    Experimental data compiled over five decades of dense plasma focus research are consistent with the snowplow model of sheath propagation, based on the hypothetical balance between magnetic pressure driving the plasma into neutral gas ahead and "wind pressure" resisting its motion. The resulting sheath velocity, or the numerically proportional "drive parameter," is known to be approximately constant for devices optimized for neutron production over 8 decades of capacitor bank energy. This paper shows that the validity of the snowplow hypothesis, with some correction, as well as the non-dependence of sheath velocity on device parameters, have their roots in local conservation laws for mass, momentum, and energy coupled with the ionization stability condition. Both upper and lower bounds on sheath velocity are shown to be related to material constants of the working gas and independent of the device geometry and capacitor bank impedance.

  13. Design and initial results from a kilojoule level Dense Plasma Focus with hollow anode and cylindrically symmetric gas puff.

    PubMed

    Ellsworth, J L; Falabella, S; Tang, V; Schmidt, A; Guethlein, G; Hawkins, S; Rusnak, B

    2014-01-01

    We have designed and built a Dense Plasma Focus (DPF) Z-pinch device using a kJ-level capacitor bank and a hollow anode, and fueled by a cylindrically symmetric gas puff. Using this device, we have measured peak deuteron beam energies of up to 400 keV at 0.8 kJ capacitor bank energy and pinch lengths of ∼6 mm, indicating accelerating fields greater than 50 MV/m. Neutron yields of on the order of 10(7) per shot were measured during deuterium operation. The cylindrical gas puff system permitted simultaneous operation of DPF with a radiofrequency quadrupole accelerator for beam-into-plasma experiments. This paper describes the machine design, the diagnostic systems, and our first results.

  14. Bounds imposed on the sheath velocity of a dense plasma focus by conservation laws and ionization stability condition

    SciTech Connect

    Auluck, S. K. H. E-mail: skauluck@barc.gov.in

    2014-09-15

    Experimental data compiled over five decades of dense plasma focus research are consistent with the snowplow model of sheath propagation, based on the hypothetical balance between magnetic pressure driving the plasma into neutral gas ahead and “wind pressure” resisting its motion. The resulting sheath velocity, or the numerically proportional “drive parameter,” is known to be approximately constant for devices optimized for neutron production over 8 decades of capacitor bank energy. This paper shows that the validity of the snowplow hypothesis, with some correction, as well as the non-dependence of sheath velocity on device parameters, have their roots in local conservation laws for mass, momentum, and energy coupled with the ionization stability condition. Both upper and lower bounds on sheath velocity are shown to be related to material constants of the working gas and independent of the device geometry and capacitor bank impedance.

  15. Magneto-inertial Fusion: An Emerging Concept for Inertial Fusion and Dense Plasmas in Ultrahigh Magnetic Fields

    SciTech Connect

    Thio, Francis Y.C.

    2008-01-01

    An overview of the U.S. program in magneto-inertial fusion (MIF) is given in terms of its technical rationale, scientific goals, vision, research plans, needs, and the research facilities currently available in support of the program. Magneto-inertial fusion is an emerging concept for inertial fusion and a pathway to the study of dense plasmas in ultrahigh magnetic fields (magnetic fields in excess of 500 T). The presence of magnetic field in an inertial fusion target suppresses cross-field thermal transport and potentially could enable more attractive inertial fusion energy systems. A vigorous program in magnetized high energy density laboratory plasmas (HED-LP) addressing the scientific basis of magneto-inertial fusion has been initiated by the Office of Fusion Energy Sciences of the U.S. Department of Energy involving a number of universities, government laboratories and private institutions.

  16. Design and initial results from a kilojoule level dense plasma focus with hollow anode and cylindrically symmetric gas puff

    SciTech Connect

    Ellsworth, J. L. Falabella, S.; Tang, V.; Schmidt, A.; Guethlein, G.; Hawkins, S.; Rusnak, B.

    2014-01-15

    We have designed and built a Dense Plasma Focus (DPF) Z-pinch device using a kJ-level capacitor bank and a hollow anode, and fueled by a cylindrically symmetric gas puff. Using this device, we have measured peak deuteron beam energies of up to 400 keV at 0.8 kJ capacitor bank energy and pinch lengths of ∼6 mm, indicating accelerating fields greater than 50 MV/m. Neutron yields of on the order of 10{sup 7} per shot were measured during deuterium operation. The cylindrical gas puff system permitted simultaneous operation of DPF with a radiofrequency quadrupole accelerator for beam-into-plasma experiments. This paper describes the machine design, the diagnostic systems, and our first results.

  17. Impact of hydrogen isotope species on microinstabilities in helical plasmas

    NASA Astrophysics Data System (ADS)

    Nakata, Motoki; Nunami, Masanori; Sugama, Hideo; Watanabe, Tomo-Hiko

    2016-07-01

    The impact of isotope ion mass on ion-scale and electron-scale microinstabilities such as ion temperature gradient (ITG) mode, trapped electron mode (TEM), and electron temperature gradient (ETG) mode in helical plasmas are investigated by using gyrokinetic Vlasov simulations with a hydrogen isotope and real-mass kinetic electrons. Comprehensive scans for the equilibrium parameters and magnetic configurations clarify the transition from ITG mode to TEM instability, where a significant TEM enhancement is revealed in the case of inward-shifted plasma compared to that in the standard configuration. It is elucidated that the ion-mass dependence on the ratio of the electron-ion collision frequency to the ion transit one, i.e. {ν\\text{ei}}/{ω\\text{ti}}\\propto {{≤ft({{m}\\text{i}}/{{m}\\text{e}}\\right)}1/2} , leads to a stabilization of the TEM for heavier isotope ions. The ITG growth rate indicates a gyro-Bohm-like ion-mass dependence, where the mixing-length estimate of diffusivity yields γ /k\\bot2\\propto m\\text{i}1/2 . On the other hand, a weak isotope dependence of the ETG growth rate is identified. A collisionality scan also reveals that the TEM stabilization by the isotope ions becomes more significant for relatively higher collisionality in a banana regime.

  18. Extremely compact capillary discharge-based soft x-ray lasers and their application to dense plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Rocca, Jorge

    2002-11-01

    Several applications, including the diagnostics of dense plasmas, require bright beams of coherent soft x-ray radiation. Recently significant progress has been made in the development of very compact high brightness soft x-ray lasers with excellent spatial coherence based on fast capillary discharges. Fast discharge-driven compressions in capillary channels produce axially uniform plasmas columns of narrow diameter in which saturated laser amplification is produced by collisional electron excitation of Ne-like ions. With laser pulse energies of several hundred μJ, peak spectral brightness of ˜ 2× 10^25 photons/ (s mm ^2 mrad ^2 0.01% bandwidth) and repetition rate of several Hz, the 46.9 nm the table-top Ne-like Ar capillary discharge laser has been successfully used in several applications. In long capillary plasma columns strong refractive anti-guiding and gain guiding act as an intrinsic mode selection mechanism that makes it possible to achieve essentially full spatial coherence. Such soft x-ray laser beams can probe scale-lengths and plasma densities beyond the limits that plasma refraction and absorption impose on optical laser probes, as initially demonstrated at Lawrence Livermore National Lab with a laboratory-size soft x-ray laser pumped by the Nova laser. With similar brightness, but much higher repetition rate and smaller foot print, the Ne-like Ar capillary discharge laser was used in the first table-top soft x-ray laser plasma diagnostics experiments, that include the shadowgraphy of micro-capillary discharges and interferometry of laser-created plasmas. In combination with a Mach-Zehnder interferometer that uses diffraction gratings as beam splitters it was used to study two-dimensional hydrodynamic effects in laser-created plasmas. Interferograms of plasmas generated at relatively low irradiation intensities (1×10^11- 7×10^12 W cm_2) with 13 ns FWHM duration light pulses revealed the unexpected formation of a concave density profile with a

  19. Ionization Potential Depression in Hot Dense Plasmas Through a Pure Classical Model

    NASA Astrophysics Data System (ADS)

    Calisti, A.; Ferri, S.; Talin, B.

    2015-05-01

    The ionization potential of an ion embedded in a plasma, lowered due to the whole of the charged particles (ions and electrons) interacting with this ion, is the so-called plasma effect. A numerical plasma model based on classical molecular dynamics has been developed recently. It is capable to describe a neutral plasma at equilibrium involving ions of various charge states of the same atom together with electrons. This code is used here to investigate the ionization potential depression (IPD). The study of the IPD is illustrated and discussed for aluminum plasmas at mid and solid density and electron temperatures varying from 50eV to 190eV. The method relies on a sampling of the total potential energy of the electron located at an ion being ionized. The potential energy of such electron results from all of the interacting charged particles interacting with it.

  20. Extended application of Kohn-Sham first-principles molecular dynamics method with plane wave approximation at high energy—From cold materials to hot dense plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, Shen; Wang, Hongwei; Kang, Wei; Zhang, Ping; He, X. T.

    2016-04-01

    An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of electronic structures. This gives an edge to the extended method in the calculation of mixtures of plasmas composed of heterogeneous ions, high-Z dense plasmas, lowering of ionization potentials, X-ray absorption/emission spectra, and opacities, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.

  1. Betatron x-rays from laser plasma accelerators: a new probe for warm dense matter at LCLS

    NASA Astrophysics Data System (ADS)

    Albert, Felicie

    2016-10-01

    Betatron x-ray radiation, driven by electrons from laser-wakefield acceleration, has unique properties to probe high energy density (HED) plasmas and warm dense matter. Betatron radiation is produced when relativistic electrons oscillate in the plasma wake of a laser pulse. Its properties are similar to those of synchrotron radiation, with a 1000 fold shorter pulse. This presentation will focus on the experimental challenges and results related to the development of betatron radiation for x-ray absorption spectroscopy of HED matter at large-scale laser facilities. A detailed presentation of the source mechanisms and characteristics in the blowout regime of laser-wakefield acceleration will be followed by a description of recent experiments performed at the Linac Coherent Light Source (LCLS). At LCLS, we have recently commissioned the betatron x-ray source driven by the MEC short pulse laser (1 J, 40 fs). The source is used as a probe for investigating the X-ray absorption near edge structure (XANES) spectrum at the K- or L-edge of iron and silicon oxide driven to a warm dense matter state (temperature of a few eV and solid densities). The driver is either LCLS itself or an optical laser. These experiments demonstrate the capability to study the electron-ion equilibration mechanisms in warm dense matter with sub-picosecond resolution. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and supported by the Laboratory Directed research and development program under tracking codes 13-LW-076, 16-ERD-041 and by the Office of Fusion Energy Sciences under SCW1476 and SCW1569.

  2. Probing Dense Plasmas Created from Intense Irradiation of Solid Target in the XUV Domain

    SciTech Connect

    Dobosz, S.; Doumy, G.; Stabile, H.; Monot, P.; Bougeard, M.; Reau, F.; Martin, Ph.

    2006-04-07

    In this paper, electronic density and temperature have been inferred from XUV transmission through hot solid-density plasma created by high temporal contrast femtosecond irradiation of thin plastic foil target in the 1018W/cm2 intensity range. High order harmonics generated in pulsed gas jet are used as a probe beam. The initial plasma parameters are determined with an accuracy better than 15% on the 100fs time scale, by comparison of the transmission of two consecutive harmonics.

  3. Observation of Hypervelocity Dust in Dense Supersonic Plasma Flows: Physics and Applications

    SciTech Connect

    Ticos, C. M.; Wang, Z.; Wurden, G. A.; Shukla, P. K.

    2008-10-15

    Synthetic diamond and graphite dust powders with a wide range of sizes, from a few to several tens of microns in diameter were accelerated to velocities up to 4 km/s in vacuum by plasma jet produced in a coaxial gun. Some of the key features of the plasma flow are high density, of the order of 10{sup 22} m{sup -3}, low ion and electron temperatures, of only a few eV, and good collimation over a distance of {approx_equal}2 m due to confinement by the self-generated magnetic field. The main features of this plasma-drag acceleration technique are presented and discussed. From basic science point of view hypervelocity dust is useful for studying the physics of dust interaction with energetic plasma flows at microscopic level. In physical applications, it has been proposed to use hypervelocity dust for diagnostic or control of magnetically confined fusion plasmas. In engineering, hypervelocity dusty plasmas are extensively employed in industrial processes involved in the processing of surfaces.

  4. Frontier of the physics of dense plasmas and planetary interiors: experiments, theory, applications

    SciTech Connect

    Saumon, Didier; Fortney, Jonathan J; Glenzer, Siegfried H; Koenig, Michel; Brambrink, E; Militzer, Burkhard; Valencia, Diana

    2008-01-01

    Recent developments of dynamic x-ray characterization experiments of dense matter are reviewed, with particular emphasis on conditions relevant to interiors of terrestrial and gas giant planets. These studies include characterization of compressed states of matter in light elements by x-ray scattering and imaging of shocked iron by radiography. Several applications of this work are examined. These include the structure of massive 'super-Earth' terrestrial planets around other stars, the 40 known extrasolar gas giants with measured masses and radii, and Jupiter itself, which serves as the benchmark for giant planets.

  5. Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications

    SciTech Connect

    Barbi, E.; Mahan, J.R.; O'brien, W.F.; Wagner, T.C.

    1989-04-01

    The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated. 10 references.

  6. Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications

    NASA Technical Reports Server (NTRS)

    Barbi, E.; Mahan, J. R.; O'Brien, W. F.; Wagner, T. C.

    1989-01-01

    The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated.

  7. Experimental results on the irradiation of nuclear fusion relevant materials at the dense plasma focus ‘Bora’ device

    NASA Astrophysics Data System (ADS)

    Cicuttin, A.; Crespo, M. L.; Gribkov, V. A.; Niemela, J.; Tuniz, C.; Zanolli, C.; Chernyshova, M.; Demina, E. V.; Latyshev, S. V.; Pimenov, V. N.; Talab, A. A.

    2015-06-01

    Samples of materials counted as perspective ones for use in the first-wall and construction elements in nuclear fusion reactors (FRs) with magnetic and inertial plasma confinement (W, Ti, Al, low-activated ferritic steel ‘Eurofer’ and some alloys) were irradiated in the dense plasma focus (DPF) device ‘Bora’ having a bank energy of ⩽5 kJ. The device generates hot dense (T ˜ 1 keV, n ˜ 1019 cm-3) deuterium plasma, powerful plasma streams (v ˜ 3 × 107 cm s-1) and fast (E ˜ 0.1 … 1.0 MeV) deuterons of power flux densities q up to 1010 and 1012 W cm-2 correspondingly. ‘Damage factor’ F = q × τ0.5 ensures an opportunity to simulate radiation loads (predictable for both reactors types) by the plasma/ion streams, which have the same nature and namely those parameters as expected in the FR modules. Before and after irradiation we provided investigations of our samples by means of a number of analytical techniques. Among them we used optical and scanning electron microscopy to understand character and parameters of damageability of the surface layers of the samples. Atomic force microscopy was applied to measure roughness of the surface after irradiation. These characteristics are quite important for understanding mechanisms and values of dust production in FR that may relate to tritium retention and emergency situations in FR facilities. We also applied two new techniques. For the surface we elaborated the portable x-ray diffractometer that combines x-ray single photon detection with high spectroscopic and angular resolutions. For bulk damageability investigations we applied an x-ray microCT system where x-rays were produced by a Hamamatsu microfocus source (150 kV, 500 µA, 5 µm minimum focal spot size). The detector was a Hamamatsu CMOS flat panel coupled to a fibre optic plate under the GOS scintillator. The reconstruction of three-dimensional data was run with Cobra 7.4 and DIGIX CT software while VG Studio Max 2.1, and Amira 5.3 were used for

  8. Weakly nonlinear ion-acoustic excitations in a relativistic model for dense quantum plasma.

    PubMed

    Behery, E E; Haas, F; Kourakis, I

    2016-02-01

    The dynamics of linear and nonlinear ionic-scale electrostatic excitations propagating in a magnetized relativistic quantum plasma is studied. A quantum-hydrodynamic model is adopted and degenerate statistics for the electrons is taken into account. The dispersion properties of linear ion acoustic waves are examined in detail. A modified characteristic charge screening length and "sound speed" are introduced, for relativistic quantum plasmas. By employing the reductive perturbation technique, a Zakharov-Kuznetzov-type equation is derived. Using the small-k expansion method, the stability profile of weakly nonlinear slightly supersonic electrostatic pulses is also discussed. The effect of electron degeneracy on the basic characteristics of electrostatic excitations is investigated. The entire analysis is valid in a three-dimensional as well as in two-dimensional geometry. A brief discussion of possible applications in laboratory and space plasmas is included.

  9. Transport properties of an asymmetric mixture in the dense plasma regime.

    PubMed

    Ticknor, Christopher; Kress, Joel D; Collins, Lee A; Clérouin, Jean; Arnault, Philippe; Decoster, Alain

    2016-06-01

    We study how concentration changes ionic transport properties along isobars-isotherms for a mixture of hydrogen and silver, representative of turbulent layers relevant to inertial confinement fusion and astrophysics. Hydrogen will typically be fully ionized while silver will be only partially ionized but can have a large effective charge. This will lead to very different physical conditions for the H and Ag. Large first principles orbital free molecular dynamics simulations are performed and the resulting transport properties are analyzed. Comparisons are made with transport theory in the kinetic regime and in the coupled regime. The addition of a small amount of heavy element in a light material has a dramatic effect on viscosity and diffusion of the mixture. This effect is explained through kinetic theory as a manifestation of a crossover between classical diffusion and Lorentz diffusion.

