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Self-focusing and filamentation of laser beams in collisional plasmas with finite thermal conduction

Published online by Cambridge University Press:  13 March 2009

Ghanshyam  and
V. K. Tripathi
Ghanshyam
Affiliation:
Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110016, India
V. K. Tripathi
Affiliation:
Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110016, India
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Abstract

A Gaussian laser beam propagating through a plasma heats the electrons and creates a low-density duct via ambipolar diffusion. Thermal conduction plays an important role in temperature equilibrium when the electron mean free path λm is greater than the beam radius (λm ≥ ro). For λm ≫ ro thermal conduction suppresses any non-uniformities in electron temperature, and nonlinearity is dominated by the ponderomotive force. The plasma duct traps and focuses the laser radiation above a threshold power. As the beam size shrinks, thermal conduction becomes stronger, leading to periodic self-focusing of the beam. The laser beam is also susceptible to filamentation instability. The spatial growth rate is a monotonically increasing and saturating function of the incident intensity of the beam.

Type
Research Article
Information
Journal of Plasma Physics , Volume 49 , Issue 2 , April 1993 , pp. 243 - 253
Copyright
Copyright © Cambridge University Press 1993

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