Induced Compton Scattering and Nonlinear Propagation in Laser-Created Plasmas

Abstract

Phys. 42, 1378. 3~In the two-fluid model of superfluid helium the superfluid density is identified with the square of the order parameter (see for example, Bef. 21}.We have obtained some evidence of the induced scattering of an electromagnetic wave by Compton collisions, and of its nonlinear propagation in a plasma. The interpretation of the modified spectral profile of the interacting radiation is compatible with plasma parameters.

Twenty-two years of laser-matter work at Centre d'Etudes de Limeil-Valenton (CEL-V)

“…The first experimental evidence of this was obtained by analysing NUCLEAR FUSION, Vol.25, No.9 (I98S) the forward scattering of a 1.06 nm laser beam focused on a solid D 2 target at the level of 10 12 Wcm" 2 . An induced phenomenon was observed which propagated non-linearly, preserving polarization and showing a spectral shift towards longer wavelengths; these characteristics were interpreted according to the induced Compton scattering theory [12]. An exciting result was the observation of 1/2 co, 3/2 co and 2 o> harmonics, the occurrence and low-frequency broadening of which were ascribed to parametric excitation of waves [13].…”

Harmonic Generation and Parametric Excitation of Waves in a Laser-Created Plasma

“…It was partially described in another paper. 8 Spectral observations were made using a Czerny-Turner grating spectrometer with a mean dispersion of 8 A/mm in the first order. For recording in the visible range we used a multichan- neltron image amplifier (IA) fitted with an S 20 photocathode.…”

“…Therefore, the coefficient of the corresponding term in the right-hand side of (5) should also vanish in order to get a finite solution for (4). Associating (6) with the first element of the set (7) one should have W^itfcoo-W,), 2k(fco 0 -fft s ) = 2k 0 + k L , (8) and the condition on the coefficient gives A l =a 1 exp(y l t 1 ) + a 1 ' expi-y^J (9) with growth rate…”

Avalanche Photon Cooling by Induced Compton Scattering: Higher-Order Kompaneets Equation

“…ICS has been studied in the context of laser plasma interaction both theoretically [8][9][10] and experimentally [11][12][13][14]. Most of them studied the process with the two-fluid approximation, which accounts only for the linear regime of the instability.…”