Theory of transient self‐focusing of a CO2laser pulse in a cold dense plasma
作者:
A. Schmitt,
R. S. B. Ong,
期刊:
Journal of Applied Physics
(AIP Available online 1983)
卷期:
Volume 54,
issue 6
页码: 3003-3011
ISSN:0021-8979
年代: 1983
DOI:10.1063/1.332503
出版商: AIP
数据来源: AIP
摘要:
The self‐focusing of laser pulses in a plasma is theoretically investigated for the situation in which the refractive index change is not in equilibrium with the pulse. In particular, the analysis models a CO2laser–plasma interaction experiment in which the ponderomotive and thermal conduction dominated mechanisms of self‐focusing are dominant. The moment method and the Gaussian shape ansatz are used to describe the laser pulse propagation. Threshold powers are derived for the transient self‐focusing process, which reveals that self‐focusing can occur even for times much less than the characteristic dielectric relaxation time. Because of the behavior of the pulse heating, thermal conduction dominated self‐focusing is inherently a transient phenomenon without a true steady state limit. The governing equations are also numerically solved, revealing the existence of ion acoustic waves created by the action of moving focal spots. These transversely propagating waves may be responsible for breakup or filamentation of the laser pulse.
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