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

Document Type

Article

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.