  10. Transport properties of an asymmetric mixture in the dense plasma regime

    NASA Astrophysics Data System (ADS)

    Ticknor, Christopher; Kress, Joel D.; Collins, Lee A.; Clérouin, Jean; Arnault, Philippe; Decoster, Alain

    2016-06-01

    We study how concentration changes ionic transport properties along isobars-isotherms for a mixture of hydrogen and silver, representative of turbulent layers relevant to inertial confinement fusion and astrophysics. Hydrogen will typically be fully ionized while silver will be only partially ionized but can have a large effective charge. This will lead to very different physical conditions for the H and Ag. Large first principles orbital free molecular dynamics simulations are performed and the resulting transport properties are analyzed. Comparisons are made with transport theory in the kinetic regime and in the coupled regime. The addition of a small amount of heavy element in a light material has a dramatic effect on viscosity and diffusion of the mixture. This effect is explained through kinetic theory as a manifestation of a crossover between classical diffusion and Lorentz diffusion.

  11. Electrical conductivity of dense Al, Ti, Fe, Ni, Cu, Mo, Ta, and W plasmas.

    PubMed

    DeSilva, A W; Vunni, G B

    2011-03-01

    We report measurements of electrical conductivity of eight metals in the plasma state at densities ranging from 0.002 to 0.5 times solid density, and with internal energy from 2 to 30 kJ/gm. Data are presented as functions of internal energy and specific volume. Conductivity is observed to fall as the plasma expands for fixed internal energy, and for all but tantalum and titanium shows a minimum at approximately 0.01 times solid density, followed by an increase as the density decreases further.

  12. The influence of the local volume fluctuations on the equation-of-state of hot and dense plasmas

    NASA Astrophysics Data System (ADS)

    Salzmann, David; Fisher, Dima; Barshalom, Avraham; Oreg, Joseph

    2008-04-01

    Generally, equation-of-state (EOS) of hot and dense plasmas is computed under the assumption that there is a constant volume available to every ion/atom in the plasma. In the present paper we combined two recently developed models to evaluate the influence of local density fluctuations around the ions on the corresponding EOS. The first of these is the so-called Ion Ellipsoid Model (IEM). IEM assumes that the local volume of the ion is a 3-dimensional ellipsoidal enclosure. Full description of the model is given in Ref. [1]. From IEM semi-empirical formulas were derived for the ions volume distribution function [1] for 0<γ<16, where γ is the plasma coupling constant. The EOS was computed by means of the EOSTA model [2], that combines and extends the STA and INFERNO models to calculate opacities and EOS on the same footing. We will describe the model and present preliminary results indicating the effect of the volume fluctuations around the ions on EOS results.

  13. Temperature of hydrogen radio frequency plasma under dechlorination process of polychlorinated biphenyls

    NASA Astrophysics Data System (ADS)

    Inada, Y.; Abe, K.; Kumada, A.; Hidaka, K.; Amano, K.; Itoh, K.; Oono, T.

    2014-10-01

    It has been reported that RF (radio frequency) hydrogen plasmas promote the dechlorination process of PCBs (polychlorinated biphenyls) under irradiation of MW (microwave). A relative emission intensity spectroscope system was used for single-shot imaging of two-dimensional temperature distributions of RF hydrogen plasmas generated in chemical solutions with several mixing ratios of isopropyl alcohol (IPA) and insulation oil under MW irradiation. Our experimental results showed that the plasma generation frequencies for the oil-contaminating solutions were higher than that for the pure IPA solution. In addition, the plasma temperature in the compound liquids including both oil and IPA was higher than that in the pure IPA and oil solutions. A combination of the plasma temperature measurements and plasma composition analysis indicated that the hydrogen radicals generated in a chemical solution containing the equal volumes of IPA and oil were almost the same amounts of H and H+, while those produced in the other solutions were mainly H.

  14. Temperature of hydrogen radio frequency plasma under dechlorination process of polychlorinated biphenyls

    SciTech Connect

    Inada, Y. Abe, K.; Kumada, A.; Hidaka, K.; Amano, K.; Itoh, K.; Oono, T.

    2014-10-27

    It has been reported that RF (radio frequency) hydrogen plasmas promote the dechlorination process of PCBs (polychlorinated biphenyls) under irradiation of MW (microwave). A relative emission intensity spectroscope system was used for single-shot imaging of two-dimensional temperature distributions of RF hydrogen plasmas generated in chemical solutions with several mixing ratios of isopropyl alcohol (IPA) and insulation oil under MW irradiation. Our experimental results showed that the plasma generation frequencies for the oil-contaminating solutions were higher than that for the pure IPA solution. In addition, the plasma temperature in the compound liquids including both oil and IPA was higher than that in the pure IPA and oil solutions. A combination of the plasma temperature measurements and plasma composition analysis indicated that the hydrogen radicals generated in a chemical solution containing the equal volumes of IPA and oil were almost the same amounts of H and H{sup +}, while those produced in the other solutions were mainly H.

  15. Effect of methane concentration in hydrogen plasma on hydrogen impurity incorporation in thick large-grained polycrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Tang, C. J.; Fernandes, A. J. S.; Jiang, X. F.; Pinto, J. L.; Ye, H.

    2015-09-01

    We investigate the impact of methane concentration in hydrogen plasma on the growth of large-grained polycrystalline diamond (PCD) films and its hydrogen impurity incorporation. The diamond samples were produced using high CH4 concentration in H2 plasma and high power up to 4350 W and high pressure (either 105 or 110 Torr) in a microwave plasma chemical vapor deposition (MPCVD) system. The thickness of the free-standing diamond films varies from 165 μm to 430 μm. Scanning electron microscopy (SEM), micro-Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the morphology, crystalline and optical quality of the diamond samples, and bonded hydrogen impurity in the diamond films, respectively. Under the conditions employed here, when methane concentration in the gas phase increases from 3.75% to 7.5%, the growth rate of the PCD films rises from around 3.0 μm/h up to 8.5 μm/h, and the optical active bonded hydrogen impurity content also increases more than one times, especially the two CVD diamond specific H related infrared absorption peaks at 2818 and 2828 cm-1 rise strongly; while the crystalline and optical quality of the MCD films decreases significantly, namely structural defects and non-diamond carbon phase content also increases a lot with increasing of methane concentration. Based on the results, the relationship between methane concentration and diamond growth rate and hydrogen impurity incorporation including the form of bonded infrared active hydrogen impurity in CVD diamonds was analyzed and discussed. The effect of substrate temperature on diamond growth was also briefly discussed. The experimental findings indicate that bonded hydrogen impurity in CVD diamond films mainly comes from methane rather than hydrogen in the gas source, and thus can provide experimental evidence for the theoretical study of the standard methyl species dominated growth mechanism of CVD diamonds grown with methane/hydrogen mixtures.

  16. Central structure of low-n Balmer lines in dense plasmas

    NASA Technical Reports Server (NTRS)

    Hey, J. D.; Griem, H. R.

    1975-01-01

    The investigation reported is concerned with disagreements between the computations of Kepple and Griem (1968) and the results of calculations based upon the 'unified theory' proposed by Vidal et al. (1973). Experiments were conducted with a high-pressure electromagnetically driven shock tube as the plasma source. The diagnostic methods used are discussed along with the experimental results and their significance.

  17. K-(alpha) X-ray Thomson Scattering From Dense Plasmas

    SciTech Connect

    Kritcher, A L; Neumayer, P; Castor, J; Doppner, T; Falcone, R W; Landen, O L; Lee, H J; Lee, R W; Morse, E C; Ng, A; Pollaine, S; Price, D; Glenzer, S H

    2009-05-07

    Spectrally resolved Thomson scattering using ultra-fast K-{alpha} x-rays has measured the compression and heating of shocked compressed matter. The evolution and coalescence of two shock waves traveling through a solid density LiH target were characterized by the elastic scattering component. The density and temperature at shock coalescence, 2.2 eV and 1.7 x 10{sup 23}cm{sup -3}, were determined from the plasmon frequency shift and the relative intensity of the elastic and inelastic scattering features in the collective scattering regime. The observation of plasmon scattering at coalescence indicates a transition to the dense metallic state in LiH. The density and temperature regimes accessed in these experiments are relevant for inertial confinement fusion experiments and for the study of planetary formation.

  18. Space hardware compatibility tests with hydrogen peroxide gas plasma sterilization

    NASA Astrophysics Data System (ADS)

    Faye, Delphine; Aguila, Alexandre; Debus, Andre; Remaury, Stephanie; Nabarra, Pascale; Darbord, Jacques C.; Soufflet, Caroline; Destrez, Philippe; Coll, Patrice; Coscia, David

    The exploration of the Solar System shall comply with planetary protection requirements handled presently by the Committee of Space Research (COSPAR). The goal of planetary protection is to protect celestial bodies from terrestrial contamination and also to protect the Earth environment from an eventual contamination carried by return samples or by space systems. For project teams, avoiding the biological contamination of other Solar System bodies such as Mars imposes to perform unusual tasks at technical and operational constraints point of view. The main are the reduction of bioburden on space hardware, the sterile integration of landers, the control of the biological cleanliness and the limitation of crash probability. In order to reduce the bioburden on spacecraft, the use of qualified sterilization processes may be envisaged. Since 1992 now, with the Mars96 mission, one of the most often used is the Sterrad(R) process working with hydrogen peroxide gas plasma. In the view of future Mars exploration programs, after tests performed in the frame of previous missions, a new test campaign has been performed on thermal coatings and miscellaneous materials coming from an experiment in order to assess the compatibility of space hardware and material with this sterilization process.

  19. A common genetic mechanism determines plasma apolipoprotein B levels and dense LDL subfraction distribution in familial combined hyperlipidemia.

    PubMed Central

    Juo, S H; Bredie, S J; Kiemeney, L A; Demacker, P N; Stalenhoef, A F

    1998-01-01

    Familial combined hyperlipidemia (FCH) is a common lipid disorder characterized by elevations of plasma cholesterol and/or triglyceride in first-degree relatives. A predominance of small, dense LDL particles and elevated apolipoprotein B (apoB) levels is commonly found in members of FCH families. Many studies have investigated the genetic mechanisms determining individuals' lipid levels, in FCH families. Previously, we demonstrated a major gene effect on LDL particle size and codominant Mendelian inheritance involved in determination of apoB levels in a sample of 40 well-defined FCH families. An elevation of apoB levels is associated metabolically with a predominance of small, dense LDL particles in FCH. To establish whether a common gene regulates both traits, we conducted a bivariate genetic analysis to test the hypothesis of a common genetic mechanism. In this study, we found that 66% of the total phenotypic correlation is due to shared genetic components. Further bivariate segregation analysis suggested that both traits share a common major gene plus individual polygenic components. This common major gene explains 37% of the variance of adjusted LDL particle size and 23% of the variance of adjusted apoB levels. Our study suggests that a major gene that has pleiotropic effects on LDL particle size and apoB levels may be the gene underlying FCH in the families we studied. PMID:9683593

  20. Hydrogen Balmer Series Self-Absorption Measurement in Laser-Induced Air Plasma

    NASA Astrophysics Data System (ADS)

    Gautam, Ghaneshwar; Parigger, Christian

    2015-05-01

    In experimental studies of laser-induced plasma, we use focused Nd:YAG laser radiation to generate optical breakdown in laboratory air. A Czerny-Turner type spectrometer and an ICCD camera are utilized to record spatially and temporally resolved spectra. Time-resolved spectroscopy methods are employed to record plasma dynamics for various time delays in the range of 0.300 microsecond to typically 10 microsecond after plasma initiation. Early plasma emission spectra reveal hydrogen alpha and ionized nitrogen lines for time delays larger than 0.3 microsecond, the hydrogen beta line emerges from the free-electron background radiation later in the plasma decay for time delays in excess of 1 microsecond. The self-absorption analyses include comparisons of recorded data without and with the use of a doubling mirror. The extent of self-absorption of the hydrogen Balmer series is investigated for various time delays from plasma generation. There are indications of self-absorption of hydrogen alpha by comparison with ionized nitrogen lines at a time delay of 0.3 microsecond. For subsequent time delays, self-absorption effects on line-widths are hardly noticeable, despite the fact of the apparent line-shape distortions. Of interest are comparisons of inferred electron densities from hydrogen alpha and hydrogen beta lines as the plasma decays, including assessments of spatial variation of electron density.

  1. Detailed analysis of hollow ions spectra from dense matter pumped by X-ray emission of relativistic laser plasma

    NASA Astrophysics Data System (ADS)

    Hansen, S. B.; Colgan, J.; Faenov, A. Ya.; Abdallah, J.; Pikuz, S. A.; Skobelev, I. Yu.; Wagenaars, E.; Booth, N.; Culfa, O.; Dance, R. J.; Tallents, G. J.; Evans, R. G.; Gray, R. J.; Kaempfer, T.; Lancaster, K. L.; McKenna, P.; Rossall, A. K.; Schulze, K. S.; Uschmann, I.; Zhidkov, A. G.; Woolsey, N. C.

    2014-03-01

    X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.

  2. Detailed analysis of hollow ions spectra from dense matter pumped by X-ray emission of relativistic laser plasma

    SciTech Connect

    Hansen, S. B. E-mail: anatolyf@hotmail.com; Colgan, J.; Abdallah, J.; Faenov, A. Ya. E-mail: anatolyf@hotmail.com; Pikuz, S. A.; Skobelev, I. Yu.; Wagenaars, E.; Culfa, O.; Dance, R. J.; Tallents, G. J.; Rossall, A. K.; Woolsey, N. C.; Booth, N.; Lancaster, K. L.; Evans, R. G.; Gray, R. J.; McKenna, P.; Kaempfer, T.; Schulze, K. S.; Uschmann, I.; and others

    2014-03-15

    X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.

  3. Effect of nearest-neighbor ions on excited ionic states, emission spectra, and line profiles in hot and dense plasmas

    NASA Technical Reports Server (NTRS)

    Salzmann, D.; Stein, J.; Goldberg, I. B.; Pratt, R. H.

    1991-01-01

    The effect of the cylindrical symmetry imposed by the nearest-neighbor ions on the ionic levels and the emission spectra of a Li-like Kr ion immersed in hot and dense plasmas is investigated using the Stein et al. (1989) two-centered model extended to include computations of the line profiles, shifts, and widths, as well as the energy-level mixing and the forbidden transition probabilities. It is shown that the cylindrical symmetry mixes states with different orbital quantum numbers l, particularly for highly excited states, and, thereby, gives rise to forbidden transitions in the emission spectrum. Results are obtained for the variation of the ionic level shifts and mixing coefficients with the distance to the nearest neighbor. Also obtained are representative computed spectra that show the density effects on the spectral line profiles, shifts, and widths, and the forbidden components in the spectrum.

  4. A two-dimensional model of the hydrogen plasma for a laser powered rocket

    NASA Technical Reports Server (NTRS)

    Keefer, D.; Crowder, H.; Elkins, R.

    1982-01-01

    A two-dimensional, closed-form model originally developed by Batteh and Keefer (1974) is modified and applied to the absorption of laser radiation by a hydrogen plasma. The model is used to predict the power absorbed by plasmas at one- and ten-atmosphere pressure as a function of laser beam radius. Predicted isotherms are given for one- and ten-atmosphere plasmas, together with thermal loading of the absorption chamber wall. The model is also used in predicting the laser power required to sustain a hydrogen plasma as a function of the absorption coefficient.

  5. Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

    SciTech Connect

    Čeřovský, M.; Khun, J.; Rusová, K.; Scholtz, V.; Soušková, H.

    2013-09-15

    The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperature plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials.

  6. Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Čeřovský, M.; Khun, J.; Rusová, K.; Scholtz, V.; Soušková, H.

    2013-09-01

    The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperature plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials.

  7. Dense Helical Electron Bunch Generation in Near-Critical Density Plasmas with Ultrarelativistic Laser Intensities.

    PubMed

    Hu, Ronghao; Liu, Bin; Lu, Haiyang; Zhou, Meilin; Lin, Chen; Sheng, Zhengming; Chen, Chia-erh; He, Xiantu; Yan, Xueqing

    2015-10-27

    The mechanism for emergence of helical electron bunch(HEB) from an ultrarelativistic circularly polarized laser pulse propagating in near-critical density(NCD) plasma is investigated. Self-consistent three-dimensional(3D) Particle-in-Cell(PIC) simulations are performed to model all aspects of the laser plasma interaction including laser pulse evolution, electron and ion motions. At a laser intensity of 10(22) W/cm(2), the accelerated electrons have a broadband spectrum ranging from 300 MeV to 1.3 GeV, with the charge of 22 nano-Coulombs(nC) within a solid-angle of 0.14 Sr. Based on the simulation results, a phase-space dynamics model is developed to explain the helical density structure and the broadband energy spectrum.

  8. Recombination of ions of a dense ion plasma in a fluorine atmosphere

    NASA Astrophysics Data System (ADS)

    Lankin, A. V.

    2016-08-01

    A new effect leading to the slowing of recombination in a weakly nonideal ion plasma is considered. The solvation of ions is included in the explanation of the results from studying a gas discharge afterglow in a fluorine atmosphere. It is shown that recombination in such a system is slowed in comparison to the standard relationships for ideal plasma. The formation and composition of cluster ions in such a medium are considered. The relationship between the variation in the kinetics of recombination and the course of the process according to a complicated mechanism with the intermediate formation of metastable cluster pairs is established. A quantitative model is built and a formula allowing us to describe the recombination rate over a wide range of parameters of the medium is obtained. It is shown that the proposed model is in good agreement with the experimental data.

