Thomson scattering from laser plasmas

Glenzer, S. H.; Alley, William E.; Estabrook, K. G.; Groot, J. S. De; Haines, M. G.; Hammer, J. H.; Jadaud, J. P.; MacGowan, B. J.; Moody, J. D.; Rozmus, W.; Suter, L. J.; Weiland, Timothy L.; Williams, E. A.

doi:10.1063/1.873499

Cited by 142 publications

(104 citation statements)

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“…Large magnetic fields -ranging from tens of kilogauss to a megagauss -have been inferred to be important in indirect drive ICF experiments [8,9]. Thus the effect of B-fields on the heat transport in long-pulse laser plasma interactions must be better characterized.…”

Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

“…Whether the heat flow in the plasma is given by Braginskii directly affects the uniformity of the hohlraum conditions which, in turn, can affect the drive uniformity of the capsule and so the fusion yield. The break down of classical heat transport in laser plasmas has been shown to be important in experimental measurements by Hawreliak et al [6] and Gregori et al [7] over nanosecond time-scales.Large magnetic fields -ranging from tens of kilogauss to a megagauss -have been inferred to be important in indirect drive ICF experiments [8,9]. Thus the effect of B-fields on the heat transport in long-pulse laser plasma interactions must be better characterized.…”

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Magnetic Cavitation and the Reemergence of Nonlocal Transport in Laser Plasmas

2008

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We present the first fully kinetic Vlasov-Fokker-Planck simulations of nanosecond laser-plasma interactions including self-consistent magnetic fields and hydrodynamic plasma expansion. For the largest magnetic fields externally applied to long-pulse laser-gas jet experiments (12T). A significant degree of cavitation of the B-field (>40%) will be shown to occur from the laser heated region in under half a nanosecond. This is due to the Nernst effect and leads to the re-emergence of nonlocality even if the initial value of the magnetic field strength is sufficient to localize the transport. PACS numbers: Valid PACS appear hereRecent interest in inertial confinement fusion (ICF) with the near-completion of the National Ignition Facility (NIF) [1], and in magnetic-reconnection in the novel high energy-density regime [2,3], has brought longpulse laser solid interactions back to the forefront of plasma physics. Magnetohydrodynamics (using Braginskii's classical transport theory [4,5]) is the most commonly employed theoretical model in the simulation of such experiments. The validity of this model to many of these experiments is poorly understood. This is of particular interest to indirect drive ICF [1]. In this scheme a deuterium-tritium fusion capsule is placed in a hohlraum (hollow chamber) of high Z material. This hohlraum generally contains an initially homogeneous under-dense gasfill. The hohlraum wall and gas-fill are heated by many long-pulse lasers creating a plasma. This emits x-rays which drive the compression of the capsule. Whether the heat flow in the plasma is given by Braginskii directly affects the uniformity of the hohlraum conditions which, in turn, can affect the drive uniformity of the capsule and so the fusion yield. The break down of classical heat transport in laser plasmas has been shown to be important in experimental measurements by Hawreliak et al [6] and Gregori et al [7] over nanosecond time-scales.Large magnetic fields -ranging from tens of kilogauss to a megagauss -have been inferred to be important in indirect drive ICF experiments [8,9]. Thus the effect of B-fields on the heat transport in long-pulse laser plasma interactions must be better characterized. Magnetic fields can act to suppress heat flow (by reducing the mobility of the heat-carrying electrons as the Larmor radius becomes smaller than the mean free path) and redirect it. However, this letter is concerned with the fact that B-fields may suppress the breakdown of Braginskii's transport theory. This has recently been addressed in an experiment relevant to a hohlraum gas-fill [10]. The evolution of the magnetic field determines in which regions classical theory is valid at a given time. Under the conditions investigated by Froula et al [10] the B-field may evolve by advecting by 'frozen-in' flow at the plasma's bulk flow velocity or by the Nernst effect [11] (with a velocity v N = 2q e /5n e T e which is proportional to the heat flow [12]). The Nernst effect is often not considered in the modeling of long-pulse interactions an...

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Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

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confidence: 99%

Magnetic Cavitation and the Reemergence of Nonlocal Transport in Laser Plasmas

2008

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“…The blow-off quickly fills the interior of an initially empty (optically thin) hohlraum, leading to early on-axis plasma stagnation [3][4][5][6][7][8]. The stagnated plasma has high pressure and can asymmetrically compress the capsule.…”

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confidence: 99%

“…The tolerable drive asymmetry of an implosion, in a time-integrated sense, is less than 1-2% and depends on the ignition margin [3,4]. In the indirect-drive approach to ICF, low-mode-number implosion asymmetries are a major concern because the quasi-uniform hohlraum radiation field provides drive with minimal high-mode-number non-uniformities [3][4][5][6][7][8].…”

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confidence: 99%

“…The high-Z plasma from the wall blow-off [usually gold (Au) or uranium], which causes motion of the laser absorption region and alters the spatial distributions of xray energy sources and sinks, has been shown to cause low-mode-number implosion asymmetries [3][4][5][6][7][8]. The blow-off quickly fills the interior of an initially empty (optically thin) hohlraum, leading to early on-axis plasma stagnation [3][4][5][6][7][8].…”

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