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Proceedings Paper

Structure and intensity of x-ray radiation in a laser plasma-wall interaction
Author(s): Alexander P. Shevelko; Larry V. Knight; Justin Peatross; Quan Wang
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Paper Abstract

Intense soft x-ray radiation is observed when a high temperature laser produced plasma collides with a solid surface (wall). The laser plasma is produced by Nd:YAG laser radiation (0.53 micrometers ; 200 mJ; 3 ns; 5x1012 w/cm2 focused onto a Mg target. The wall is placed in the path of the plasma expansion. Two experimental techniques are used. 1) One-dimensional x-ray images of the plasma-wall gap formed by a slit are observed using an absolutely calibrated CCD linear array. 2) X-ray spectra of [H]- and [He]-like Mg ions are recorded using a crystal focusing x-ray von Hamos spectrometer. At a measured electron temperature of Te equals 195 eV, emission of [He]-like ions Mg XI gives the main contribution to the observed x-ray intensity. The spatial structure and the intensity of the radiation are studied at various laser plasma-wall distances (r0 equals 0.3 - 3.0 mm). Intense radiation near the wall is caused by an electron density jump in a shockwave formed in front of the wall. At small wall distances r0<<v(tau) (v is the expansion velocity, tau is the laser pulse duration) the radiation is caused by excitation processes, and at distances r0<0.3 mm the near wall intensity exceeds the emission from the laser plasma itself. At distances r0$GTR$GTRv(tau) the radiation causes recombination processes. These results are important for developing collision and recombination schemes for x-ray lasers in colliding plasmas.

Paper Details

Date Published: 12 December 2001
PDF: 8 pages
Proc. SPIE 4505, Soft X-Ray Lasers and Applications IV, (12 December 2001); doi: 10.1117/12.450588
Show Author Affiliations
Alexander P. Shevelko, P.N. Lebedev Physical Institute (Russia)
Larry V. Knight, Brigham Young Univ. (United States)
Justin Peatross, Brigham Young Univ. (United States)
Quan Wang, Brigham Young Univ. (United States)

Published in SPIE Proceedings Vol. 4505:
Soft X-Ray Lasers and Applications IV
Ernst E. Fill; Jorge J. G. Rocca, Editor(s)

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