Pressure Ionization and Line Merging in Strongly Coupled Plasmas Produced by 100-fs Laser Pulses

Authors

M. Nantel, University of Michigan, Ann Arbor
G. Ma, University of Michigan, Ann Arbor
S. Gu, University of Michigan, Ann Arbor
C.Y. Côté, University of Michigan, Ann Arbor
J. Itatani, University of Michigan, Ann Arbor
Donald Umstadter, University of Nebraska-LincolnFollow

Date of this Version

5-18-1998

Comments

Published by American Physical Society. Physical Review Letters, 80, 4442 (1998). http://prl.aps.org. Copyright © 1998 American Physical Society. Permission to use.

Abstract

Time- and space-resolved extreme ultraviolet spectra of carbon plasmas, created with 100-fs laser pulses, are obtained with the novel technique of picosecond jitter-free streak-camera averaging. Spectroscopic diagnostics indicate electron densities and temperatures evolving from 10²³ to 10²¹ cm^-3 and 80 to 50 eV, respectively, implying less than one particle in a Debye sphere at early times. The emission reveals conditions of extreme pressure ionization and line merging. Comparisons of the experimental spectra with numerical simulations validate the use of the Inglis-Teller limit for line merging, and confirm that pressure ionization models based on the Debye-Huckel potential are inapplicable in such strongly coupled plasmas.