Intense laser pulse amplification using Raman backscatter in plasma channels

Mardahl, P.; Lee, H. J.; Penn, G.; Wurtele, J. S.; Fisch, Nathaniel J.

doi:10.1016/s0375-9601(02)00194-9

Cited by 39 publications

(18 citation statements)

References 12 publications

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“…35 The counterpropagating very high-power wave geometry might also have some interesting spin-off applications. One possibility is for the purpose of accelerating relativistic particle beams through the plasma wave produced in the counterpropagating geometry.…”

Section: Variations and Spin-off Applicationsmentioning

confidence: 99%

Generation of ultrahigh intensity laser pulses

Fisch

Malkin

2003

Physics of Plasmas

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Mainly due to the method of chirped pulse amplification, laser intensities have grown remarkably during recent years. However, the attaining of very much higher powers is limited by the material properties of gratings. These limitations might be overcome through the use of plasma, which is an ideal medium for processing very high power and very high total energy. A plasma can be irradiated by a long pump laser pulse, carrying significant energy, which is then quickly depleted in the plasma by a short counterpropagating pulse. This counterpropagating wave effect has already been employed in Raman amplifiers using gases or plasmas at low laser power. Of particular interest here are the new effects which enter in high power regimes. These new effects can be employed so that one high-energy optical system can be used like a flashlamp in what amounts to pumping the plasma, and a second low-power optical system can be used to extract quickly the energy from the plasma and focus it precisely. The combined system can be very compact. Thus, focused intensities more than 10 25 W/cm 2 can be contemplated using existing optical elements. These intensities are several orders of magnitude higher than what is currently available through chirped pump amplifiers.

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Section: Variations and Spin-off Applicationsmentioning

confidence: 99%

Generation of ultrahigh intensity laser pulses

Fisch

Malkin

2003

Physics of Plasmas

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“…The numerical models employed by these studies, however, did not include the physics of wave-breaking or saturation. Some modeling with the particle-in-cell (PIC) code XOOPIC [12] has also been performed [13], in particular to investigate amplification in plasma channels [14], but there has been no systematic application of the fully kinetic model of the plasma provided by a PIC code to the problem of saturation of Raman amplification or the details of wave-breaking in amplification. Further, given that the pump beam in a Raman amplifier can be expected to heat the plasma to ∼ 100 eV by the time the seed pulse is injected into the plasma and also based on considerations of the stability of the pump beam to backscatter from thermal plasma noise [15], the effect of wave-breaking on amplification in a finite temperature plasma is of particular interest.…”

Section: Introductionmentioning

confidence: 99%

Particle-in-cell simulations of Raman laser amplification in preformed plasmas

Clark

Fisch²

2003

Physics of Plasmas

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Two critical issues in the amplification of laser pulses by backward Raman scattering in plasma slabs are the saturation mechanism of the amplification effect (which determines the maximum attainable output intensity of a Raman amplifier) and the optimal plasma density for amplification. Previous investigations [V. M. Malkin, et al. , Phys. Rev. Lett., 82(22):4448-4451, 1999] identified forward Raman scattering and modulational instabilities of the amplifying seed as the likely saturation mechanisms and lead to an estimated unfocused output intensities of 10 17 W/cm 2 . The optimal density for amplification is determined by the competing constraints of minimizing the plasma density so as to minimize the growth rate of the instabilities leading to saturation but also maintaining the plasma sufficiently dense that the driven Langmuir wave responsible for backscattering does not break prematurely. Here, particle-in-cell code simulations are presented which verify that saturation of backward Raman amplification does occur at intensities of ∼ 10 17 W/cm 2 by forward Raman scattering and modulational instabilities. The optimal density for amplification in a plasma with the representative temperature of Te = 200 eV is also shown in these simulations to be intermediate between the cold plasma wave-breaking density and the density limit found by assuming a water bag electron distribution function.

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“…4a) might be attractive, for instance, for SRB schemes with strong plasma wave localization. 19,20 It was shown that in a multimode regime, continuum modes of the plasma channel might contract the backscattered beam and increase the growth rate. 21 For our parameters of the channel (density at the axis n e0 ~ 1.2 ×10 19 cm -3 and the average depth of the channel ∆n e ~ 40%), the plasma density gradient exceeds the bandwidth of SRB: η = (δn er / n e0 )/(2γ/ω p0 ) ~ 20-50 for beams with a power density of about 10 14 W/cm 2 .…”

Section: Longitudinal Profilementioning

confidence: 99%

Formation of laser plasma channels in a stationary gas

et al. 2006

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The formation of plasma channels with nonuniformity of about ± 3.5% has been demonstrated. The channels had a density of 1.2×10 19 cm -3 with a radius of 15 µm and with length ≥ 2.5 mm. The channels were formed by 0.3 J, 100 ps laser pulses in a nonflowing gas, contained in a cylindrical chamber. The laser beam passed through the chamber along its axis via pinholes in the chamber walls. A plasma channel with an electron density on the order of 10 18 -10 19 cm -3 was formed in pure He, N 2 , Ar, and Xe. A uniform channel forms at proper time delays and in optimal pressure ranges, which depend on the sort of gas. The influence of the interaction of the laser beam with the gas leaking out of the chamber through the pinholes was found insignificant. However, the formation of an ablative plasma on the walls of the pinholes by the wings of the radial profile of the laser beam plays an important role in the plasma channel formation and its uniformity. A low current glow discharge initiated in the chamber slightly improves the uniformity of the plasma channel, while a high current arc discharge leads to the formation of overdense plasma near the front pinhole and further refraction of the laser beam. The obtained results show the feasibility of creating uniform plasma channels in non-flowing gas targets.

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Intense laser pulse amplification using Raman backscatter in plasma channels

Cited by 39 publications

References 12 publications

Generation of ultrahigh intensity laser pulses

Generation of ultrahigh intensity laser pulses

Particle-in-cell simulations of Raman laser amplification in preformed plasmas

Formation of laser plasma channels in a stationary gas

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