  9. The effect of degeneracy parameter on Weibel instability in dense plasma

    SciTech Connect

    Mahdavi, M.; Khodadadi Azadboni, F.

    2013-12-15

    In this paper, the role of degeneracy parameter, in both directions parallel and perpendicular with propagation direction of the laser beam in plasma, on the growth rate of Weibel instability, is studied. Calculations show that with the temperature anisotropy, β = T{sub ∥}/T{sub ⊥} = 0.2 and a 0.75 times reduction of the degeneracy parameter, the increased rate of the the Weibel instability growth rate is 72%. The degeneracy required for minimal growth rate in interaction laser plasma with a density of 1.2 × 10{sup 32}m{sup −3}, is larger than 3. The reduction of temperature and the degeneracy parameter of plasma in parallel direction will also increase growth rate about 30% more than incrossing degeneracy parameter in transverse direction. With the minimum pressure costs of cold compression, subsequent degeneracy parameters, and the minimum value of electron quiver energy, we can expect growth rate of Weibel instability order 0.01.

  10. Filamentary structures in dense plasma focus: Current filaments or vortex filaments?

    SciTech Connect

    Soto, Leopoldo Pavez, Cristian; Moreno, José; Castillo, Fermin; Veloso, Felipe; Auluck, S. K. H.

    2014-07-15

    Recent observations of an azimuthally distributed array of sub-millimeter size sources of fusion protons and correlation between extreme ultraviolet (XUV) images of filaments with neutron yield in PF-1000 plasma focus have re-kindled interest in their significance. These filaments have been described variously in literature as current filaments and vortex filaments, with very little experimental evidence in support of either nomenclature. This paper provides, for the first time, experimental observations of filaments on a table-top plasma focus device using three techniques: framing photography of visible self-luminosity from the plasma, schlieren photography, and interferometry. Quantitative evaluation of density profile of filaments from interferometry reveals that their radius closely agrees with the collision-less ion skin depth. This is a signature of relaxed state of a Hall fluid, which has significant mass flow with equipartition between kinetic and magnetic energy, supporting the “vortex filament” description. This interpretation is consistent with empirical evidence of an efficient energy concentration mechanism inferred from nuclear reaction yields.

  11. Emission of fast non-Maxwellian hydrogen atoms in low-density laboratory plasma

    NASA Astrophysics Data System (ADS)

    Brandt, Christian; Marchuk, Oleksandr; Pospieszczyk, Albrecht; Dickheuer, Sven

    2017-03-01

    The source of strong and broad emission of the Balmer-α line in mixed plasmas of hydrogen (or deuterium) and noble gases in front of metallic surfaces is a subject of controversial discussion of many plasma types. In this work the excitation source of the Balmer lines is investigated by means of optical emission spectroscopy in the plasma device PSI-2. Neutral fast non-Maxwellian hydrogen atoms are produced by acceleration of hydrogen ions towards an electrode immersed into the plasma. By variation of the electrode potential the energy of ions and in turn of reflected fast atoms can be varied in the range of 40-300 eV. The fast atoms in front of the electrode are observed simultaneously by an Echelle spectrometer (0.001 nm/channel) and by an imaging spectrometer (0.01 nm/channel) up to few cm in the plasma. Intense excitation channels of the Balmer lines are observed when hydrogen is mixed with argon or with krypton. Especially in Ar-H and Ar-D mixed plasmas the emission of fast hydrogen atoms is very strong. Intermixing hydrogen with other noble gases (He, Ne or Xe) one observes the same effect however the emission is one order of magnitude less compared to Kr-H or Kr-D plasmas. It is shown, that the key process, impacting this emission, is the binary collision between the fast neutral hydrogen atom and the noble gas atom. Two possible sources of excitation are discussed in details: one is the excitation of hydrogen atoms by argon atoms in the ground state and the second one is the process of the so-called excitation transfer between the metastable states of noble gases and hydrogen. In the latter case the atomic data for excitation of Balmer lines are still not available in literature. Further experimental investigations are required to conclude on the source process of fast atom emission.

  12. Deposition of a-SiC:H using organosilanes in an argon/hydrogen plasma

    SciTech Connect

    Maya, L.

    1993-12-01

    Selected organosilanes were examined as precursors for the deposition of amorphous hydrogenated silicon carbide in an argon/hydrogen plasma. Effect of process variables on the quality of the films was established by means of FTIR, Auger spectroscopy, XPS, XRD, chemical analysis, and weight losses upon pyrolysis. For a given power level there is a limiting feeding rate of the precursor under which operation of the system is dominated by thermodynamics and leads to high quality silicon carbide films that are nearly stoichiometric and low in hydrogen. Beyond that limit, carbosilane polymer formation and excessive hydrogen incorporation takes place. The hydrogen content of the plasma affects the deposition rate and the hydrogen content of the film. In the thermodynamically dominated regime the nature of the precursor has no effect on the quality of the film, it affects only the relative utilization efficiency.

  13. Optimum plasma grid bias for a negative hydrogen ion source operation with Cs

    SciTech Connect

    Bacal, Marthe; Sasao, Mamiko; Wada, Motoi; McAdams, Roy

    2016-02-15

    The functions of a biased plasma grid of a negative hydrogen (H{sup −}) ion source for both pure volume and Cs seeded operations are reexamined. Proper control of the plasma grid bias in pure volume sources yields: enhancement of the extracted negative ion current, reduction of the co-extracted electron current, flattening of the spatial distribution of plasma potential across the filter magnetic field, change in recycling from hydrogen atomic/molecular ions to atomic/molecular neutrals, and enhanced concentration of H{sup −} ions near the plasma grid. These functions are maintained in the sources seeded with Cs with additional direct emission of negative ions under positive ion and neutral hydrogen bombardment onto the plasma electrode.

  14. Uniform Atomic Layer Deposition of Al2O3 on Graphene by Reversible Hydrogen Plasma Functionalization

    PubMed Central

    2017-01-01

    A novel method to form ultrathin, uniform Al2O3 layers on graphene using reversible hydrogen plasma functionalization followed by atomic layer deposition (ALD) is presented. ALD on pristine graphene is known to be a challenge due to the absence of dangling bonds, leading to nonuniform film coverage. We show that hydrogen plasma functionalization of graphene leads to uniform ALD of closed Al2O3 films down to 8 nm in thickness. Hall measurements and Raman spectroscopy reveal that the hydrogen plasma functionalization is reversible upon Al2O3 ALD and subsequent annealing at 400 °C and in this way does not deteriorate the graphene’s charge carrier mobility. This is in contrast with oxygen plasma functionalization, which can lead to a uniform 5 nm thick closed film, but which is not reversible and leads to a reduction of the charge carrier mobility. Density functional theory (DFT) calculations attribute the uniform growth on both H2 and O2 plasma functionalized graphene to the enhanced adsorption of trimethylaluminum (TMA) on these surfaces. A DFT analysis of the possible reaction pathways for TMA precursor adsorption on hydrogenated graphene predicts a binding mechanism that cleans off the hydrogen functionalities from the surface, which explains the observed reversibility of the hydrogen plasma functionalization upon Al2O3 ALD.

  15. Thermodynamical Study on Production of Acetylene from Coal Pyrolysis in Hydrogen Plasma

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Guo, Wenkang; Yuan, Xingqiu; Zhao, Taize

    2006-05-01

    The chemical thermodynamic equilibrium of acetylene production by coal pyrolysis in hydrogen plasma was studied. The thermodynamic equilibrium is obtained by using the method of free energy. Calculated results show that the hydrogen concentration in the equilibrium system is very important for the acetylene production by coal conversion and the energy consumption for the production of acetylene per-kilogram strongly depends on the hydrogen concentration and the temperature.

  16. Supersonic propagation of ionization waves in an under-dense, laser-produced plasma

    SciTech Connect

    Constantin, C; Back, C A; Fournier, K B; Gregori, G; Landen, O L; Glenzer, S H; Dewald, E L; Miller, M C

    2004-10-22

    We observe a laser-driven supersonic ionization wave heating a mm-scale plasma of sub-critical density up to 2-3 keV electron temperatures. Propagation velocities initially 10 times the sound speed were measured by means of time-resolved x-ray imaging diagnostics. The measured ionization wave trajectory is modeled analytically and by a 2D radiation-hydrodynamics code. The comparison to the modeling suggests that nonlocal heat transport effects may contribute to the attenuation of the heat wave propagation.

  17. Relevant ion time scales for electron impact processes of atoms in dense plasmas

    SciTech Connect

    Murillo, M.S.

    1997-12-31

    In this paper a new model for treating collisional atomic processes has been presented. This model simultaneously and self-consistently treats electron and ion processes. For transitions frequencies above the ion plasma frequency, it is argued that little ion motion occurs although the interaction is still strong; the ion microfield perturbs the atom. The electron impact processes may still be described by a DSF between levels of the perturbed atoms, suggesting the name Microfield Stochastic Model (MSM) for this method. Future work will be directed towards refining some of the approximations used here for application to realistic systems.

  18. Electron-ion relaxation in a dense plasma. [supernovae core physics

    NASA Technical Reports Server (NTRS)

    Littleton, J. E.; Buchler, J.-R.

    1974-01-01

    The microscopic physics of the thermonuclear runaway in highly degenerate carbon-oxygen cores is investigated to determine if and how a detonation wave is generated. An expression for the electron-ion relaxation time is derived under the assumption of large degeneracy and extreme relativity of the electrons in a two-temperature plasma. Since the nuclear burning time proves to be several orders of magnitude shorter than the relaxation time, it is concluded that in studying the structure of the detonation wave the electrons and ions must be treated as separate fluids.

  19. Application of linear response theory to magnetotransport properties of dense plasmas

    SciTech Connect

    Adams, J. R.; Redmer, R.; Reinholz, H.

    2010-03-15

    Linear response theory, as developed within the Zubarev formalism, is a quantum statistical approach for describing systems out of but close to equilibrium, which has been successfully applied to a wide variety of plasmas in an external electric field and/or containing a temperature gradient. We present here an extension of linear response theory to include the effects of an external magnetic field. General expressions for the complete set of relevant transport properties are given. In particular, the Hall effect and the influence of a magnetic field on the dc electrical conductivity are discussed. Low-density limits including electron-electron scattering are presented as well as results for arbitrary degeneracy.

  20. Electrical Conductivity of Dense Al, Ti, Fe, Ni, Cu, Mo, Ta, and W Plasmas

    DTIC Science & Technology

    2011-06-01

    conductivity measurements previously reported by the author and co- workers [1–5] required the use of tabulated equations of state from the SESAME library...Thermophys. 26, 1137 (2005). [6] S. P. Lyon and J. D. Johnson, “ Sesame : the Los Alamos National Laboratory Equation of State Database,” Report No. LA-UR-92...eight metals in the plasma state at densities ranging from 0.002 to 0.5 times solid density, and with internal energy from 2 to 30 kJ/gm. Data are

  1. Plasma test on industrial diamond powder in hydrogen and air for fracture strength study

    NASA Astrophysics Data System (ADS)

    Chary, Rohit Asuri Sudharshana

    Diamonds are the most precious material all over the world. Ever since their discovery, the desire for natural diamonds has been great; recently, the demand has steeply increased, leading to scarcity. For example, in 2010, diamonds worth $50 billion were marketed. This increased demand has led to discovering alternative sources to replace diamonds. The diamond, being the hardest material on earth, could be replaced with no other material except another diamond. Thus, the industrial or synthetic diamond was invented. Because of extreme hardness is one of diamond's properties, diamonds are used in cutting operations. The fracture strength of diamond is one of the crucial factors that determine its life time as a cutting tool. Glow discharge is one of the techniques used for plasma formation. The glow discharge process is conducted in a vacuum chamber by ionizing gas atoms. Ions penetrate into the atomic structure, ejecting a secondary electron. The objective of this study is to determine the change in fracture strength of industrial diamond powder before and after plasma treatment. This study focuses mainly on the change in crystal defects and crushing strength (CS) of industrial diamond powder after the penetration of hydrogen gas, air and hydrogen-air mixture ions into the sample powder. For this study, an industrial diamond powder sample of 100 carats weight, along with its average fracture strength value was received from Engis Corporation, Illinois. The sample was divided into parts, each weighing 10-12 carats. At the University of Nevada, Las Vegas (UNLV), a plasma test was conducted on six sample parts for a total of 16 hours on each part. The three gas types mentioned above were used during plasma tests, with the pressure in vacuum chamber between 200 mTorr and 2 Torr. The plasma test on four sample parts was in the presence of hydrogen-air mixture. The first sample had chamber pressures between 200 mTorr and 400 mTorr. The remaining three samples had chamber

  2. Bayesian inference of x-ray diffraction spectra from warm dense matter with the one-component-plasma model

    NASA Astrophysics Data System (ADS)

    Clérouin, Jean; Desbiens, Nicolas; Dubois, Vincent; Arnault, Philippe

    2016-12-01

    We show that the Bayesian inference of recently measured x-ray diffraction spectra from laser-shocked aluminum [L. B. Fletcher et al., Nat. Photon. 9, 274 (2015), 10.1038/nphoton.2015.41] with the one-component-plasma (OCP) model performs remarkably well at estimating the ionic density and temperature. This statistical approach requires many evaluations of the OCP static structure factor, which were done using a recently derived analytic fit. The atomic form factor is approximated by an exponential function in the diffraction window of the first peak. The electronic temperature is then estimated from a comparison of this approximated form factor with the electronic structure of an average atom model. Out-of-equilibrium states, with electrons hotter than ions, are diagnosed for the spectra obtained early after the pump, whereas at a late time delay the plasma is at thermal equilibrium. Apart from the present findings, this OCP-based modeling of warm dense matter has an important role to play in the interpretation of x-ray Thomson scattering measurements currently performed at large laser facilities.

  3. Dense GeV electron-positron pairs generated by lasers in near-critical-density plasmas.

    PubMed

    Zhu, Xing-Long; Yu, Tong-Pu; Sheng, Zheng-Ming; Yin, Yan; Turcu, Ion Cristian Edmond; Pukhov, Alexander

    2016-12-14

    Pair production can be triggered by high-intensity lasers via the Breit-Wheeler process. However, the straightforward laser-laser colliding for copious numbers of pair creation requires light intensities several orders of magnitude higher than possible with the ongoing laser facilities. Despite the numerous proposed approaches, creating high-energy-density pair plasmas in laboratories is still challenging. Here we present an all-optical scheme for overdense pair production by two counter-propagating lasers irradiating near-critical-density plasmas at only ∼10(22) W cm(-2). In this scheme, bright γ-rays are generated by radiation-trapped electrons oscillating in the laser fields. The dense γ-photons then collide with the focused counter-propagating lasers to initiate the multi-photon Breit-Wheeler process. Particle-in-cell simulations indicate that one may generate a high-yield (1.05 × 10(11)) overdense (4 × 10(22) cm(-3)) GeV positron beam using 10 PW scale lasers. Such a bright pair source has many practical applications and could be basis for future compact high-luminosity electron-positron colliders.

  4. Dense GeV electron-positron pairs generated by lasers in near-critical-density plasmas

    NASA Astrophysics Data System (ADS)

    Zhu, Xing-Long; Yu, Tong-Pu; Sheng, Zheng-Ming; Yin, Yan; Turcu, Ion Cristian Edmond; Pukhov, Alexander

    2016-12-01

    Pair production can be triggered by high-intensity lasers via the Breit-Wheeler process. However, the straightforward laser-laser colliding for copious numbers of pair creation requires light intensities several orders of magnitude higher than possible with the ongoing laser facilities. Despite the numerous proposed approaches, creating high-energy-density pair plasmas in laboratories is still challenging. Here we present an all-optical scheme for overdense pair production by two counter-propagating lasers irradiating near-critical-density plasmas at only ~1022 W cm-2. In this scheme, bright γ-rays are generated by radiation-trapped electrons oscillating in the laser fields. The dense γ-photons then collide with the focused counter-propagating lasers to initiate the multi-photon Breit-Wheeler process. Particle-in-cell simulations indicate that one may generate a high-yield (1.05 × 1011) overdense (4 × 1022 cm-3) GeV positron beam using 10 PW scale lasers. Such a bright pair source has many practical applications and could be basis for future compact high-luminosity electron-positron colliders.

  5. The Dense Plasma Focus Opportunities in Detection of Hidden Objects by Using Nanosecond Impulse Neutron Inspection System (NINIS)

    NASA Astrophysics Data System (ADS)

    Gribkov, V.; Dubrovsky, A.; Karpiński, L.; Miklaszewski, R.; Paduch, M.; Scholz, M.; StrzyŻewski, P.; Tomaszewski, K.

