V Self Focusing of Laser Beams in Plasmas and Semiconductors

Sodha, M. S.; Ghatak, Ajoy; Tripathi, V. K.

doi:10.1016/s0079-6638(08)70021-0

Cited by 500 publications

(425 citation statements)

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“…The knee appearing in figure 7 is evidently due to a threshold-like phenomenon resulting from the possible nonlinear interactions such as self-focusing of the laser beam within the plasma medium. The Debye length, which is the characteristic screening length of the plasma, is given by [26,27,31] (4) where k, is the Boltzmann constant, To the equilibrium plasma temperature (-lo5 K), N the equilibrium concentration (-loL2 ~m -~) and e the electron charge.…”

Section: Resultsmentioning

confidence: 99%

Spatial and temporal analysis of laser induced plasma from a polymer sample

Padmaja

Kumar

Radhakrishnan

et al. 1993

J. Phys. D: Appl. Phys.

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Abstract. Spatial and temporal analyses of tne spectra of the aser induced plasma from a polytetrafluroethyene (PTFE) target ootaineo with the 1.06pm radiation from a 0-swltched Nd:YAG laser have been carried OLI. Tne spatia ly resolved spectra of ihe p asma emission show that molewlar bands 01 C1 (Swan bands) and CN are very intense in the outer regions of the plasma, wnereas hlgher ionized states 01 carbon are predominant n tne core region of the pasma emission. The viorational temperatLre and population Oistr bution in the dinerent vibrational levels have been stLdied as a function of laser energy. From the time reso.vea studies, it h a s been ObSeNed that there exist 1a.r y .arge time oelays for the onset of emission from a I the species in the outer region of the plasma. Also, the molecu ar bands in each region exhios much larger time delays in comparison to the ionic lines in the plasma.

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Section: Resultsmentioning

confidence: 99%

Spatial and temporal analysis of laser induced plasma from a polymer sample

Padmaja

Kumar

Radhakrishnan

et al. 1993

J. Phys. D: Appl. Phys.

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“…Nonlinear interactions of waves in plasmas also give rise to several self-action effects, i.e. shifts of wave parameters, wave precession, filamentation, modulational instabilities (Sodha et al 1976;Chakraborty et al 1983;Shukla et al 1986). In fact, shifts of refractive indices (i.e.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Shifts of Refractive Indices from Obliquely Propagating Waves in a Magnetised Plasma in the Presence of Coriolis Rotation

Kashyapi¹,

Paul²,

Chakraborty³

1992

Aust. J. Phys.

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This paper provides an expression for the nonlinear shifts of refractive indices from obliquely propagating waves in a cold, homogeneous, magnetised rotating plasma in the presence of a Coriolis force. The effects of gyrofrequency, rotational frequency, and the amplitude of the waves on the nonlinear shifts of refractive indices are discussed. It is found that these parameters play a dominant role in the nonlinear shifts of refractive indices and the results are more general than those of earlier workers.

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“…The self-focusing phenomenon of a laser beam in a nonlinear medium became a special interest to many because of its influence on all other nonlinear phenomena 9 Self-focusing phenomena within plasmas have generated a great deal of attention on account of their applicability to controlled thermonuclear fusion. Some have contemplated using laser beams to heat the plasma contained within reactors, since by doing so, one might relax the overall input power required in heating the reactors.…”

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“…The collisional heating of the plasma is also applicable to the heating of the ionosphere by a ground based HF transmitter, and has been of much interest in space communications and ionospheric diagnostics. 9 Several mechanisms have been proposed for self-focusing in plasmas. The first of these is a basic consequence of the ponderomotive forces exerted on the plasma by the light beam.…”

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confidence: 99%

“…It would be useful to visualize physically the phenomenon of self-focusing in a medium where the refractive index is an increasing function of the intensity EE" of the beam. 9 In another words, the radiation pressure from the intense beam tends to drive electrons out of the beam resulting in a higher index of refraction at the center of the beam. Thus, a sufficiently intense electromagnetic wave can create its own waveguide.…”

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confidence: 99%

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