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Solid hydrogen and astrophysic

  1. Feb 18, 2008 #1


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    Solid hydrogen and astrophysic

    I then did a search for “ionization” and found dozens of references in astrophysic.
    It was a surprise (to me), to find that the models of planets, stars, all depend on knowing the properties of hydrogen as a solid.
    Sure enough,….. the experiments on “warm dense matter” (WDM) are having an impact on astrophysics.

    Is there a paper that looks at Jupiter and by the process of elimination arrive at the properties of solid hydrogen which could help in the lab. experiments?

    Modeling Pressure-Ionization of Hydrogen in the Context of Astrophysics
    Authors: D. Saumon, G. Chabrier, D.J. Wagner, X. Xie
    (Submitted on 9 Sep 1999)
    note: not to be ignored
    Whether pressure ionization of H occurs continuously or through a plasma phase transition PPT remains one of the major unanswered questions in our understanding of the properties of matter under extreme conditions. The answer has profound astrophysical implications.
    The recent experiments [5,29] have revealed that the current theories for dense fluid hydrogen strongly disagree with each other in the regime of pressure dissociation/ionization.
    The guidance of experimental data is therefore essential to the development of a good understanding of this phenomenon. This need is most acute for models based on the chemical picture, which depend on experiments for the determination of effective pair
    potentials. The chemical picture is well-suited for the computation of large EOS tables for astrophysical applications, but models must be calibrated with experimental data if they are to be reliable in the difficult regime of pressure ionization. From this perspective, the recent shock-compression data are extremely valuable and it is hoped that this part of the phase diagram will soon be better charted by new experiments.
    Quantum-statistical equation-of-state models of dense plasmas: high-pressure Hugoniot shock adiabats
    Authors: Jean-Christophe Pain
    (Submitted on 25 Jun 2007)
    The need for suitable equation of state (EOS) of high-energydensity matter becomes crucial. The thermodynamics and the hydrodynamics of these systems can not be predicted without a knowledge of the EOS which describes how a material reacts to pressure.

    In the present work, we consider strongly coupled (non ideal) plasmas, characterized by a high density and/or a low temperature. In such plasmas, ions are strongly correlated, electrons are partially degenerate, the De Broglie wavelength of the electron becomes of the same order of the interparticle distance, …
    Equation of state for dense hydrogen and plasma phase transition
    Authors: Bastian Holst, Nadine Nettelmann, Ronald Redmer
    (Submitted on 2 Apr 2007)
    In this paper we present new results for the equation-of-state (EOS) of dense hydrogen within the chemical picture.
    The equation-of-state data is used to calculate the pressure and temperature profiles for the interior of Jupiter.
    Warm dense hydrogen is considered as a partially ionized plasma in the chemical picture.
    According to the concept of reduced volume, point-like particles cannot penetrate into the volume occupied by atoms and molecules.
    The PPT is an instability driven by the nonmetal-to-metal transition (pressure ionization).
    Idealized Slab Plasma approach for the study of Warm Dense Matter
    Authors: A. Ng (LLNL), T. Ao, F. Perrot, M. W. C. Dharma-wardana (NRC Canada), M. E. Foord (LLNL)
    (Submitted on 10 May 2005)
    To allow the study of well-defined WDM states, we have introduced the concept of idealized-slab plasmas that can be realized in the laboratory via (i) the isochoric heating of a solid and (ii) the propagation of a shock wave in a solid.
    Free-energy model for fluid helium at high density
    Authors: Christophe Winisdoerffer (Leicester University UK, ENS Lyon France), Gilles Chabrier (ENS Lyon France)
    (Submitted on 6 Dec 2004)
    These predictions and this phase diagram provide a guide for future dynamical experiments or numerical first-principle calculations aimed at studying the properties of helium at very high density, in particular its metallization.
    p. 5
    For a density n, each atom has a typical available volume n−1/3 so that, as density increases, the levels associated with the highest eigenvalues will move into the continuum. When the density is high enough to disturb even the ground-state, the electrons can no longer remain bound to the nuclei: this is the pressure ionization phenomenon. We have included the effect of the interactions of surrounding particles on the internal partition function of helium within the so-called occupation probability formalism [19] (OPF). The OPF ensures the statistical-mechanical consistency between the configurational free-energy characterizing the interactions between atoms, Fconf , and the internal free-energy contribution, Fint. The OPF has been extensively presented in various papers (see e.g. [20])
    Dense astrophysical plasmas
    Authors: G. Chabrier (ENS-Lyon), F. Douchin (ENS-Lyon), A. Y. Potekhin (Ioffe Inst., St.-Petersburg)
    (Submitted on 20 Nov 2002)
    We briefly examine the properties of dense plasmas characteristic of the atmospheres of neutron stars and of the interior of massive white dwarfs. These astrophysical bodies are natural laboratories to study respectively the problem of pressure ionization of hydrogen in a strong magnetic field and the crystallization of the quantum one-component-plasma at finite temperature.
    Liquid metallic hydrogen and the structure of brown dwarfs and giant planets
    Authors: W. B. Hubbard, T. Guillot, J.I. Lunine, A. Burrows, D. Saumon, M.S. Marley, R.S. Freedman
    (Submitted on 2 Mar 1997)
    Electron-degenerate, pressure-ionized hydrogen (usually referred to as metallic hydrogen) is the principal constituent of brown dwarfs, the long-sought objects which lie in the mass range between the lowest-mass stars (about eighty times the mass of Jupiter) and the giant planets. The thermodynamics and transport properties of metallic hydrogen are important for understanding the properties of these objects, which, unlike stars, continually and slowly cool from initial nondegenerate (gaseous) states.
    … developments in high-pressure technology have allowed new experimental studies of hydrogen in the megabar pressure range7, and developments in high pressure theory have given new information about possible phase transitions in hydrogen in the relevant pressure range8.
    … The relevant parts of the hydrogen phase diagram are shown in Fig. 1. This diagram is computed assuming pure hydrogen
    … The solid circle shows an experimentally-observed transition to a metallic state of hydrogen at P = 1.4 Mbar and T = 3000 K.
    Dense plasmas in astrophysics: from giant planets to neutron stars
    Authors: G. Chabrier (Ecole Normale Superieure de Lyon, CRAL), D. Saumon (LANL), A. Potekhin (Ioffe Physico-Technical Institute, St Petersburg)
    (Submitted on 29 Nov 2005)