    2006-12-01

    Dense Plasma Focus device is proposed for use as a neutron source to generate very powerful pulses of neutrons in the nanosecond (ns) range of its duration. Our devices PF-6, recently put into operation at the Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland, and PF-10 belonging to the Institute for Theoretical and Experimental Physics, Moscow, Russia, have energy storages in its capacitor banks 7.4 kJ and 13 kJ as a maximum. Operated with the DPF chambers of a special design they have a current maximum up to ˜760 kA with a quarter period of the discharge equal to 1 microsecond. They generate circa 109 of 2.5-MeV neutrons in one pulse of ≅ 10-ns duration when working with deuterium, what permit to expect 1011 14-MeV neutrons at their operation with DT-mixture. This feature gives a principal possibility to create a "single-shot detection system" for interrogation of hidden objects. It means that all necessary information will be received during a single bright pulse of neutrons having duration in a nanosecond range by means of the time-of-flight technique with a short flight base. It might be a base for the creation of the Nanosecond Impulse Neutron Inspection System (NINIS). These characteristics of the neutron source open a number of opportunities while interrogation time in this case would now depend only on the data-processing system.

  6. Dense GeV electron–positron pairs generated by lasers in near-critical-density plasmas

    PubMed Central

    Zhu, Xing-Long; Yu, Tong-Pu; Sheng, Zheng-Ming; Yin, Yan; Turcu, Ion Cristian Edmond; Pukhov, Alexander

    2016-01-01

    Pair production can be triggered by high-intensity lasers via the Breit–Wheeler process. However, the straightforward laser–laser colliding for copious numbers of pair creation requires light intensities several orders of magnitude higher than possible with the ongoing laser facilities. Despite the numerous proposed approaches, creating high-energy-density pair plasmas in laboratories is still challenging. Here we present an all-optical scheme for overdense pair production by two counter-propagating lasers irradiating near-critical-density plasmas at only ∼1022 W cm−2. In this scheme, bright γ-rays are generated by radiation-trapped electrons oscillating in the laser fields. The dense γ-photons then collide with the focused counter-propagating lasers to initiate the multi-photon Breit–Wheeler process. Particle-in-cell simulations indicate that one may generate a high-yield (1.05 × 1011) overdense (4 × 1022 cm−3) GeV positron beam using 10 PW scale lasers. Such a bright pair source has many practical applications and could be basis for future compact high-luminosity electron–positron colliders. PMID:27966530

  7. Study of dense helium plasma in the optimal hypernetted chain approximation

    SciTech Connect

    Mueller, H.; Langanke, K. )

    1994-01-01

    We have studied the helium plasma in the hypernetted chain approximation considering both short-ranged internuclear and long-ranged Coulomb interactions. The optimal two-particle wave function has been determined in fourth order; fifth-order corrections have been considered in the calculation of the two-body and three-body correlation functions. The latter has been used to determine the pycnonuclear triple-alpha-fusion rate in the density regime 10[sup 8] g/cm[sup 3][le][rho][le]10[sup 10] g/cm[sup 3], which is of importance for the crust evolution of an accreting old neutron star. The influence of three-particle terms in the many-body wave function on the rate is estimated within an additional variational hypernetted chain calculation. Our results support the idea that the helium liquid undergoes a phase transition to stable [sup 8]Be matter at densities [rho][approx]3[times]10[sup 9] g/cm[sup 3] as the plasma induced screening potential then becomes strong enough to bind the [sup 8]Be ground state.

  8. Nonlinear propagation of coherent electromagnetic waves in a dense magnetized plasma

    SciTech Connect

    Shukla, P. K.; Eliasson, B.; Stenflo, L.

    2012-07-15

    We present an investigation of the nonlinear propagation of high-frequency coherent electromagnetic waves in a uniform quantum magnetoplasma. Specifically, we consider nonlinear couplings of right-hand circularly polarized electromagnetic-electron-cyclotron (CPEM-EC) waves with dispersive shear Alfven (DSA) and dispersive compressional Alfven (DCA) perturbations in plasmas composed of degenerate electron fluids and non-degenerate ion fluids. Such interactions lead to amplitude modulation of the CPEM-EC wave packets, the dynamics of which is governed by a three-dimensional nonlinear Schroedinger equation (NLSE) with the frequency shift arising from the relativistic electron mass increase in the CPEM-EC fields and density perturbations associated with the DSA and DCA perturbations. Accounting for the electromagnetic and quantum forces, we derive the evolution equation for the DSA and DCA waves in the presence of the magnetic field-aligned ponderomotive force of the CPEM-EC waves. The NLSE and the driven DSA and DCA equations are then used to investigate the modulational instability. The relevance of our investigation to laser-plasma interaction experiments and the cores of white dwarf stars is pointed out.

  9. Frontiers of the Physics of Dense Plasmas and Planetary Interiors: Experiment, Theory, Applications

    SciTech Connect

    Fortney, J J; Glenzer, S H; Koenig, M; Brambrink, E; Militzer, B; Saumon, D; Valencia, D

    2008-09-12

    We review recent developments of dynamic x-ray characterization experiments of dense matter, with particular emphasis on conditions relevant to interiors of terrestrial and gas giant planets. These studies include characterization of compressed states of matter in light elements by x-ray scattering and imaging of shocked iron by radiography. We examine several applications of this work. These include the structure of massive 'Super Earth' terrestrial planets around other stars, the 40 known extrasolar gas giants with measured masses and radii, and Jupiter itself, which serves as our benchmark for giant planets. We are now in an era of dramatic improvement in our knowledge of the physics of materials at high density. For light elements, this theoretical and experimental work has many applications, including internal confinement fusion as well as the interiors of gas giant planets. For heavy elements, experiments on silicates and iron at high pressure are helping to better understand the Earth, as well as terrestrial planets as a class of objects. In particular, the discovery of rocky and gaseous planets in other planetary systems has opened our imaginations to planets not found in our own solar system. While the fields of experiments of matter at high densities, first principles calculations of equations of state (EOS), planetary science, and astronomy do progress independently of each other, it is important for there to be communication between fields. For instance, in the realm of planets, physicists can learn of key problems that exist in the area of planetary structure, and how advances in our understanding of input physics could shed new light in this area. Astronomers and planetary scientists can learn where breakthroughs in physics of materials under extreme conditions are occurring, and be ready to apply these findings within their fields.

  10. Spectroscopic ellipsometry on Si/SiO{sub 2}/graphene tri-layer system exposed to downstream hydrogen plasma: Effects of hydrogenation and chemical sputtering

    SciTech Connect

    Eren, Baran; Fu, Wangyang; Marot, Laurent Calame, Michel; Steiner, Roland; Meyer, Ernst

    2015-01-05

    In this work, the optical response of graphene to hydrogen plasma treatment is investigated with spectroscopic ellipsometry measurements. Although the electronic transport properties and Raman spectrum of graphene change after plasma hydrogenation, ellipsometric parameters of the Si/SiO2/graphene tri-layer system do not change. This is attributed to plasma hydrogenated graphene still being electrically conductive, since the light absorption of conducting 2D materials does not depend on the electronic band structure. A change in the light transmission can only be observed when higher energy hydrogen ions (30 eV) are employed, which chemically sputter the graphene layer. An optical contrast is still apparent after sputtering due to the remaining traces of graphene and hydrocarbons on the surface. In brief, plasma treatment does not change the light transmission of graphene; and when it does, this is actually due to plasma damage rather than plasma hydrogenation.

  11. First-principles thermal conductivity of warm-dense deuterium plasmas for inertial confinement fusion applications

    NASA Astrophysics Data System (ADS)

    Hu, S. X.; Collins, L. A.; Boehly, T. R.; Kress, J. D.; Goncharov, V. N.; Skupsky, S.

    2014-04-01

    Thermal conductivity (κ) of both the ablator materials and deuterium-tritium (DT) fuel plays an important role in understanding and designing inertial confinement fusion (ICF) implosions. The extensively used Spitzer model for thermal conduction in ideal plasmas breaks down for high-density, low-temperature shells that are compressed by shocks and spherical convergence in imploding targets. A variety of thermal-conductivity models have been proposed for ICF hydrodynamic simulations of such coupled and degenerate plasmas. The accuracy of these κ models for DT plasmas has recently been tested against first-principles calculations using the quantum molecular-dynamics (QMD) method; although mainly for high densities (ρ > 100 g/cm3), large discrepancies in κ have been identified for the peak-compression conditions in ICF. To cover the wide range of density-temperature conditions undergone by ICF imploding fuel shells, we have performed QMD calculations of κ for a variety of deuterium densities of ρ = 1.0 to 673.518 g/cm3, at temperatures varying from T = 5 × 103 K to T = 8 × 106 K. The resulting κQMD of deuterium is fitted with a polynomial function of the coupling and degeneracy parameters Γ and θ, which can then be used in hydrodynamic simulation codes. Compared with the "hybrid" Spitzer-Lee-More model currently adopted in our hydrocode lilac, the hydrosimulations using the fitted κQMD have shown up to ˜20% variations in predicting target performance for different ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility (NIF). The lower the adiabat of an imploding shell, the more variations in predicting target performance using κQMD. Moreover, the use of κQMD also modifies the shock conditions and the density-temperature profiles of the imploding shell at early implosion stage, which predominantly affects the final target performance. This is in contrast to the previous speculation that κQMD changes mainly the

  12. First-principles thermal conductivity of warm-dense deuterium plasmas for inertial confinement fusion applications.

    PubMed

    Hu, S X; Collins, L A; Boehly, T R; Kress, J D; Goncharov, V N; Skupsky, S

    2014-04-01

    Thermal conductivity (κ) of both the ablator materials and deuterium-tritium (DT) fuel plays an important role in understanding and designing inertial confinement fusion (ICF) implosions. The extensively used Spitzer model for thermal conduction in ideal plasmas breaks down for high-density, low-temperature shells that are compressed by shocks and spherical convergence in imploding targets. A variety of thermal-conductivity models have been proposed for ICF hydrodynamic simulations of such coupled and degenerate plasmas. The accuracy of these κ models for DT plasmas has recently been tested against first-principles calculations using the quantum molecular-dynamics (QMD) method; although mainly for high densities (ρ > 100 g/cm3), large discrepancies in κ have been identified for the peak-compression conditions in ICF. To cover the wide range of density-temperature conditions undergone by ICF imploding fuel shells, we have performed QMD calculations of κ for a variety of deuterium densities of ρ = 1.0 to 673.518 g/cm3, at temperatures varying from T = 5 × 103 K to T = 8 × 106 K. The resulting κQMD of deuterium is fitted with a polynomial function of the coupling and degeneracy parameters Γ and θ, which can then be used in hydrodynamic simulation codes. Compared with the "hybrid" Spitzer-Lee-More model currently adopted in our hydrocode lilac, the hydrosimulations using the fitted κQMD have shown up to ∼20% variations in predicting target performance for different ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility (NIF). The lower the adiabat of an imploding shell, the more variations in predicting target performance using κQMD. Moreover, the use of κQMD also modifies the shock conditions and the density-temperature profiles of the imploding shell at early implosion stage, which predominantly affects the final target performance. This is in contrast to the previous speculation that κQMD changes mainly the

  13. Effects of weakly coupled and dense quantum plasmas environments on charge exchange and ionization processes in Na+ + Rb(5s) atom collisions

    NASA Astrophysics Data System (ADS)

    Pandey, Mukesh Kumar; Lin, Yen-Chang; Ho, Yew Kam

    2017-02-01

    The effects of weakly coupled or classical and dense quantum plasmas environment on charge exchange and ionization processes in Na+ + Rb(5s) atom collision at keV energy range have been investigated using classical trajectory Monte Carlo (CTMC) method. The interaction of three charged particles are described by the Debye-Hückel screen potential for weakly coupled plasma, whereas exponential cosine-screened Coulomb potential have been used for dense quantum plasma environment and the effects of both conditions on the cross sections are compared. It is found that screening effects on cross sections in high Debye length condition is quite small in both plasma environments. However, enhanced screening effects on cross sections are observed in dense quantum plasmas for low Debye length condition, which becomes more effective while decreasing the Debye length. Also, we have found that our calculated results for plasma-free case are comparable with the available theoretical results. These results are analyzed in light of available theoretical data with the choice of model potentials.

  14. Replacement of hydrogen peroxide cleaning with oxygen plasma

    NASA Astrophysics Data System (ADS)

    Adams, B. E.

    1992-03-01

    Comparison between the standard peroxide cleaning method and an oxygen plasma modified version was run on thin film bond monitors. The plasma modified version substituted oxygen plasma for the peroxide cleaning step in the process and reduced the DI rinse water temperature from 75 C to 25 C. A direct surface cleanliness comparison was made between the two cleaning methods using Auger spectroscopy. A beam lead and ribbon bonding experiment was also run on plasma-cleaned networks. Results of both experiments indicate that plasma cleaning is superior to peroxide cleaning and that reliable bonding can be done on plasma-cleaned thin film networks.

  15. Hydrogen pumping and release by graphite under high flux plasma bombardment

    SciTech Connect

    Hirooka, Y.; Leung, W.K.; Conn, R.W.; Goebel, D.M.; LaBombard, B.; Nygren, R.; Wilson, K.L.

    1988-01-01

    Inert gas (helium or argon) plasma bombardment has been found to increase the surface gas adsorptivity of isotropic graphite (POCO-graphite), which can then getter residual gases in a high vacuum system. The inert gas plasma bombardment was carried out at a flux approx. = 1 x 10/sup 18/ ions s/sup -1/ cm/sup -2/ to a fluence of the order of 10/sup 21/ ions/cm/sup 2/ and at temperatures around 800/sup 0/C. The gettering capability of graphite can be easily recovered by repeating inert gas plasma bombardment. The activated graphite surface exhibits a smooth, sponge-like morphology with significantly increased pore openings, which correlates with the observed increase in the surface gas adsorptivity. The activated graphite surface has been observed to pump hydrogen plasma particles as well. From calibrated H-alpha measurements, the dynamic hydrogen retention capacity is evaluated to be as large as 2 x 10/sup 18/ H/cm/sup 2/ at temperatures below 100/sup 0/C and at a plasma bombarding energy of 300 eV. The graphite temperature was varied between 15 and 480/sup 0/C. Due to the plasma particle pumping capability, hydrogen recycling from the activated graphite surface is significantly reduced, relative to that from a pre-saturated surface. A pre-saturated surface was also observed to reproducibly pump a hydrogen plasma to a concentration of 9.5 x 10/sup 17/ H/cm/sup 2/. The hydrogen retention capacity of graphite is found to decrease with increasing temperature. A transient pumping mechanism associated with the sponge-like surface morphology is conjectured to explain the large hydrogen retention capacity. Hydrogen release behavior under helium and argon plasma bombardment was also investigated, and the result indicated the possibility of some in-pore retrapping effect. 43 refs., 11 figs.

  16. Modeling of dense injection-seeded Ni-like Krypton plasma amplifiers

    NASA Astrophysics Data System (ADS)

    Oliva, Eduardo; Depresseux, Adrien; Tissandier, Fabien; Gautier, Julien; Sebban, Stéphane; Maynard, Gilles

    2015-09-01

    One promising way to reach ultra-short soft X-ray lasers is to guide an intense infrared pulse through a plasma channel generated in a high pressure gas. However, in such a case, strong non-linear effects, as overionizationinduced refraction and self-focusing, hinder the propagation of the laser beam and thus the creation of the lasing ion and the population inversion. Using a particle-in-cell (PIC) code and a ray-tracing model, we demonstrate that a stable self-regulation mechanism between self-focusing and overionization appears, which enables guiding the infrared beam over several milimetres, well beyond the saturation length for amplification of the soft X-ray laser.

  17. Isotopic effect of parametric instabilities during lower hybrid waves injection into hydrogen/deuterium plasmas

    NASA Astrophysics Data System (ADS)

    Zhao, Aihui; Gao, Zhe

    2017-01-01

    Based on the local dispersion relation, the parametric instability (PI) was numerically investigated for the injection of lower hybrid waves (LHWs) into hydrogen and deuterium plasmas separately. Numerical calculations under typical scrape-off layer parameters in tokamak plasmas show that both the unstable regions of the PI and the values of growth rates are close for two cases, in spite of the decaying channel of the ion sound quasimode or ion cyclotron quasimode (ICQM). These numerical results could be understood by the analyses based on the fluid model. Parameter dependences are also similar for hydrogen and deuterium plasmas. For example, the ICQM growth rate increases with an increasing density, a decreasing temperature, and a decreasing magnetic field in deuterium plasmas as it does in hydrogen plasmas. The isotopic effect of the PI during the LHW injection is weak. As a result, the lower hybrid current drive efficiency at a high density in deuterium plasmas cannot be much improved over hydrogen plasmas if the PI process dominates the behavior of LHWs at the plasma edge.

  18. A fresh look at dense hydrogen under pressure. II. Chemical and physical models aiding our understanding of evolving H-H separations.

    PubMed

    Labet, Vanessa; Hoffmann, Roald; Ashcroft, N W

    2012-02-21

    In order to explain the intricate dance of intramolecular (intra-proton-pair) H-H separations observed in a numerical laboratory of calculationally preferred static hydrogen structures under pressure, we examine two effects through discrete molecular models. The first effect, we call it physical, is of simple confinement. We review a salient model already in the literature, that of LeSar and Herschbach, of a hydrogen molecule in a spheroidal cavity. As a complement, we also study a hydrogen molecule confined along a line between two helium atoms. As the size of the cavity/confining distance decreases (a surrogate for increasing pressure), in both models the equilibrium proton separation decreases and the force constant of the stretching vibration increases. The second effect, which is an orbital or chemical factor, emerges from the electronic structure of the known molecular transition metal complexes of dihydrogen. In these the H-H bond is significantly elongated (and the vibron much decreased in frequency) as a result of depopulation of the σ(g) bonding molecular orbital of H(2), and population of the antibonding σ(u)∗ MO. The general phenomenon, long known in chemistry, is analyzed through a specific molecular model of three hydrogen molecules interacting in a ring, a motif found in some candidate structures for dense hydrogen.

