Electromagnetic eigenmodes of collisional and collisionless plasmas and their stability to stimulated Brillouin scattering

Journal Article · Thu Feb 15 04:00:00 EST 2007 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2436735· OSTI ID:20974820

Pathak, Vishwa Bandhu; Tripathi, V K ^[1]

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1. Physics Department, Indian Institute of Technology, New Delhi 110016 (India)

Nonlinear electromagnetic eigenmodes of collisional and collisionless plasmas, when the temporal extent of the modes is longer than the ambipolar diffusion time, have been investigated. The nonlinearity in a collisionless plasma arises through ponderomotive force, whereas in collisional plasmas Ohmic nonlinearity prevails. The mode structure in both cases, representing a balance between the nonlinearity-induced self-convergence and diffraction-induced divergence, closely resembles Gaussian form. The spot size of the mode decreases with the increasing axial amplitude of the laser, attains a minimum, and then rises very gradually. The modes are susceptible to stimulated Brillouin backscattering. The growth rate of the Brillouin process initially increases with mode amplitude, attains a maximum, and then decreases. The reduction in the growth rate is caused by strong electron evacuation from the axial region by the ponderomotive force and thermal pressure gradient force created by nonuniform Ohmic heating.

• OSTI ID: 20974820
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 14; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AMBIPOLAR DIFFUSION
AMPLITUDES
BACKSCATTERING
BRILLOUIN EFFECT
COLLISIONAL PLASMA
COLLISIONLESS PLASMA
DIFFRACTION
ELECTRONS
LIGHT TRANSMISSION
NONLINEAR PROBLEMS
PLASMA HEATING
PLASMA INSTABILITY
PLASMA PRESSURE
PONDEROMOTIVE FORCE
PRESSURE GRADIENTS
STABILITY