    We briefly examine the properties of dense plasmas characteristic of the interior of giant planets and the atmospheres of neutron stars. Special attention is devoted to the equation of state of hydrogen and helium at high density and to the effect of magnetic fields on the properties of dense matter.
    Magnetic Hydrogen Atmosphere Models and the Neutron Star RX J1856.5-3754
    Authors: Wynn C. G. Ho, David L. Kaplan, Philip Chang, Matthew van Adelsberg, Alexander Y. Potekhin
    (Submitted on 6 Dec 2006)
    RX J1856.5-3754 is one of the brightest nearby isolated neutron stars, and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain the data. We show that our latest models of a thin, magnetic, partially ionized hydrogen atmosphere on top of a condensed surface can fit the entire spectrum, from X-rays to optical, of RX J1856.5-3754, within the uncertainties.
    High Energy Density (HED) Science

    Web Sites for high energy density physics and accelerators

    Science at the Extremes
    When laboratory experiments begin at the National Ignition Facility in 2010, researchers will be able for the first time to study the effects on matter of the extreme temperatures, pressures and densities that exist naturally only in the stars and deep inside the planets. Results from this relatively new field of research, known as high energy density (HED) science, will mark the dawn of a new era of science. HED experiments at NIF promise to revolutionize our understanding of astrophysics and space physics, hydrodynamics, nuclear astrophysics, material properties, plasma physics, nonlinear optical physics, radiation sources and radiative properties and other areas of science.
    high energy density (HED) physics

    Creating a miniature star on Earth: that's the goal of the National Ignition Facility (NIF), the world's largest laser. When completed in 2009, NIF will focus the intense energy of 192 giant laser beams on a BB-sized target filled with hydrogen fuel – fusing, or igniting, the hydrogen atoms' nuclei.
    Understanding the Universe
    Some of humankind's greatest intellectual challenges have to do with understanding how the universe began, how it works, and how it will end. A recent study by the National Research Council, Connecting Quarks to the Cosmos, produced a list of eleven questions that are crucial to advancing this understanding. Research at the National Ignition Facility could help answer five of these questions:
    What is the Nature Of Dark Energy?
    Did Einstein Have the Last Word on Gravity?
    How Do Cosmic Accelerators Work And What Are They Accelerating?
    What Are the New States of Matter at Exceedingly High Density and Temperature?
    How Were the Elements from Iron to Uranium Made?
    Challenges in High Energy Density Physics:
    Plasma Physics in the 21st Century

    April 19, 2006

    High Energy Density Science Instrument
    PURPOSE: The High Energy Density (HED) Science instrument at the LCLS will enable the detailed study of states of matter created when normal condensed matter is suddenly heated to very high temperatures, well above melting.
    During the brief period (picoseconds) before this matter flies apart, it can form transient phases with properties very different both from the low-temperature condensed phase and from the high-temperature rarified plasma phase. These so-called HED phases are of interest to scientists studying astrophysics, planetary physics, fusion energy and the transition region from condensed matter to hot dense plasmas. Studying them experimentally has been nearly impossible in the past, and theoretical treatment is so complex as to be unreliable.
  2. jcsd
  3. Feb 20, 2008 #2


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    I've got other questions ... for Cosmology ... see ya!
  4. Feb 22, 2008 #3


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    new reference
    Properties of Dense Fluid Hydrogen and Helium in Giant Gas Planets
    Authors: Jan Vorberger, Isaac Tamblyn, Stanimir A. Bonev, Burkhard Militzer
    (Submitted on 15 Jan 2007)
    The physical system reminiscent to the inner mantle of Jupiter, shown in Fig. 1b), can be characterized
    as a metallic fluid. The density is much higher, molecules are dissociated as a result of the increased pressure.
    The electrons are delocalized as a result of the Pauli exclusion principle and form an electron cloud that extends through the simulation cell.
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