  19. Detector and energy analyzer for energetic-hydrogen in beams and plasmas

    DOEpatents

    Bastasz, Robert J.; Hughes, Robert C.; Wampler, William R.

    1988-01-01

    A detector for detecting energetic hydrogen ions and atoms ranging in energy from about 1 eV up to 1 keV in an evacuated environment includes a Schottky diode with a palladium or palladium-alloy gate metal applied to a silicondioxide layer on an n-silicon substrate. An array of the energetic-hydrogen detectors having a range of energy sensitivities form a plasma energy analyzer having a rapid response time and a sensitivity for measuring fluxes of energetic hydrogen. The detector is sensitive to hydrogen and its isotopes but is insensitive to non-hydrogenic particles. The array of energetic-hydrogen detectors can be formed on a single silicon chip, with thin-film layers of gold metal applied in various thicknesses to successive detectors in the array. The gold layers serve as particle energy-filters so that each detector is sensitive to a different range of hydrogen energies.

  20. Detector and energy analyzer for energetic-hydrogen in beams and plasmas

    DOEpatents

    Bastasz, R.J.; Hughes, R.C.; Wampler, W.R.

    1988-11-01

    A detector for detecting energetic hydrogen ions and atoms ranging in energy from about 1 eV up to 1 keV in an evacuated environment includes a Schottky diode with a palladium or palladium-alloy gate metal applied to a silicon-dioxide layer on an n-silicon substrate. An array of the energetic-hydrogen detectors having a range of energy sensitivities form a plasma energy analyzer having a rapid response time and a sensitivity for measuring fluxes of energetic hydrogen. The detector is sensitive to hydrogen and its isotopes but is insensitive to non-hydrogenic particles. The array of energetic-hydrogen detectors can be formed on a single silicon chip, with thin-film layers of gold metal applied in various thicknesses to successive detectors in the array. The gold layers serve as particle energy-filters so that each detector is sensitive to a different range of hydrogen energies. 4 figs.

  1. Hydrogen Storage in Diamond Powder Utilizing Plasma NaF Surface Treatment for Fuel Cell Applications

    SciTech Connect

    Leal, David A.; Leal-Quiros, E.; Velez, Angel; Prelas, Mark A.; Gosh, Tushar

    2006-12-04

    Hydrogen Fuel Cells offer the vital solution to the world's socio-political dependence on oil. Due to existing difficulty in safe and efficient hydrogen storage for fuel cells, storing the hydrogen in hydrocarbon compounds such as artificial diamond is a realistic solution. By treating the surface of the diamond powder with a Sodium Fluoride plasma exposure, the surface of the diamond is cleaned of unwanted molecules. Due to fluorine's electro negativity, the diamond powder is activated and ready for hydrogen absorption. These diamond powder pellets are then placed on a graphite platform that is heated by conduction in a high voltage circuit made of tungsten wire. Then, the injection of hydrogen gas into chamber allows the storage of the Hydrogen on the surface of the diamond powder. By neutron bombardment in the nuclear reactor, or Prompt Gamma Neutron Activation Analysis, the samples are examined for parts per million amounts of hydrogen in the sample. Sodium Fluoride surface treatment allows for higher mass percentage of stored hydrogen in a reliable, resistant structure, such as diamond for fuel cells and permanently alters the diamonds terminal bonds for re-use in the effective storage of hydrogen. The highest stored amount utilizing the NaF plasma surface treatment was 22229 parts per million of hydrogen in the diamond powder which amounts to 2.2229% mass increase.

  2. Energy density dependence of hydrogen combustion efficiency in atmospheric pressure microwave plasma

    SciTech Connect

    Yoshida, T.; Ezumi, N.; Sawada, K.; Tanaka, Y.; Tanaka, M.; Nishimura, K.

    2015-03-15

    The recovery of tritium in nuclear fusion plants is a key issue for safety. So far, the oxidation procedure using an atmospheric pressure plasma is expected to be part of the recovery method. In this study, in order to clarify the mechanism of hydrogen oxidation by plasma chemistry, we have investigated the dependence of hydrogen combustion efficiency on gas flow rate and input power in the atmospheric pressure microwave plasma. It has been found that the combustion efficiency depends on energy density of absorbed microwave power. Hence, the energy density is considered as a key parameter for combustion processes. Also neutral gas temperatures inside and outside the plasma were measured by an optical emission spectroscopy method and thermocouple. The result shows that the neutral gas temperature in the plasma is much higher than the outside temperature of plasma. The high neutral gas temperature may affect the combustion reaction. (authors)

  3. Heating of a Magnetized High Density Hydrogen Plasma Column Around the ICR Frequency

    NASA Astrophysics Data System (ADS)

    Graswinckel, M. F.; Guadamuz, S.; Koch, R.; Maggiora, R.; Van De Pol, M.; Vietti, G.; Van Rooij, G.

    2011-12-01

    A single and double loop antenna system are investigated in the ICR frequency range (5-25 MHz) to enable control of the plasma temperature in a 1-10 cm diameter, 1020 m-3 hydrogen plasma column in B = 0.8T Wave propagation is evaluated on basis of damping lengths derived from the dispersion relation. The antenna is numerically analyzed with the TOPCYL code. Simulation results are compared with measured loading resistances and good agreement was found for the vacuum and saltwater column cases. Hydrogen plasma loading resistances determined from network analyzer measurements are typically higher than those predicted from simulation. This points to coupling of RF power to additional loss mechanisms. High RF power operation (1 kW) of the antenna increased the power deposited on the plasma endplate and accelerated the plasma, but the plasma temperature near the endplate remained constant.

  4. The contribution of dissociative processes to the production of atomic lines in hydrogen plasmas

    NASA Technical Reports Server (NTRS)

    Kunc, J. A.

    1985-01-01

    The contribution of molecular dissociative processes to the production of atomic lines is considered for a steady-state hydrogen plasma. If the contribution of dissociative processes is dominant, a substantial simplification in plasma diagnostics can be achieved. Numerical calculations have been performed for the production of Balmer alpha, beta, and gamma lines in hydrogen plasmas with medium and large degrees of ionization (x greater than about 0.0001) and for electron temperatures of 5000-45,000 K and electron densities of 10 to the 10th to 10 to the 16th/cu cm.

  5. The Diagnostics Of Hydrogen-Cesium Plasma Using Fully Relativistic Electron Impact Cross Sections

    NASA Astrophysics Data System (ADS)

    Priti, Priti; Dipti, Dipti; Gangwar, Reetesh; Srivastava, Rajesh

    2016-10-01

    Electron excitation cross-sections and rate coefficients have been calculated using fully relativistic distorted wave theory for several fine-structure transitions from the ground as well as excited states of cesium atom in the wide range of incident electron energy. These processes play dominant role in low pressure hydrogen-cesium plasma relevant to the negative ion based neutral beam injectors for the ITER project. The calculated cross-sections are used to construct a reliable collisional radiative (CR) model to characterize the hydrogen-cesium plasma. The calculated plasma parameters are compared with the available experimental and theoretical results.

  6. Investigation of bonded hydrogen defects in nanocrystalline diamond films grown with nitrogen/methane/hydrogen plasma at high power conditions

    NASA Astrophysics Data System (ADS)

    Tang, C. J.; Hou, Haihong; Fernandes, A. J. S.; Jiang, X. F.; Pinto, J. L.; Ye, H.

    2017-02-01

    In this work, we investigate the influence of some growth parameters such as high microwave power ranging from 3.0 to 4.0 kW and N2 additive on the incorporation of bonded hydrogen defects in nanocrystalline diamond (NCD) films grown through a small amount of pure N2 addition into conventional 4% CH4/H2 plasma using a 5 kW microwave plasma CVD system. Incorporation form and content of hydrogen point defects in the NCD films produced with pure N2 addition was analyzed by employing Fourier-transform infrared (FTIR) spectroscopy for the first time. A large amount of hydrogen related defects was detected in all the produced NCD films with N2 additive ranging from 29 to 87 μm thick with grain size from 47 nm to 31 nm. Furthermore, a specific new H related sharp absorption peak appears in all the NCD films grown with pure N2/CH4/H2 plasma at high powers and becomes stronger at powers higher than 3.0 kW and is even stronger than the 2920 cm-1 peak, which is commonly found in CVD diamond films. Based on these experimental findings, the role of high power and pure nitrogen addition on the growth of NCD films including hydrogen defect formation is analyzed and discussed.

  7. Equation of state of a dense plasma: Analytical results on the basis of quantum pair interaction potentials in the random phase approximation

    NASA Astrophysics Data System (ADS)

    Moldabekov, Zh A.; Ramazanov, T. S.; Gabdullin, M. T.

    2016-11-01

    In this work, using recently obtained expansion of the dielectric function in the long wave length limit by Moldabekov et al (2015 Phys. Plasmas 22 102104), we extended previously obtained formulas for the equation of state of the semiclassical dense plasma from Ramazanov et al (2015 Phys. Rev. E 92 023104) to the quantum case. Inner energy and contribution to the pressure due to plasma non-ideality derived for both Coulomb pair interaction and quantum pair interaction potentials. Obtained analytical result for the equation of state reproduces the Montroll-Ward contribution, which corresponds to the quantum ring sum. It was shown that the obtained results are consistent with the Thomas-Fermi approximation with the first order gradient correction. Additionally, the generalization of the quantum Deutsch potential to the case of the degenerate electrons is discussed. Obtained results will be useful for understanding of the physics of dense plasmas as well as for further development of the dense plasma simulation on the basis of the quantum potentials.

  8. Copper dry etching by sub-atmospheric-pressure pure hydrogen glow plasma

    NASA Astrophysics Data System (ADS)

    Ohmi, Hiromasa; Sato, Jumpei; Hirano, Tatsuya; Kubota, Yusuke; Kakiuchi, Hiroaki; Yasutake, Kiyoshi

    2016-11-01

    Copper (Cu) dry etching is demonstrated using a narrow-gap hydrogen plasma generated at 13.3 kPa (100 Torr) for applications in the Cu wiring technology of integrated circuits. A localized hydrogen plasma is generated around the apex of a fine pipe electrode. The Cu etching can be observed only when the process gas contains hydrogen, and the etching rates decrease with decreased hydrogen concentration. The plasma heating effect owing to plasma localization is negligible for the Cu etching because no etching occurs in the presence of pure N2 plasma whose volume is almost equal to that of the pure H2 plasma. Furthermore, the influences of physical sputtering and vacuum ultraviolet irradiation on the Cu etching are confirmed to be insignificant by exposing the samples to rare-gas plasma. The maximum Cu etching rate of 500 nm/min can be achieved at a stage temperature of 0 °C. However, the Cu etching rate has no obvious dependence on the stage temperature in a range from -20 to 330 °C. In contrast, the etching rates for Si and SiO2 at a stage temperature of 0 °C are 100 μm/min and 50 nm/min, respectively. The Cu etching rate is 10 times higher than that of SiO2, which implies that this etching technique has potential applications for Cu wiring on an SiO2 layer. The Cu surface etched by the hydrogen plasma is roughened and exhibits many round pits and bumps, which seems to be owing to excessive incorporation of the diffused hydrogen in the Cu bulk.

  9. Physical processes taking place in dense plasma focus devices at the interaction of hot plasma and fast ion streams with materials under test

    NASA Astrophysics Data System (ADS)

    Gribkov, V. A.

    2015-06-01

    The dense plasma focus (DPF) device represents a source of powerful streams of penetrating radiations (hot plasma, fast electron and ion beams, x-rays and neutrons) of ns-scale pulse durations. Power flux densities of the radiation types may reach in certain cases the values up to 1013 W cm  -  2. They are widely used at present time in more than 30 labs in the world in the field of radiation material science. Areas of their implementations are testing of the materials perspective for use in modern fusion reactors (FR) of both types, modification of surface layers with an aim of improvements their properties, production of some nanostructures on their surface, and so on. To use a DPF correctly in these applications it is important to understand the mechanisms of generation of the above-mentioned radiations, their dynamics inside and outside of the pinch and processes of interaction of these streams with targets. In this paper, the most important issues on the above matter we discuss in relation to the cumulative hot plasma stream and the beam of fast ions with illustration of experimental results obtained at four DPF devices ranged in the limits of bank energies from 1 kJ to 1 MJ. Among them mechanisms of a jet formation, a current abruption phenomenon, a super-Alfven ion beam propagation inside and outside of DPF plasma, generation of secondary plasma and formation of shock waves in plasma and inside a solid-state target, etc. Nanosecond time-resolved techniques (electric probes, laser interferometry, frame self-luminescent imaging, x-ray/neutron probes, etc) give an opportunity to investigate the above-mentioned events and to observe the process of interaction of the radiation types with targets. After irradiation, we analyzed the specimens by contemporary instrumentation: optical and scanning electron microscopy, local x-ray spectral and structure analysis, atomic force microscopy, the portable x-ray diffractometer that combines x-ray single

  10. Broadening and shift of the spectral lines of hydrogen atoms and silicon ions in laser plasma

    SciTech Connect

    Kask, N E; Leksina, E G; Michurin, S V; Fedorov, G M; Chopornyak, D B

    2015-06-30

    We report an experimental investigation of the broadening and shift of discrete lines in the plasma spectrum produced in the laser ablation of silicon in a broad pressure range (10{sup 2} – 10{sup 7} Pa) of the ambient gas (Ar, He, H{sub 2}). The broadening and line shifts are measured in relation to the distance from the target and initial gas pressure. The threshold nature of the resulting dependences is found to be related to the formation of virtual percolation clusters proceeding in the hot dense plasma. (laser plasma)

  11. Refinement of the semiclassical theory of the Stark broadening of hydrogen spectral lines in plasmas

    NASA Astrophysics Data System (ADS)

    Oks, Eugene

    2015-02-01

    Stark broadening (SB) of hydrogen, deuterium, and tritium lines (H-lines) is an important diagnostic tool for many applications. The most "user-friendly" are semiclassical theories of the SB of H-lines: their results can be expressed analytically in a relatively simple form for any H-line. The simplest semiclassical theory is the so-called Conventional Theory (CT), which is frequently referred to as Griem's theory. While by now there are several significantly more advanced semiclassical "non-CT" theories of the SB, Griem's CT is still used by a number of groups performing laboratory experiments or astrophysical observations for the comparison with their experimental or observational results. In the present study we engage unexplored capabilities of the CT for creating analytically a more accurate CT. First, we take into account that the perturbing electrons actually do not move as free particles: rather they move in a dipole potential V=·r/r3, where r is the radius-vector of the perturbing electrons and is the mean value of the radius vector of the atomic electron. Second, Griem's definition of the so-called Weisskopf radius was not quite accurate. Third, in his book of year 1974, Griem suggested changing so-called strong collision constant without changing the Weisskopf radius, while in reality the choices of the Weisskopf radius and of the strong collision constant are interrelated. We show that the above refinements of the CT increase the electron broadening - especially for warm dense plasmas emitting H-lines. By comparison with benchmark experiments concerning the Hα line we demonstrate that the effect of the ion dynamics (neglected in any CT) might be slightly smaller than previously thought, while the effect of the acceleration of perturbing electrons by the ion field in the vicinity of the radiating atom (neglected in any CT) might be greater than previously thought.

  12. Local optical emission spectroscopy of excited species effused from an evaporation cell and a sputter source into dense plasmas - Basic studies for the deposition of thin gradient films.

    PubMed

    Bolt, H; Hemel, V; Koch, F; Nickel, H

    1996-06-01

    Space resolved optical emission spectroscopy has been applied to determine the distribution of excited species in dense plasmas which are used for the deposition of thin coatings. Typical electron densities and electron temperatures in the plasma facility PETRA ( Plasma Engineering and Technology Research Assembly) are in the range of n(e) = 10(12) cm(-3) and T(e) = 10 eV. During the deposition process material (Al) is evaporated from a vapour cell under controlled conditions. The vapour stream is guided into a dense plasma which is composed of inert gas, Ar or He, and hydrocarbon species produced from the dissociation of C(2)H(2). The evaporated Al-stream which travels with thermal velocity into a plasma of high electron density, is nearly completely ionized due to the short mean free path for electron impact ionization in the above mentioned parameter range. Optical emission spectroscopy has been applied to investigate the interaction processes between the vapour stream and the plasma as well as the transport of the ionized Al along the applied magnetic field. For the measurements space resolved optical emission spectroscopy with an in-situ translation mechanism of the optical fibre has been used to measure the local concentrations of excited Al neutrals and ions as well as the concentration of the background plasma species.

  13. Simulation of the Correlated Electron Plasma in the Warm Dense Matter Regime by Restricted Path-Integral Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Kapila, Vivek; Deymier, Pierre; Runge, Keith

    2012-02-01

    Warm dense matter (WDM) can be characterized by electron temperatures of a few eV and densities an order of magnitude or more beyond ambient. This regime currently lacks any adequate highly developed class of simulation methods. Recent developments in orbital-free Density Functional Theory (ofDFT) aim to provide such a simulation method, however, little benchmark information is available on temperature and pressure dependence of simple but realistic models in WDM regime. The present work aims to fill this critical gap using the restricted path-integral molecular dynamics (rPIMD) method. Within the discrete path integral representation, electrons are described as harmonic necklaces, while, quantum exchange takes the form of cross linking between electron necklaces. The fermion sign problem is addressed by restricting the density matrix to positive values and a molecular dynamics algorithm is employed to sample phase space. Here, we focus on the behavior of strongly correlated electron plasmas under WDM conditions. We compute the kinetic and potential energies and compare them to those obtained with the ofDFT method.

