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Effect of Self-focussed Laser Beam on Second Harmonic Generation in Cold Collisionless Plasma
Keshav Walia and Jasmeen Kaur

The present paper investigates the effect of self-focused laser beam on second harmonic generation in cold collisionless plasma by taking in to account ponderomotive nonlinearity. Due to presence of gaussian beam, there is redistribution of carriers from high field region to low field region by ponderomotive force, as a result of which a transverse density gradient is produced in the plasma. This transverse density gradient in turn generates an electron plasma wave at pump wave frequency. The electron plasma wave so generated interacts with the pump beam to produce second harmonics. The differential equation governing the evolution of spot size of laser beam has been derived by following Wentzel Kramers Brillouin(W.K.B) approximation and paraxial theory approach and has been solved numerically to investigate the effect of laser intensity, plasma density, laser spot size and plasma temperature on self-focusing of the laser beam and second harmonic yield.

Keywords: Self-focusing, Second harmonic Yield, Cold Collisionless Plasma, Ponderomotive force, Plasma density, Plasma temperature

PACS: 52.38.Hb, 52.35.Mw., 52.38.Dx

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