ATOMIC PROCESSES IN PLASMAS, Proceedings of the 16th International Conference on Atomic Processes in Plasmas
巻, 号, ページ
Volume 1161
pp. 254
出版年月
2009年8月
出版者
和文:
英文:
会議名称
和文:
The 16th International Conference on Atomic Processes in Plasmas
英文:
開催地
和文:
英文:
Monterey, California, USA, March, 22-26, 2009.
アブストラクト
In fast ignition research, the transport dynamics of fast electrons is one of critical issues. Fast electrons are generated through collective processes with an intense laser pulse, and become highly anisotropic. Isotropic cold bulk electrons form a return current to compensate fast electron current, and are heated via an ohmic process. To gain insight into the anisotropy of the velocity distribution of fast electrons, polarized x-ray spectroscopy has been proposed. At a laser intensity of about 10^17^ W/cm^2^, the polarization spectroscopy of Cl Heα radiation was carried out, and has been demonstrated a useful diagnostic tool [1,2]. A new time-dependent atomic population kinetics code has been developed for the study of polarized Cl Heα radiation. The calculation code predicts that the polarization arises only in low density region, and no polarization is found in such dense region as solid [3,4]. Additional x-ray polarization measurement was done at 10^17-18^ W/cm^2^ (~10 J in ~1 ps) from Alisé facility at CEA/CESTA. Chlorinated triple-layer targets were used. Polarization was measured as a function of the overcoat thickness of the target. The polarization is negative at the shallow region from the target surface, and becomes near zero at the higher laser intensity. At the lower laser intensity, the polarization varies from negative to positive, and finally zero along with the overcoat thickness. In the talk, comparison between the model predictions and the experimental results will be discussed.
[1] H. Nishimura, Plasma Phys. Control. Fusion 47, B823 (2005).
[2] Y. Inubushi, et al., JQSRT 99, 305 (2006); 101, 191 (2006); Phys. Rev. E 75, 026401 (2007).
[3] T. Kai, et al., Phys. Rev A 75, 012703 (2007),
[4] T. Kawamura, et al., Phys. Rev. Lett., 99, 115003 (2007).
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