  14. Nuclear particle decay in a multi-MeV beam ejected by pulsed-laser impact on ultra-dense hydrogen H(0)

    NASA Astrophysics Data System (ADS)

    Holmlid, Leif

    2015-10-01

    The multi-MeV particles ejected from pulsed laser-induced processes in ultra-dense hydrogen H(0) are observed in vacuum at three different distances up to 2m from the laser target. In previous publications, massive neutral particles with energy of 1-30MeVu-1 were identified. Direct energy spectra of the particles show energies well above 1MeV. The particles studied here interact with metallic collectors and give signals due to several processes like secondary electron emission and lepton pair production (published). Two experimental facts are immediate: (1) the signal per sr at large distance is up to 10 times higher than at short distance, (2) the signal at large distance is faster in real time than at short distance. These results show directly that the signal at long distance is mainly due to a mixture of intermediate particles formed by decay in the beam. The decaying signals have time constants of approximately 12 and 26ns for ultra-dense deuterium D(0) and 52 ns for ultra-dense protium p(0). These decay time constants agree well with those for decay of light mesons. These particles with narrow MeV energy distributions are formed by stepwise decay from particles like HN(0). The main result is that a decaying particle flux is formed by the laser-induced processes. The final muons produced may be useful for muon catalyzed fusion.

  15. [Study on the Emission Spectrum of Hydrogen Production with Microwave Discharge Plasma in Ethanol Solution].

    PubMed

    Sun, Bing; Wang, Bo; Zhu, Xiao-mei; Yan, Zhi-yu; Liu, Yong-jun; Liu, Hui

    2016-03-01

    Hydrogen is regarded as a kind of clean energy with high caloricity and non-pollution, which has been studied by many experts and scholars home and abroad. Microwave discharge plasma shows light future in the area of hydrogen production from ethanol solution, providing a new way to produce hydrogen. In order to further improve the technology and analyze the mechanism of hydrogen production with microwave discharge in liquid, emission spectrum of hydrogen production by microwave discharge plasma in ethanol solution was being studied. In this paper, plasma was generated on the top of electrode by 2.45 GHz microwave, and the spectral characteristics of hydrogen production from ethanol by microwave discharge in liquid were being studied using emission spectrometer. The results showed that a large number of H, O, OH, CH, C2 and other active particles could be produced in the process of hydrogen production from ethanol by microwave discharge in liquid. The emission spectrum intensity of OH, H, O radicals generated from ethanol is far more than that generated from pure water. Bond of O-H split by more high-energy particles from water molecule was more difficult than that from ethanol molecule, so in the process of hydrogen production by microwave discharge plasma in ethanol solution; the main source of hydrogen was the dehydrogenation and restructuring of ethanol molecules instead of water decomposition. Under the definite external pressure and temperature, the emission spectrum intensity of OH, H, O radicals increased with the increase of microwave power markedly, but the emission spectrum intensity of CH, C2 active particles had the tendency to decrease with the increase of microwave power. It indicated that the number of high energy electrons and active particles high energy electron energy increased as the increase of microwave power, so more CH, C2 active particles were split more thoroughly.

  16. Bactericidal effect of plasma jet with helium flowing through 3% hydrogen peroxide against Enterococcus faecalis.

    PubMed

    Zhou, Xin-Cai; Li, Yu-Lan; Liu, De-Xi; Cao, Ying-Guang; Lu, Xin-Pei

    2016-11-01

    The aim of the present study was to assess the antimicrobial activity of plasma jet with helium (He) flowing through 3% hydrogen peroxide in root canals infected with Enterococcus faecalis. A total of 42 single-rooted anterior teeth were prepared, sterilized, inoculated with an E. faecalis suspension and incubated for 7 days. Next, the teeth were randomly divided into six experimental groups (including groups treated by plasma jet with or without He for different time durations) and one control group treated without plasma. The number of surviving bacteria in each canal was determined by counting the colony forming units (CFU)/ml on nutrient agar plates. The results indicated that statistically significant reduction in CFU/ml (P<0.005) existed for all treatment groups relative to the control group. The greatest reductions in CFU/ml were observed for Group 3 (7.027 log unit reduction) and Group 2 (6.237 log unit reduction), which were treated by plasma jet sterilization with He flowing through 3% hydrogen peroxide for 4 min or for 2 min, respectively. In addition, the reduction in Group 3 was significantly greater compared with that in Group 2 or in the groups treated by plasma jet sterilization without He flowing through 3% hydrogen peroxide for 1, 2 or 4 min. In conclusion, plasma jet with or without He flowing through 3% hydrogen peroxide can effectively sterilized root canals infected with E. faecalis and should be considered as an alternative method for root canal disinfection in endodontic treatments.

  17. Plasma Transport in a Magnetic Multicusp Negative Hydrogen Ion Source

    DTIC Science & Technology

    1991-12-01

    the Extraction Electrode ............................ 4-4 Analysis of the Effect of Temperature Gradients on the Flux...Measured vs Predicted Ion Species Percentages ......... 5-31 x Abstract An analysis of plasma transport through the magnetic filter in mag- netic...diffusion through the magnetic filter field into the extraction chamber. The goal was not, however, simply to calculate the plasma potential. Analysis of

  18. Simulation of DBD plasma actuators, and nanoparticle-plasma interactions in argon-hydrogen CCP RF discharges

    NASA Astrophysics Data System (ADS)

    Mamunuru, Meenakshi

    The focus of this work is modeling and simulation of low temperature plasma discharges (LTPs). The first part of the thesis consists of the study of dielectric barrier (DBD) plasma actuators. Use of DBD plasma actuators on airfoil surfaces is a promising method for increasing airfoil efficiency. Actuators produce a surface discharge that causes time averaged thrust in the neutral gas. The thrust modifies the boundary layer properties of the flow and prevents the occurrence of separation bubbles. In simulating the working of an actuator, the focus is on the spatial characteristics of the thrust produced by the discharge over very short time and space scales. The results provide an understanding of the causes of thrust, and the basic principles behind the actuator operation. The second part of this work focusses on low pressure plasma discharges used for silicon nanoparticle synthesis. When reactive semiconductor precursor gases are passed through capacitively coupled plasma (CCP) radio frequency (RF) reactors, nano sized particles are formed. When the reactors are operated at high enough powers, a very high fraction of the nanoparticles are crystallized in the chamber. Nanoparticle crystallization in plasma is a very complex process and not yet fully understood. It can be inferred from experiments that bulk and surface processes initiated due to energetic ion impaction of the nanoparticles are responsible for reordering of silicon atoms, causing crystallization. Therefore, study of plasma-particle interactions is the first step towards understanding how particles are crystallized. The specific focus of this work is to investigate the experimental evidence that hydrogen gas presence in argon discharges used for silicon nanocrystal synthesis, leads to a superior quality of nanocrystals. Influence of hydrogen gas on plasma composition and discharge characteristics is studied. Via Monte Carlo simulation, distribution of ion energy impacting particles surface is studied

  19. Hydrogen manufacturing using plasma reformers. [Annual progress report], May 1, 1995--December 31, 1995

    SciTech Connect

    Cohn, D.R.; Bromberg, L.; Hochgreb, S.; O`Brien, C.; Rabinovich, A.

    1995-12-31

    Manufacturing of hydrogen from hydrocarbon fuels is needed for a variety of applications. These applications include fuel cells used in stationary electric power production and in vehicular propulsion. Hydrogen can also be used for various combustion engine systems. There is a wide range of requirements on the capacity of the hydrogen manufacturing system, the purity of the hydrogen fuel, and capability for rapid response. The overall objectives of a hydrogen manufacturing facility are to operate with high availability at the lowest possible cost and to have minimal adverse environmental impact. Plasma technology has potential to significantly alleviate shortcomings of conventional means of manufacturing hydrogen. These shortcomings include cost and deterioration of catalysts; limitations on hydrogen production from heavy hydrocarbons; limitations on rapid response; and size and weight requirements. In addition, use of plasma technology could provide for a greater variety of operating modes in particular the possibility of virtual elimination Of C0{sub 2} production by pyrolytic operation. This mode of hydrogen production may be of increasing importance due to recent additional evidence of global warming.

  20. Combined laser induced ignition and plasma spectroscopy: Fundamentals and application to a hydrogen air combustor

    NASA Astrophysics Data System (ADS)

    Zimmer, L.; Okai, K.; Kurosawa, Y.

    2007-12-01

    Combined Laser Induced Ignition and Plasma Spectroscopy (LI2PS) has the potential to give the exact local composition of a mixture at the ignition point and at the ignition time. However, as different laser energies are required to ignite a particular mixture as function of space, the typical approach using two power meters to calibrate the plasma spectroscopy measurement is not well suited. Furthermore, LI2PS requires single shot measurements and therefore high accuracy. In this paper, a novel calibration scheme is presented for application of Laser Induced Plasma Spectroscopy (LIPS) to gaseous analyses. Numerical simulations of air spectra are used to show that species emission can be used directly from the broadband spectra to determine the plasma conditions. The ratio of nitrogen emission around 744 nm and around 870 nm is found to be a sensitive indication of temperature in the emission ranging from 700 to 890 nm. Comparisons with experimental spectra show identical tendencies and validate the findings of the simulations. This approach is used in a partially-premixed hydrogen-air burner. First, helium is used instead of hydrogen. After an explanation of timing issue related to LIPS, it is shown that the calibration required depends only on nitrogen excitation and nitrogen-hydrogen ratio, without the need to know the deposited power. Measurements of the fuel distribution as function of injection momentum and spatial localization are reported. To illustrate the use of such a single shot approach, combined laser ignition and plasma spectroscopy is proposed. In this case, the calibration is based on hydrogen excitation and hydrogen-oxygen and hydrogen-nitrogen ratio. Results obtained with LI2PS show that ignition is successful only for high power and relatively high hydrogen concentration compared to the local mean. It is expected that LI2PS will become an important tool when dealing with partially-premixed or diffusion flame ignition.

  1. Optimization of the output and efficiency of a high power cascaded arc hydrogen plasma source

    SciTech Connect

    Vijvers, W. A. J.; Gils, C. A. J. van; Goedheer, W. J.; Meiden, H. J. van der; Veremiyenko, V. P.; Westerhout, J.; Lopes Cardozo, N. J.; Rooij, G. J. van; Schram, D. C.

    2008-09-15

    The operation of a cascaded arc hydrogen plasma source was experimentally investigated to provide an empirical basis for the scaling of this source to higher plasma fluxes and efficiencies. The flux and efficiency were determined as a function of the input power, discharge channel diameter, and hydrogen gas flow rate. Measurements of the pressure in the arc channel show that the flow is well described by Poiseuille flow and that the effective heavy particle temperature is approximately 0.8 eV. Interpretation of the measured I-V data in terms of a one-parameter model shows that the plasma production is proportional to the input power, to the square root of the hydrogen flow rate, and is independent of the channel diameter. The observed scaling shows that the dominant power loss mechanism inside the arc channel is one that scales with the effective volume of the plasma in the discharge channel. Measurements on the plasma output with Thomson scattering confirm the linear dependence of the plasma production on the input power. Extrapolation of these results shows that (without a magnetic field) an improvement in the plasma production by a factor of 10 over where it was in van Rooij et al. [Appl. Phys. Lett. 90, 121501 (2007)] should be possible.

  2. Numerical simulations based on probe measurements in EUV-induced hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Abrikosov, Alex; Reshetnyak, Viktor; Astakhov, Dmitry; Dolgov, Alexandr; Yakushev, Oleg; Lopaev, Dmitry; Krivtsun, Vladimir

    2017-04-01

    We use the two-dimensional particle-in-cell model with Monte Carlo collisions to study the plasma induced in hydrogen by short pulses of extreme ultraviolet (EUV) radiation at wavelengths in the range 10–20 nm with a pulse duration of about 40 ns (FWHM). This plasma is formed via both photoionization by the high-energy EUV photons and by the secondary photoelectrons emitted from the hydrogen molecules and the irradiated surface. The latter process can be enhanced by the external electric field that accelerates the electrons. In order to establish a base for our model so as to obtain accurate results, we record a temporally-resolved series of current–voltage characteristics for a small probing electrode inserted into EUV-induced hydrogen plasma. We then resort to simulating this plasma in the same geometry with the probe in our model which we validate by matching its results to the experimentally measured dynamics of the probe current–voltage curves. Having validated the model this way, we use this model as an independent instrument capable of obtaining the spatiotemporal picture of EUV-induced plasma evolution. We use this instrument to study the plasma formation during the EUV pulse and point out the processes that take part in forming this plasma, such as impact ionization and direct ionization by EUV photons.

  3. Stark broadening of hydrogen lines in magnetic fusion plasmas

    NASA Astrophysics Data System (ADS)

    Rosato, J.; Godbert-Mouret, L.; Koubiti, M.; Marandet, Y.; Stamm, R.

    2017-03-01

    We report on a Stark line shape model for the diagnostic of tokamak edge plasmas. In specific scenarios, plasma discharges are carried out at high density regimes, sufficiently so that the spectral lines emitted by the neutral atoms present in the edge and in the divertor region are affected by the plasma microscopic electric field (Stark broadening). We present new line shape calculations, carried out for diagnostic purposes in the context of the MST1 (Medium Sized Tokamak) European campaign. The role of the magnetic field (Zeeman effect) on line spectra is discussed.

  4. Reduction of a thin chromium oxide film on Inconel surface upon treatment with hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Vesel, Alenka; Mozetic, Miran; Balat-Pichelin, Marianne

    2016-11-01

    Inconel samples with a surface oxide film composed of solely chromium oxide with a thickness of approximately 700 nm were exposed to low-pressure hydrogen plasma at elevated temperatures to determine the suitable parameters for reduction of the oxide film. The hydrogen pressure during treatment was set to 60 Pa. Plasma was created by a surfaguide microwave discharge in a quartz glass tube to allow for a high dissociation fraction of hydrogen molecules. Auger electron depth profiling (AES) was used to determine the decay of the oxygen in the surface film and X-ray diffraction (XRD) to measure structural modifications. During hydrogen plasma treatment, the oxidized Inconel samples were heated to elevated temperatures. The reduction of the oxide film started at temperatures of approximately 1300 K (considering the emissivity of 0.85) and the oxide was reduced in about 10 s of treatment as revealed by AES. The XRD showed sharper substrate peaks after the reduction. Samples treated in hydrogen atmosphere under the same conditions have not been reduced up to approximately 1500 K indicating usefulness of plasma treatment.

  5. Microinstabilities in hydrogen- and helium-dominated multi-ion-species plasmas in LHD

    NASA Astrophysics Data System (ADS)

    Nunami, Masanori; Nakata, Motoki; Sugama, Hideo; Tanaka, Kenji; Toda, Shinichiro

    2017-04-01

    The ion scale microinstabilities in the large helical device (LHD) are investigated by the gyrokinetic simulations for the multi-ion-species plasmas including hydrogen, helium, and impurity ions. The observations in the LHD experiments show that the ion temperature increases with the decreases of the ratio of hydrogen density to helium density. It is found from the linear gyrokinetic simulations with the multi-ion-species and real-mass kinetic electrons in the LHD discharges that the growth rates of the ion scale microinstabilities are reduced for the helium-dominated multi-species plasma compared with the hydrogen-dominated one. In addition to the differences of the conditions including the temperature, the density profiles, and the temperature ratio between both plasmas, due to the dependence on the mass number and the electric charge of the mixed ion species, the mixing length estimates obtained from the linear simulations predicts smaller ion thermal diffusivity for the helium-dominated plasma than the hydrogen-dominated one in the hydrogen gyro-Bohm unit, which is consistent with the experimental results.

  6. Quantification of the VUV radiation in low pressure hydrogen and nitrogen plasmas

    NASA Astrophysics Data System (ADS)

    Fantz, U.; Briefi, S.; Rauner, D.; Wünderlich, D.

    2016-08-01

    Hydrogen and nitrogen containing discharges emit intense radiation in a broad wavelength region in the VUV. The measured radiant power of individual molecular transitions and atomic lines between 117 nm and 280 nm are compared to those obtained in the visible spectral range and moreover to the RF power supplied to the ICP discharge. In hydrogen plasmas driven at 540 W of RF power up to 110 W are radiated in the VUV, whereas less than 2 W is emitted in the VIS. In nitrogen plasmas the power level of about 25 W is emitted both in the VUV and in the VIS. In hydrogen-nitrogen mixtures, the NH radiation increases the VUV amount. The analysis of molecular and atomic hydrogen emission supported by a collisional radiative model allowed determining plasma parameters and particle densities and thus particle fluxes. A comparison of the fluxes showed that the photon fluxes determined from the measured emission are similar to the ion fluxes, whereas the atomic hydrogen fluxes are by far dominant. Photon fluxes up to 5  ×  1020 m-2 s-1 are obtained, demonstrating that the VUV radiation should not be neglected in surface modifications processes, whereas the radiant power converted to VUV photons is to be considered in power balances. Varying the admixture of nitrogen to hydrogen offers a possibility to tune photon fluxes in the respective wavelength intervals.

