Demonstration of detuning and wavebreaking effects on Raman amplification efficiency in plasma

Yampolsky, Nikolai; Fisch, Nathaniel J.; Malkin, V. M.; Valeo, E. J.; Lindberg, Ryan; Wurtele, J. S.; Ren, Jun; Li, S.; Morozov, A.; Suckewer, S.

doi:10.1063/1.3023153

Cited by 54 publications

(36 citation statements)

References 37 publications

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“…Previous theoretical and computational works have focussed on the optimal pump amplitude for efficient amplification [2,5,11,12]. Although it is known that the highest efficiencies are achieved below the wavebreaking threshold, the necessarily low intensities would require large interaction volumes to scale to high power.…”

Section: Introductionmentioning

confidence: 99%

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Raman amplification in the coherent wave-breaking regime

Farmer¹,

Pukhov²

2015

Phys. Rev. E

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In regimes far beyond the wavebreaking threshold of Raman amplification, we show that significant amplifcation can occur after the onset of wavebreaking, before phase mixing destroys the coherent coupling between pump, probe and plasma wave. Amplification in this regime is therefore a transient effect, with the higher-efficiency "coherent wavebreaking" (CWB) regime accessed by using a short, intense probe. Parameter scans illustrate the marked difference in behaviour between below wavebreaking, in which the energy-transfer efficiency is high but total energy transfer is low, wavebreaking, in which efficiency is low, and CWB, in which moderate efficiencies allow the highest total energy transfer.

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Section: Introductionmentioning

confidence: 99%

“…18 W cm −2 [3], leading to strong damping [4], which will limit the coupling between pump and probe [5].…”

Section: Introductionmentioning

confidence: 99%

Raman amplification in the coherent wave-breaking regime

Farmer¹,

Pukhov²

2015

Phys. Rev. E

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“…As predicted, there are no secondary trailing peaks. Although, suppression of these peaks is also possible when the pump exceeds the threshold wavebreaking intensity [35][36][37][38][39] , here this was only true for the first 20% of the propagation. We therefore attribute the suppression to the divergence of the pulse, rather than premature breaking of the plasma wave.…”

Section: Resultsmentioning

confidence: 96%

Advantages to a diverging Raman amplifier

Sadler¹,

Silva²,

Fonseca³

et al. 2018

Commun Phys

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The plasma Raman instability can efficiently compress a nanosecond long high-power laser pulse to sub-picosecond duration. Although, many authors envisaged a converging beam geometry for Raman amplification, here we propose the exact opposite geometry; the amplification should start at the intense focus of the seed. We generalise the coupled laser envelope equations to include this non-collimated case. The new geometry completely eradicates the usual trailing secondary peaks of the output pulse, which typically lower the efficiency by half. It also reduces, by orders of magnitude, the initial seed pulse energy required for efficient operation. As in the collimated case, the evolution is self similar, although the temporal pulse envelope is different. A two-dimensional particle-in-cell simulation demonstrates efficient amplification of a diverging seed with only 0.3 mJ energy. The pulse has no secondary peaks and almost constant intensity as it amplifies and diverges.

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“…The major physical processes that may affect BRA include the amplified pulse filamentation and detuning due to the relativistic electron nonlinearity 1,4,12-16 , parasitic Raman scattering of the pump and amplified pulses by plasma noise 1, 3,4,[17][18][19] , generation of superluminous precursors of the amplified pulse 20 , pulse scattering by plasma density inhomogeneities 21 , pulse depletion and plasma heating through inverse bremsstrahlung [22][23][24][25] , the resonant Langmuir wave Landau damping 22,24,[26][27][28][29][30][31] or breaking 1, 3,4,32,33 , and other processes (see for example [34][35][36][37]). Most of these deleterious processes can be mitigated by appropriate preparation of laser pulses and plasmas, choosing parameter ranges and selective detuning of the Raman resonance.…”

Section: Introductionmentioning

confidence: 99%

Exceeding the leading spike intensity and fluence limits in backward Raman amplifiers

2014

Self Cite

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The leading amplified spike in backward Raman amplifiers can reach nearly relativistic intensities before the saturation by the relativistic electron nonlinearity. The saturation sets an upper limit to the largest achievable leading spike intensity. It is shown here that this limit can be substantially exceeded by the initially subdominant spikes, which surprisingly outgrow the leading spike after its nonlinear saturation. Furthermore, an initially negligible group velocity dispersion of the amplified pulse in strongly undercritical plasma appears to be capable of delaying the longitudinal filamentation instability in the nonlinear saturation regime. This enables further amplification of the pulse to even larger output fluences.

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Demonstration of detuning and wavebreaking effects on Raman amplification efficiency in plasma

Cited by 54 publications

References 37 publications

Raman amplification in the coherent wave-breaking regime

Raman amplification in the coherent wave-breaking regime

Advantages to a diverging Raman amplifier

Exceeding the leading spike intensity and fluence limits in backward Raman amplifiers

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