Polarized He{sub a}lpha Radiation by Anisotropic Fast Electron Transport in Ultra-Intense Laser Produced Plasmas

Journal Article · Thu Sep 10 00:00:00 EDT 2009 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3241198· OSTI ID:21344621

Kawamura, T ^[1]; Kai, T; Nishimura, H; Inubushi, Y; Okano, Y; Nagatomo, H; Fujioka, S; Nakamura, T; Johzaki, T; Mima, K ^[2]; Koike, F ^[3]; Nakazaki, S ^[4]; Batani, D; Morace, A; Redaelli, R ^[5]; Fourment, C; Santos, J ^[6]; Malka, G ^[7]; Boscheron, A ^[8]; Casner, A ^[9]

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1. Department of Energy Sciences, Tokyo Institute of Technology (Japan)
2. Institute of Laser Engineering, Osaka University (Japan)
3. School of Medicine, Kitasato University (Japan)
4. Department of Applied Physics, University of Miyazaki (Japan)
5. University of Milano, Bicocca (Italy)
6. CELIA Universite de Bordeaux 1/CNRS/CEA, Talence (France)
7. CENBG Universite de Bordeaux 1/CNRS-IN2P3, Gradignan (France)
8. CEA/CESTA Le BARP (France)
9. CEA-DAM Ile de France, Bruyres-le-Chtel (France)

In fast ignition research, the transport dynamics of fast electrons is one of the critical issues. Fast electrons generated by an intense laser pulse show a highly anisotropic velocity distribution. To gain insight into the anisotropy of the velocity distribution of fast electrons, polarized x-ray spectroscopy has been proposed. The polarization spectroscopy of Cl He{sub a}lpha radiation was experimentally demonstrated at 10{sup 17} W/cm{sup 2}(approx100 mJ in 130 fs), and a new time-dependent atomic population kinetics code was also developed. It predicts that the high polarization arises only in a low-density region of the target plasma. Additional x-ray polarization measurements were done at 10{sup 1717-18} W/cm{sup 2}(approx10 J in approx1 ps). Polarization was measured as a function of the overcoat thickness of a target. The polarization is negative in the shallow region near the target surface, and becomes near zero at the laser intensity of approx10{sup 18} W/cm{sup 2}. At approx10{sup 17} W/cm{sup 2}, the polarization varies from negative to positive, and finally zero along with an increase in the overcoat thickness.

• OSTI ID: 21344621
• Journal Information: AIP Conference Proceedings, Vol. 1161, Issue 1; Conference: 16. international conference on atomic processes in plasmas, Monterey, CA (United States), 22-26 Mar 2009; Other Information: DOI: 10.1063/1.3241198; (c) 2009 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANISOTROPY
CHARGED-PARTICLE TRANSPORT
COMPUTERIZED SIMULATION
ELECTRONS
GAIN
LASER TARGETS
LASER-PRODUCED PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA SIMULATION
POLARIZATION
PULSED IRRADIATION
THERMONUCLEAR IGNITION
X-RAY SPECTROSCOPY
AMPLIFICATION
ELEMENTARY PARTICLES
FERMIONS
IRRADIATION
LEPTONS
PLASMA
RADIATION TRANSPORT
SIMULATION
SPECTROSCOPY
TARGETS