  7. The plasma membrane sodium-hydrogen exchanger and its role in physiological and pathophysiological processes.

    PubMed

    Mahnensmith, R L; Aronson, P S

    1985-06-01

    The plasma membranes of most if not all vertebrate cells contain a transport system that mediates the transmembrane exchange of sodium for hydrogen. The kinetic properties of this transport system include a 1:1 stoichiometry, affinity for lithium and ammonium ion in addition to sodium and hydrogen, the ability to function in multiple 1:1 exchange modes involving these four cations, sensitivity to inhibition by amiloride and its analogues, and allosteric regulation by intracellular protons. The plasma membrane sodium-hydrogen exchanger plays a physiological role in the regulation of intracellular pH, the control of cell growth and proliferation, stimulus-response coupling in white cells and platelets, the metabolic response to hormones such as insulin and glucocorticoids, the regulation of cell volume, and the transepithelial absorption and secretion of sodium, hydrogen, bicarbonate and chloride ions, and organic anions. Preliminary evidence raises the possibility that the sodium-hydrogen exchanger may play a pathophysiological role in such diverse conditions as renal acid-base disorders, essential hypertension, cancer, and tissue or organ hypertrophy. Thus, future research on cellular acid-base homeostasis in general, and on plasma membrane sodium-hydrogen exchange in particular, will enhance our understanding of a great variety of physiological and pathophysiological processes.

  8. Remote operation of the GOLEM tokamak with hydrogen and helium plasmas

    NASA Astrophysics Data System (ADS)

    Svoboda, V.; Dvornova, A.; Dejarnac, R.; Prochazka, M.; Zaprianov, S.; Akhmethanov, R.; Bogdanova, M.; Dimitrova, M.; Dimitrov, Zh; Grover, O.; Hlavata, L.; Ivanov, K.; Kruglov, K.; Marinova, P.; Masherov, P.; Mogulkin, A.; Mlynar, J.; Stockel, J.; Volynets, A.

    2016-10-01

    The GOLEM tokamak was operated remotely via Internet connection during the 6th International Workshop and Summer School on Plasma Physics. Performances of hydrogen and helium discharges are compared in this paper. It is found, at similar vacuum conditions, that helium discharges are shorter but the breakdown of the working gas can be quite easily achieved at almost the same loop voltage. The plasma current in helium discharges is slightly lower than in the case of hydrogen. Turbulent fluctuations of the floating potential measured by means of an array of Langmuir probes reveal a noticeably different character in the two discharges.

  9. Hydrogen recovery from the thermal plasma gasification of solid waste.

    PubMed

    Byun, Youngchul; Cho, Moohyun; Chung, Jae Woo; Namkung, Won; Lee, Hyeon Don; Jang, Sung Duk; Kim, Young-Suk; Lee, Jin-Ho; Lee, Carg-Ro; Hwang, Soon-Mo

    2011-06-15

    Thermal plasma gasification has been demonstrated as one of the most effective and environmentally friendly methods for solid waste treatment and energy utilization in many of studies. Therefore, the thermal plasma process of solid waste gasification (paper mill waste, 1.2 ton/day) was applied for the recovery of high purity H(2) (>99.99%). Gases emitted from a gasification furnace equipped with a nontransferred thermal plasma torch were purified using a bag-filter and wet scrubber. Thereafter, the gases, which contained syngas (CO+H(2)), were introduced into a H(2) recovery system, consisting largely of a water gas shift (WGS) unit for the conversion of CO to H(2) and a pressure swing adsorption (PSA) unit for the separation and purification of H(2). It was successfully demonstrated that the thermal plasma process of solid waste gasification, combined with the WGS and PSA, produced high purity H(2) (20 N m(3)/h (400 H(2)-Nm(3)/PMW-ton), up to 99.99%) using a plasma torch with 1.6 MWh/PMW-ton of electricity. The results presented here suggest that the thermal plasma process of solid waste gasification for the production of high purity H(2) may provide a new approach as a future energy infrastructure based on H(2).

  10. Research progress on ionic plasmas generated in an intense hydrogen negative ion source

    SciTech Connect

    Takeiri, Y. Tsumori, K.; Nagaoka, K.; Kaneko, O.; Ikeda, K.; Nakano, H.; Kisaki, M.; Tokuzawa, T.; Osakabe, M.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Sekiguchi, H.; Geng, S.

    2015-04-08

    Characteristics of ionic plasmas, observed in a high-density hydrogen negative ion source, are investigated with a multi-diagnostics system. The ionic plasma, which consists of hydrogen positive- and negative-ions with a significantly low-density of electrons, is generated in the ion extraction region, from which the negative ions are extracted through the plasma grid. The negative ion density, i.e., the ionic plasma density, as high as the order of 1×10{sup 17}m{sup −3}, is measured with cavity ring-down spectroscopy, while the electron density is lower than 1×10{sup 16}m{sup −3}, which is confirmed with millimeter-wave interferometer. Reduction of the negative ion density is observed at the negative ion extraction, and at that time the electron flow into the ionic plasma region is observed to conserve the charge neutrality. Distribution of the plasma potential is measured in the extraction region in the direction normal to the plasma grid surface with a Langmuir probe, and the results suggest that the sheath is formed at the plasma boundary to the plasma grid to which the bias voltage is applied. The beam extraction should drive the negative ion transport in the ionic plasma across the sheath formed on the extraction surface. Larger reduction of the negative ions at the beam extraction is observed in a region above the extraction aperture on the plasma grid, which is confirmed with 2D image measurement of the Hα emission and cavity ring-down spectroscopy. The electron distribution is also measured near the plasma grid surface. These various properties observed in the ionic plasma are discussed.

  11. Variational Average-Atom in Quantum Plasmas (VAAQP) - Recent progress, virial theorem and applications to the equation-of-state of warm dense Be

    NASA Astrophysics Data System (ADS)

    Piron, R.; Blenski, T.

    2011-12-01

    The Variational Average-Atom in Quantum Plasmas (VAAQP) code is based on a fully variational theory of dense plasmas in equilibrium in which the neutrality of the Wigner-Seitz ion sphere is not required, contrary to the INFERNO model. We report on some recent progress in the VAAQP model and numerical code. Three important points of the virial theorem derivation are emphasized and explained. The virial theorem is also used as an important tool allowing us to check the formulas and numerical methods used in the code. Applications of the VAAQP code are shown using as an example the equation-of-state of beryllium in the warm dense matter regime. Comparisons with the INFERNO model, and with available experimental data on the principal Hugoniot are also presented.

  12. Surface modification of optical materials with hydrogen plasma for fabrication of Bragg gratings.

    PubMed

    Salgaeva, Uliana O; Volyncev, Anatoliy B; Mendes, Sergio B

    2016-01-20

    We investigate the hydrogen plasma process as a route for creating Bragg gratings (BGs) on optoelectronic materials such as undoped lithium niobate (LiNbO(3)), proton-exchanged LiNbO(3), and soda-lime glass. Photopatterns (periodic modulations, Λ=323-2000  nm) were created on those substrates and the hydrogen plasma process was investigated for its ability to transfer the microstructures and the underlying mechanisms involved in this process. The diffraction efficiency and surface topology of the BG were characterized, as well as the optical properties of corresponding bulk materials undergoing the same plasma treatment. It is shown that the hydrogen plasma treatment changes the complex refractive index and modifies the surface topology with a volume expansion in the near-surface region, and both features are connected to the appearance of structural defects in the materials. The hydrogen plasma offers unique flexibility and advantages that can be explored for the fabrication of integrated photonic components.

  13. Effects of laser radiation field on energies of hydrogen atom in plasmas

    SciTech Connect

    Bahar, M. K.

    2015-09-15

    In this study, for the first time, the Schrödinger equation with more general exponential cosine screened Coulomb (MGECSC) potential is solved numerically in the presence of laser radiation field within the Ehlotzky approximation using the asymptotic iteration method. The MGECSC potential includes four different potential forms in consideration of different sets of the parameters in the potential. By applying laser field, the total interaction potential of hydrogen atom embedded in plasmas converts to double well-type potential. The plasma screening effects under the influence of laser field as well as confinement effects of laser field on hydrogen atom in Debye and quantum plasmas are investigated by solving the Schrödinger equation with the laser-dressed MGECSC potential. It is resulted that since applying a monochromatic laser field on hydrogen atom embedded in a Debye and quantum plasma causes to shift in the profile of the total interaction potential, the confinement effects of laser field on hydrogen atom in plasmas modeled by the MGECSC potential change localizations of energy states.

  14. Effects of laser radiation field on energies of hydrogen atom in plasmas

    NASA Astrophysics Data System (ADS)

    Bahar, M. K.

    2015-09-01

    In this study, for the first time, the Schrödinger equation with more general exponential cosine screened Coulomb (MGECSC) potential is solved numerically in the presence of laser radiation field within the Ehlotzky approximation using the asymptotic iteration method. The MGECSC potential includes four different potential forms in consideration of different sets of the parameters in the potential. By applying laser field, the total interaction potential of hydrogen atom embedded in plasmas converts to double well-type potential. The plasma screening effects under the influence of laser field as well as confinement effects of laser field on hydrogen atom in Debye and quantum plasmas are investigated by solving the Schrödinger equation with the laser-dressed MGECSC potential. It is resulted that since applying a monochromatic laser field on hydrogen atom embedded in a Debye and quantum plasma causes to shift in the profile of the total interaction potential, the confinement effects of laser field on hydrogen atom in plasmas modeled by the MGECSC potential change localizations of energy states.

  15. Reversed ageing of Fe3O4 nanoparticles by hydrogen plasma

    PubMed Central

    Schmitz-Antoniak, Carolin; Schmitz, Detlef; Warland, Anne; Svechkina, Nataliya; Salamon, Soma; Piamonteze, Cinthia; Wende, Heiko

    2016-01-01

    Magnetite (Fe3O4) nanoparticles suffer from severe ageing effects when exposed to air even when they are dispersed in a solvent limiting their applications. In this work, we show that this ageing can be fully reversed by a hydrogen plasma treatment. By x-ray absorption spectroscopy and its associated magnetic circular dichroism, the electronic structure and magnetic properties were studied before and after the plasma treatment and compared to results of freshly prepared magnetite nanoparticles. While aged magnetite nanoparticles exhibit a more γ-Fe2O3 like behaviour, the hydrogen plasma yields pure Fe3O4 nanoparticles. Monitoring the temperature dependence of the intra-atomic spin dipole contribution to the dichroic spectra gives evidence that the structural, electronic and magnetic properties of plasma treated magnetite nanoparticles can outperform the ones of the freshly prepared batch. PMID:26902789

  16. Combined effect of Debye plasma environment and external electric field on hydrogen atom

    SciTech Connect

    Paul, S.; Ho, Y. K.

    2010-08-15

    We consider weakly coupled plasmas, characterized by Debye-Huckel model potential, and an external electric field along z-axis. Due to plasma environment the energy levels of atom are shifted up, bound states are merged to continuum. For external electric field the excited energy levels also split up; degenerate energy eigenvalues become nondegenerate. In the presence of external electric field, energy levels are shifted up and down, except ground state. The ground state energy value is shifted only down. Therefore, it is very interesting to study the combined effect of plasmas and external electric field on a simple atom (hydrogen). To calculate the energy levels and the corresponding states, we expand the wave function in terms of linear combination of the basis functions. The basis is generated by hydrogenic wave functions. Here, we estimate various plasma surroundings and electric field strengths. We observe converged results for the basis size 45, with angular momentum states up to eight.

  17. Roles of a plasma grid in a negative hydrogen ion source

    SciTech Connect

    Bacal, M.; Sasao, M.; Wada, M.; McAdams, R.

    2015-04-08

    The plasma grid is electrically biased with respect to other parts of source chamber wall in both volume sources and sources seeded with alkali metals. The roles of the plasma grid in these two kinds of sources will be described. The main functions of the plasma grid in volume sources are: optimizing the extracted negative ion current, reducing the co-extracted electron current, controlling the axial plasma potential profile, recycling the hydrogen atoms to molecules, concentrating the negative ions near its surface and, when biased positive, depleting the electron population near its surface. These functions are maintained in the sources seeded with alkali metals. However an additional function appears in the Cs seeded sources, namely direct emission of negative ions under positive ion and neutral hydrogen bombardment.

  18. Stability and etching of titanium oxynitride films in hydrogen microwave plasma

    SciTech Connect

    Do Hien; Yen, Tzu-Chun; Chang Li

    2013-07-15

    Epitaxial titanium oxynitride (TiNO) films deposited on MgO by pulsed laser deposition were treated in hydrogen microwave plasma. Scanning electron microscopy and x-ray photoelectron spectroscopy were used to examine the stability and etching of TiNO which strongly depended on hydrogen gas pressure. TiNO was very chemically stable and remained with good crystallinity under hydrogen pressure below 5300 Pa. With increase of pressure, it may lead to the formation of etch pits in inverse pyramid shape. The etch mechanism as well as the effects of gas pressure and etching time are also presented.

  19. Observed Multi-Decade DD and DT Z-Pinch Fusion Rate Scaling in 5 Dense Plasma Focus Fusion Machines

    SciTech Connect

    Hagen, E. C.; Lowe, D. R.; O'Brien, R.; Meehan, B. T.

    2013-06-18

    Dense Plasma Focus (DPF) machines are in use worldwide or a wide variety of applications; one of these is to produce intense, short bursts of fusion via r-Z pinch heating and compression of a working gas. We have designed and constructed a series of these, ranging from portable to a maximum energy storage capacity of 2 MJ. Fusion rates from 5 DPF pulsed fusion generators have been measured in a single laboratory using calibrated activation detectors. Measured rates range from ~ 1015 to more than 1019 fusions per second have been measured. Fusion rates from the intense short (20 – 50 ns) periods of production were inferred from measurement of neutron production using both calibrated activation detectors and scintillator-PMT neutron time of flight (NTOF) detectors. The NTOF detectors are arranged to measure neutrons versus time over flight paths of 30 Meters. Fusion rate scaling versus energy and current will be discussed. Data showing observed fusion cutoff at D-D fusion yield levels of approximately 1*1012, and corresponding tube currents of ~ 3 MA will be shown. Energy asymmetry of product neutrons will also be discussed. Data from the NTOF lines of sight have been used to measure energy asymmetries of the fusion neutrons. From this, center of mass energies for the D(d,n)3He reaction are inferred. A novel re-entrant chamber that allows extremely high single pulse neutron doses (> 109 neutrons/cm2 in 50 ns) to be supplied to samples will be described. Machine characteristics and detector types will be discussed.

  20. Isotropic and anisotropic components of neutron emissions at the FN-II and PACO dense plasma focus devices

    NASA Astrophysics Data System (ADS)

    Castillo, F.; Herrera, J. J. E.; Rangel, J.; Milanese, M.; Moroso, R.; Pouzo, J.; Golzarri, J. I.; Espinosa, G.

    2003-03-01

    The average angular distribution of neutron emissions has been measured in the Fuego Nuevo II (FN-II) dense plasma focus device (5 kJ) by means of CR-39 plastic nuclear track detectors. When pure deuterium is used as the filling gas, the data can be adjusted to a Gaussian function, related to anisotropic emission, superposed on a constant pedestal, related to isotropic emission. When deuterium-argon admixtures are used, the anisotropic contribution is best represented by a parabola. The same analysis is applied to previously reported results, for fewer shots, in pure deuterium from the PACO device, which is similar in size to the FN-II. In both devices the anisotropic component is smaller than the isotropic one, but with different features. In PACO the anisotropic component is concentrated on a large narrow beam around the axis, but its contribution to the total neutron yield is significantly smaller than in the FN-II, where the anisotropic component spreads over a wider range. The neutron flux per shot is monitored in both devices with calibrated silver activation detectors, at 20° and at 90° from the axis. The average values of the neutron flux at these two angles are used, along with the angular distributions obtained form the track detectors, in order to estimate the absolute neutron yield of both the isotropic and the anisotropic contributions. From examining different groups of shots, it is found that the shape of the angular distribution is important in the estimation of anisotropy, and that the value usually reported, as the ratio of neutron counts head-on and side-on, as measured by activation counters, may be misleading.

  1. Plasma reforming and partial oxidation of hydrocarbon fuel vapor to produce synthesis gas and/or hydrogen gas

    DOEpatents

    Kong, Peter C.; Detering, Brent A.

    2003-08-19

    Methods and systems for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  2. Plasma Reforming And Partial Oxidation Of Hydrocarbon Fuel Vapor To Produce Synthesis Gas And/Or Hydrogen Gas

    DOEpatents

    Kong, Peter C.; Detering, Brent A.

    2004-10-19

    Methods and systems are disclosed for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  3. Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

    NASA Astrophysics Data System (ADS)

    Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-09-01

    Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

  4. Monitoring Surface Condition of Plasma Grid of a Negative Hydrogen Ion Source

    SciTech Connect

    Wada, M.; Kasuya, T.; Tokushige, S.; Kenmotsu, T.

    2011-09-26

    Surface condition of a plasma grid in a negative hydrogen ion source is controlled so as to maximize the beam current under a discharge operation with introducing Cs into the ion source. Photoelectric current induced by laser beams incident on the plasma grid can produce a signal to monitor the surface condition, but the signal detection can be easily hindered by plasma noise. Reduction in size of a detection electrode embedded in the plasma grid can improve signal-to-noise ratio of the photoelectric current from the electrode. To evaluate the feasibility of monitoring surface condition of a plasma gird by utilizing photoelectric effect, a small experimental setup capable of determining quantum yields of a surface in a cesiated plasma environment is being assembled. Some preliminary test results of the apparatus utilizing oxide cathodes are reported.

