Session NP8: Poster Session V: MHD and Waves; Inertial Confinement Fusion II and HEDP Diagnostics; C-Mod Tokamak; ITER and Magnetic Fusion Development

9:30 AM–9:30 AM, Wednesday, November 14, 2007
Rosen Centre Hotel Room: Grand Ballroom, 9:30am - 12:30pm


Abstract ID: BAPS.2007.DPP.NP8.59

Abstract: NP8.00059 : Supersonic Heat Wave Propagation in Laser-Produced Underdense Plasmas

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Authors:

  K.B. Fournier
    (LLNL, Livermore, CA)

  M. Tanabe
    (ILE, Osaka University, Japan)

  H. Nishimura
    (ILE, Osaka University, Japan)

  S. Fujioka
    (ILE, Osaka University, Japan)

  K. Nagai
    (ILE, Osaka University, Japan)

  A. Iwamae
    (Kyoto University, Kyoto, Japan)

  N. Ohnishi
    (Tohoku University, Sendai, Japan)

  F. Girard
    (CEA, Bruy$\grave{e}$res le Ch$\hat{a}$tel, France)

  M. Primout
    (CEA, Bruy$\grave{e}$res le Ch$\hat{a}$tel, France)

  B. Villette
    (CEA, Bruy$\grave{e}$res le Ch$\hat{a}$tel, France)

  D. Babnneuau
    (CEA, Bruy$\grave{e}$res le Ch$\hat{a}$tel, France)

  S. Moon
    (LLNL, Livermore, CA)

  S.B. Hansen
    (LLNL, Livermore, CA)

  M. Tobin
    (LLNL, Livermore, CA)

  K. Mima
    (ILE, Osaka University, Japan)

Intense, multi-keV X-ray sources are required for radiographic applications in laboratory astrophysics and ICF. Low-density targets are favorable for efficient laser-to-X-ray conversion because supersonic energy deposition leads to volumetric heating with low hydrodynamic losses. We report on recent X-ray generation experiments at the GEKKO XII laser. Ti-doped SiO$_2$ aerogel-filled (3.3 mg/cm$^3$, 3-6 atom\% Ti) Be or CH cylinders were irradiated with nine laser beams with a total of 1 kJ energy in a 2.5~ns square pulse, at 351~nm wavelength. Laser irradiance at the entrance of cylinder was 1.4${\times}$10$^{14}$ W/cm$^2$. The observed heat wave clearly shows two different phases in terms of propagation velocities. The measured heat-front propagation velocity was 1.4$\times$10$^8$ cm/s, which is a Mach number of 10 for the given conditions. Electron temperature in the heated target was derived from time-resolved X-ray spectra. By changing observation points, electron temperature profiles of the heat wave along the cylinder axis were obtained at different times.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.DPP.NP8.59