  5. Nuclear-plus-interference-scattering effect on the energy deposition of multi-MeV protons in a dense Be plasma.

    PubMed

    Wang, Zhigang; Fu, Zhenguo; He, Bin; Hu, Zehua; Zhang, Ping

    2016-09-01

    The nuclear plus interference scattering (NIS) effect on the stopping power of hot dense beryllium (Be) plasma for multi-MeV protons is theoretically investigated by using the generalized Brown-Preston-Singleton (BPS) model, in which a NIS term is taken into account. The analytical formula of the NIS term is detailedly derived. By using this formula, the density and temperature dependence of the NIS effect is numerically studied, and the results show that the NIS effect becomes more and more important with increasing the plasma temperature or density. Different from the cases of protons traveling through the deuterium-tritium plasmas, for a Be plasma, a prominent oscillation valley structure is observed in the NIS term when the proton's energy is close to E_{p}=7MeV. Furthermore, the penetration distance is remarkably reduced when the NIS term is considered.

  6. Nuclear-plus-interference-scattering effect on the energy deposition of multi-MeV protons in a dense Be plasma

    NASA Astrophysics Data System (ADS)

    Wang, Zhigang; Fu, Zhenguo; He, Bin; Hu, Zehua; Zhang, Ping

    2016-09-01

    The nuclear plus interference scattering (NIS) effect on the stopping power of hot dense beryllium (Be) plasma for multi-MeV protons is theoretically investigated by using the generalized Brown-Preston-Singleton (BPS) model, in which a NIS term is taken into account. The analytical formula of the NIS term is detailedly derived. By using this formula, the density and temperature dependence of the NIS effect is numerically studied, and the results show that the NIS effect becomes more and more important with increasing the plasma temperature or density. Different from the cases of protons traveling through the deuterium-tritium plasmas, for a Be plasma, a prominent oscillation valley structure is observed in the NIS term when the proton's energy is close to Ep=7 MeV . Furthermore, the penetration distance is remarkably reduced when the NIS term is considered.

  7. Low energy, high power hydrogen neutral beam for plasma heating

    SciTech Connect

    Deichuli, P.; Davydenko, V.; Ivanov, A. Mishagin, V.; Sorokin, A.; Stupishin, N.; Korepanov, S.; Smirnov, A.

    2015-11-15

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  8. Confinement effects of magnetic field on two-dimensional hydrogen atom in plasmas

    SciTech Connect

    Bahar, M. K.; Soylu, A.

    2015-05-15

    In this study, for the first time, the Schrödinger equation with more general exponential cosine screened Coulomb (MGECSC) potential is solved numerically in the presence and in the absence of an external magnetic field within two-dimensional formalism using the asymptotic iteration method. The MGECSC potential includes four different potential forms when considering different sets of the parameters in the potential. The plasma screening effects in the weak and strong magnetic field regimes as well as the confinement effects of magnetic field on the two-dimensional hydrogen atom in Debye and quantum plasmas are investigated by solving the corresponding equations. It is found that applying a uniform magnetic field on the hydrogen atom embedded in a plasma leads to change in the profile of the total interaction potential. Thus, confinement effects of magnetic field on hydrogen atom embedded in Debye and quantum plasmas modeled by a MGECSC potential lead to shift bound state energies. This effect would be important to isolate the plasma from the external environment in the experimental applications of plasma physics.

  9. Confinement effects of magnetic field on two-dimensional hydrogen atom in plasmas

    NASA Astrophysics Data System (ADS)

    Bahar, M. K.; Soylu, A.

    2015-05-01

    In this study, for the first time, the Schrödinger equation with more general exponential cosine screened Coulomb (MGECSC) potential is solved numerically in the presence and in the absence of an external magnetic field within two-dimensional formalism using the asymptotic iteration method. The MGECSC potential includes four different potential forms when considering different sets of the parameters in the potential. The plasma screening effects in the weak and strong magnetic field regimes as well as the confinement effects of magnetic field on the two-dimensional hydrogen atom in Debye and quantum plasmas are investigated by solving the corresponding equations. It is found that applying a uniform magnetic field on the hydrogen atom embedded in a plasma leads to change in the profile of the total interaction potential. Thus, confinement effects of magnetic field on hydrogen atom embedded in Debye and quantum plasmas modeled by a MGECSC potential lead to shift bound state energies. This effect would be important to isolate the plasma from the external environment in the experimental applications of plasma physics.

  10. Hydrogen production in a radio-frequency plasma source operating on water vapor

    NASA Astrophysics Data System (ADS)

    Nguyen, Son-Ca Viet Thi

    The global energy and climate challenges have motivated development of innovative techniques to satisfy energy demand while minimizing emissions. To this end, hydrogen as an alternative energy carrier in the transportation sector is an attractive option. In addition, there is already a great need for hydrogen gas in several industrial processes such as hydro-cracking of crude oil to produce gasoline and production of ammonia and methanol. The current dominant methods of hydrogen production from fossil fuels are well-developed and have reached relatively high energy efficiencies (up to 85%), but these methods rely on non-renewable natural resources and produce carbon dioxide emissions. This work investigates the feasibility of hydrogen production by dissociating water molecules in a radio-frequency (RF) plasma discharge. In addition to the widespread usage of hydrogen gas, applications of water plasma have permeated in many areas of research, and information on basic behaviors of a water plasma discharge will provide fruitful insights for other researchers. An RF plasma source equipped with a double-helix antenna (m = 1 mode) and an applied axial magnetic field is designed to operate on water vapor. It is shown that water molecules are being dissociated in the discharge. Experimental results show that the rate of hydrogen production increases linearly with RF power in the absence of the applied axial magnetic field. With the magnetic field, the rate of hydrogen production increases from 250 to 500 W, and begins to saturate with RF power. Despite this saturation, it is shown that hydrogen increases with magnetic field strength at a fixed RF power. Further, the rate of hydrogen production increases with water input flow rate up to 100 sccm for a fixed RF power level, and begins to decrease at 125 sccm. This dissertation characterizes the rate of hydrogen production and plasma properties as a function of RF power, applied B-field strength, and water input flow rate. A

  11. Transition of single-walled carbon nanotubes from metallic to semiconducting in field-effect transistors by hydrogen plasma treatment.

    PubMed

    Zheng, Gang; Li, Qunqing; Jiang, Kaili; Zhang, Xiaobo; Chen, Jia; Ren, Zheng; Fan, Shoushan

    2007-06-01

    We report hydrogen plasma treatment results on converting the metallic single-walled carbon nanotubes to semiconducting single-walled carbon nanotubes. We found that the as-grown single-walled carbon nanotubes (SWNTs) can be sorted as three groups which behave as metallic, as-metallic, and semiconducting SWNTs. These three groups have different changes under hydrogen plasma treatment and successive annealing process. The SWNTs can be easily hydrogenated in the hydrogen plasma environment and the as-metallic SWNTs can be transformed to semiconducting SWNTs. The successive annealing process can break the C-H bond, so the conversion is reversible.

  12. On Asymmetry of Hydrogen Spectral Lines in Nonequlibrium Plasmas

    SciTech Connect

    Demura, A. V.; Demchenko, G. V.; Nikolic, D.

    2008-10-22

    The Standard Theory (ST) of hydrogen spectral lines Stark broadening is applied within many-body approach to detailed description of profile asymmetry simultaneously accounting for the quadrupole interaction, quadratic Stark effect shifts and corrections to oscillator strengths. The influence of electronic collision shifts and impact widths, trivial asymmetry, the Boltzmann and dipole intensity scaling factors are studied as well. The consistent inclusion of the latter two factors in ST frames requests the line contour redefinition to avoid divergence. It is demonstrated that the asymmetry of hydrogen spectral lines is the many-parametric sensitive function of broadening mechanisms. The comparison with the precision experiment on stabilized arc data for H{sub {beta}} line has shown good coincidence within assumption of nonequilibrium between electrons and heavy neutral particles.

  13. Full densification of inkjet-printed copper conductive tracks on a flexible substrate utilizing a hydrogen plasma sintering

    NASA Astrophysics Data System (ADS)

    Kwon, Young-Tae; Lee, Young-In; Kim, Seil; Lee, Kun-Jae; Choa, Yong-Ho

    2017-02-01

    Low temperature sintering techniques are crucial in developing flexible printed electronics. In this work, we demonstrate a novel hydrogen plasma sintering method that achieves a full reduction and densification of inkjet-printed patterns using a copper complex ion ink. After inkjet printing on polyethylene terephthalate (PET) substrates, both hydrogen plasma and conventional hydrogen thermal treatment were employed to compare the resulting microstructures, electrical properties and anti-oxidation behavior. The plasma treated pattern shows a fully densified microstructure with a resistivity of 3.23 μΩ cm, while the thermally treated pattern shows a relatively poor microstructure and high resistivity. In addition, the hydrogen plasma-treated copper pattern retains its electrical resistivity for one month without any significant decrease. This novel hydrogen plasma sintering technique could be used to produce conductive patterns with excellent electrical properties, allowing for highly reliable flexible printed electronics.

  14. Interfacial modification of amorphous substrates for microcrystalline silicon growth with in situ hydrogen plasma pretreatment

    NASA Astrophysics Data System (ADS)

    Park, Young-Bae; Rhee, Shi-Woo; Li, Xiaodong

    2005-10-01

    Microcrystalline silicon (μc-Si:H) films have been deposited onto hydrogenated and amorphous Si-rich silicon nitride and thermal oxide substrates with silane (SiH4)-hydrogen (H2) in remote plasma-enhanced chemical vapor deposition (RPECVD) at 250 °C, and these films have been investigated. It is found that in situ hydrogen plasma pretreatment of the amorphous substrates prior to μc-Si:H deposition is effective in reducing the interfacial amorphous transition region. It is believed that this hydrogen plasma pretreatment gives adsorption and nucleation sites by breaking weak Si-N and Si-Si bonds and also removes native Si-O x and hydrocarbon impurities. In the case of SiNx:H surface, surface roughening from atomic hydrogen etching and surface cleaning effects are greater than those for stable thermal oxide. Surface crystallization at the initial stage of the growth can be obtained on amorphous substrate at low temperature without an a-Si transition layer.

  15. Coal pyrolysis to acetylene using dc hydrogen plasma torch: effects of system variables on acetylene concentration

    NASA Astrophysics Data System (ADS)

    Chen, Longwei; Meng, Yuedong; Shen, Jie; Shu, Xingsheng; Fang, Shidong; Xiong, Xinyang

    2009-03-01

    In order to unveil the inner mechanisms that determine acetylene concentration, experimental studies on the effect of several parameters such as plasma torch power, hydrogen flux and coal flux were carried out from coal pyrolysis in a dc plasma torch. Xinjiang long flame coals including volatile constituents at a level of about 42% were used in the experiment. Under the following experimental conditions, namely plasma torch power, hydrogen flow rate and pulverized coal feed speed of 2.12 MW, 32 kg h-1 and 900 kg h-1, respectively, acetylene volume concentration of about 9.4% was achieved. The experimental results indicate that parameters such as plasma torch power and coal flux play important roles in the formation of acetylene. Acetylene concentration increases inconspicuously with hydrogen flux. A chemical thermodynamic equilibrium model using the free energy method is introduced in this paper to numerically simulate each experimental condition. The numerical results are qualitatively consistent with the experimental results. Two parameters, i.e. the gas temperature and the ratio of hydrogen/carbon, are considered to be the dominant and independent factors that determine acetylene concentration.

  16. Factors Affecting VUV Emission Spectrum near Lyman-{alpha} from a Hydrogen Plasma Source

    SciTech Connect

    Ogino, K.; Kasuya, T.; Shimamoto, S.; Wada, M.; Kimura, Y.; Nishiura, M.

    2011-09-26

    Vacuum ultra violet (VUV) emission spectra from plasmas near walls of different metallic materials were measured to estimate the effect upon the local production rate of vibrational excited hydrogen molecules due to plasma wall interaction. Among Cu, Mo, Ni, Ta and Ti, the intensity of band spectrum around Lyman-{alpha} had become the largest when Cu wall was used while it was the smallest for Ti. The role of particle reflection from the plasma electrode surface upon the H{sup -} production by a pure electron volume process is discussed.

  17. Atomic hydrogen and diatomic titanium-monoxide molecular spectroscopy in laser-induced plasma

    NASA Astrophysics Data System (ADS)

    Parigger, Christian G.; Woods, Alexander C.

    2017-03-01

    This article gives a brief review of experimental studies of hydrogen Balmer series emission spectra. Ongoing research aims to evaluate early plasma evolution following optical breakdown in laboratory air. Of interest is as well laser ablation of metallic titanium and characterization of plasma evolution. Emission of titanium monoxide is discussed together with modeling of diatomic spectra to infer temperature. The behavior of titanium particles in plasma draws research interests ranging from the modeling of stellar atmospheres to the enhancement of thin film production via pulsed laser deposition.

  18. Plasma Outages in Pulsed, High-Power RF Hydrogen Ion Sources

    NASA Astrophysics Data System (ADS)

    Stockli, Martin; Han, Baoxi; Murray, Syd; Pennisi, Terry; Piller, Chip; Santana, Manuel; Welton, Robert

    2011-04-01

    Pulsed, high-power RF ion sources are needed to produce copious amounts of negative H-ions for high-power accelerators with charge-changing injection schemes. When increasing the RF power, the plasma inductance changes the RF resonance, which drifts away from the low-power resonance. When the RF circuit is tuned to maximize the (pulsed) plasma power, the (off-resonance) power at the beginning of the pulse is reduced. If the induced electric fields fall below the breakdown strength of the hydrogen gas, the plasma fails to develop. This can be avoided with a compromise tune and/or by increasing the inductance of the resonant circuit. However, the breakdown strength of the hydrogen gas increases with time due to the gradual decrease of the electron-rich plasma impurities, which causes plasma outages after weeks of reliable operation. In this paper we discuss the success of different mitigations that were tested and implemented to overcome this fundamental problem of pulsed, high-power RF hydrogen ion sources.

  19. Probe of hydrogen atom in plasmas with magnetic, electric, and Aharonov-Bohm flux fields

    NASA Astrophysics Data System (ADS)

    Bahar, M. K.; Soylu, A.

    2016-09-01

    In this study, for the first time, the combined effects of external magnetic, electric, and Aharonov-Bohm (AB) flux fields on quantum levels of the hydrogen atom embedded in Debye and quantum plasmas modeled by the more general exponential cosine screened Coulomb (MGECSC) potential are investigated within cylindrical coordinate formalism using the asymptotic iteration method. The MGECSC potential includes four different potential forms when considering different sets of the parameters in the potential. The corresponding Schrödinger equation is solved numerically in order to examine both strong and weak regimes and confinement effects of external fields. The influence of screening parameters of the MGECSC potential on quantum levels of the hydrogen atom is also studied in detail in the presence of external magnetic, electric, and AB flux fields. As it is possible to model both Debye and quantum plasmas by using screening parameters in the MGECSC potential, the effects of each plasma environment on quantum levels of the hydrogen atom are also considered in the external fields. It is observed that there are important results of external fields on the total interaction potential profile, and the most dominant one in these fields is the magnetic field. Furthermore, the effects of confinement on the physical state of the plasma environment is a subject of this study. These details would be important in experimental and theoretical investigations in plasma and atomic physics fields.

  20. Novel Composite Hydrogen-Permeable Membranes for Non-Thermal Plasma Reactors for the Decomposition of Hydrogen Sulfide

    SciTech Connect

    Morris D. Argyle; John F. Ackerman; Suresh Muknahallipatna; Jerry C. Hamann; Stanislaw Legowski; Guibling Zhao; Ji-Jun Zhang; Sanil John

    2005-10-01

    The goal of this experimental project is to design and fabricate a reactor and membrane test cell to dissociate hydrogen sulfide (H{sub 2}S) in a non-thermal plasma and recover hydrogen (H{sub 2}) through a superpermeable multi-layer membrane. Superpermeability of hydrogen atoms (H) has been reported by some researchers using membranes made of Group V transition metals (niobium, tantalum, vanadium, and their alloys), although it has yet to be confirmed in this study. A pulsed corona discharge (PCD) reactor has been fabricated and used to dissociate H{sub 2}S into hydrogen and sulfur. A nonthermal plasma cannot be produced in pure H{sub 2}S with our reactor geometry, even at discharge voltages of up to 30 kV, because of the high dielectric strength of pure H{sub 2}S ({approx}2.9 times higher than air). Therefore, H{sub 2}S was diluted in another gas with lower breakdown voltage (or dielectric strength). Breakdown voltages of H{sub 2}S in four balance gases (Ar, He, N{sub 2} and H{sub 2}) have been measured at different H{sub 2}S concentrations and pressures. Breakdown voltages are proportional to the partial pressure of H{sub 2}S and the balance gas. H{sub 2}S conversion and the reaction energy efficiency depend on the balance gas and H{sub 2}S inlet concentrations. With increasing H{sub 2}S concentrations, H{sub 2}S conversion initially increases, reaches a maximum, and then decreases. H{sub 2}S conversion in atomic balance gases, such as Ar and He, is more efficient than that in diatomic balance gases, such as N{sub 2} and H{sub 2}. These observations can be explained by the proposed reaction mechanism of H{sub 2}S dissociation in different balance gases. The results show that nonthermal plasmas are effective for dissociating H{sub 2}S into hydrogen and sulfur.