Nonlinear Frequency Shift of an Electron Plasma Wave

Morales, G. J.; O’Neil, T. M.

doi:10.1103/physrevlett.28.417

Cited by 259 publications

(207 citation statements)

References 5 publications

Supporting

Mentioning

187

Contrasting

Unclassified

Order By: Relevance

“…[14] and [11] suggest that kinetic effects might dominate fluid effects even for large amplitudes of LW if kλ D > 0.3. Though the trapped electron frequency shift, perturbatively, varies as |E| 1/2 [6,9,10], and therefore cannot lead to LW collapse [13,45,46], 3D PIC simulation results [18] have been interpreted as showing that the trapped electron LW filamentation instability can saturate [19] stimulated Raman back-scatter (SRS) [21] by reducing the LWs coherence.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Langmuir wave filamentation in the kinetic regime. I. Filamentation instability of Bernstein-Greene-Kruskal modes in multidimensional Vlasov simulations

2017

View full text Add to dashboard Cite

A nonlinear Langmuir wave in the kinetic regime kλD 0.2 may have a filamentation instability, where k is the wavenumber and λD is the Debye length. The nonlinear stage of that instability develops into the filamentation of Langmuir waves which in turn leads to the saturation of the stimulated Raman scattering in laser-plasma interaction experiments. Here we study the linear stage of the filamentation instability of the particular family [1] of Bernstein-Greene-Kruskal (BGK) modes [2] that is a bifurcation of the linear Langmuir wave. Performing direct 2+2D Vlasov-Poisson simulations of collisionless plasma we find the growth rates of oblique modes of the electric field as a function of BGK's amplitude, wavenumber and the angle of the oblique mode's wavevector relative to the BGK's wavevector. Simulation results are compared to theoretical predictions.

show abstract

Section: Conclusion and Discussionmentioning

confidence: 99%

“…[8], the transition from the fluid to the "kinetic" regime occurs at kλ D ∼ 0.2 when trapped electron effects cannot be ignored. The LW frequency shift due to electron trapping, ∆ω trapped , perturbatively varies as ∆ω trapped ∝ |E| 1/2 [1,6,[8][9][10] with possible higher order corrections as discussed in Ref. [11].…”

Section: Introductionmentioning

confidence: 99%

Langmuir wave filamentation in the kinetic regime. I. Filamentation instability of Bernstein-Greene-Kruskal modes in multidimensional Vlasov simulations

2017

View full text Add to dashboard Cite

show abstract

“…Early in time it occurs at the seed frequency ω 1s but upshifts once SRBS becomes strongly enhanced around 3 ps. This results from the trapping-induced EPW frequency downshift [15]. Scattered light between the SRBS and pump frequencies is observed shortly after the upshift.…”

Section: A Reflected Lightmentioning

confidence: 99%

“…The above criterion treats longitudinal endloss as the only de-trapping mechanism, since we have not included transverse sideloss (e.g., via the Krook operator) in our runs. Morales and O'Neil calculate the timedependent damping rate and frequency of an undriven EPW as an initial value problem [14,15]. That is, the damping and frequency vary with the number of bounce orbits the trapped particles have experienced, defined below as N B .…”

Section: Intensity Scaling Of Srbs For Trident Conditionsmentioning

confidence: 99%

Kinetic enhancement of Raman backscatter, and electron acoustic Thomson scatter

et al. 2007

View full text Add to dashboard Cite

1-D Eulerian Vlasov-Maxwell simulations are presented which show kinetic enhancement of stimulated Raman backscatter (SRBS) due to electron trapping in regimes of heavy linear Landau damping. The conventional Raman Langmuir wave is transformed into a set of beam acoustic modes [L. Yin et al., Phys. Rev. E 73, 025401 (2006)]. For the first time, a low phase velocity electron acoustic wave (EAW) is seen developing from the self-consistent Raman physics. Backscatter of the pump laser off the EAW fluctuations is reported and referred to as electron acoustic Thomson scatter. This light is similar in wavelength to, although much lower in amplitude than, the reflected light between the pump and SRBS wavelengths observed in single hot spot experiments, and previously interpreted as stimulated electron acoustic scatter [D. S. Montgomery et al., Phys. Rev. Lett. 87, 155001 (2001)]. The EAW observed in our simulations is strongest well below the phase-matched frequency for electron acoustic scatter, and therefore the EAW is not produced by it. The beating of different beam acoustic modes is proposed as the EAW excitation mechanism, and is called beam acoustic decay. Supporting evidence for this process, including bispectral analysis, is presented. The linear electrostatic modes, found by projecting the numerical distribution function onto a GaussHermite basis, include beam acoustic modes (some of which are unstable even without parametric coupling to light waves) and a strongly-damped EAW similar to the observed one. This linear EAW results from non-Maxwellian features in the electron distribution, rather than nonlinearity due to electron trapping.

show abstract

“…The theoretically achievable value of |A 3 | max is less than the unity, which is called the wave breaking. Before |A 3 | reaches the wave breaking, various saturation mechanisms come into play, including the frequency detuning and the soliton formation [32,33]. These mechanisms make the linear theory presented here become insufficient.…”

mentioning

confidence: 99%

Backward Raman compression of x-rays in metals and warm dense matters

Son

Moon

2010

Physics of Plasmas

View full text Add to dashboard Cite

Experimentally observed decay rate of the long wavelength Langmuir wave in metals and dense plasmas is orders of magnitude larger than the prediction of the prevalent Landau damping theory. The discrepancy is explored, and the existence of a regime where the forward Raman scattering is stable and the backward Raman scattering is unstable is examined. The amplification of an x-ray pulse in this regime, via the backward Raman compression, is computationally demonstrated, and the optimal pulse duration and intensity is estimated.PACS numbers: 52.38.-r, 52.59. Ye, 42.60.Jf Coherent intense x-rays would enable various potential applications [1,2], however, it is very difficult to compress an x-ray pulse, or even in the UV regime. Some progress has been made in this direction, based on the recent advances in the areas of free electron laser [3] and the inertial confinement fusion [4]. It is shown that the backward Raman scattering (BRS) [5,6], where two light pulses and a Langmuir wave interact one another to exchange the energy, is one promising approach to create an ultra short light pulse (down to a few attoseconds [7,8]); a pulse gets compressed and intensified via this laser-plasma interaction. The BRS is successfully used to create intense pulses of the visible light frequencies [9,10]. It is natural to consider the same technique for the x-ray compression [7,8]. However, some physical processes in the regime where x-rays might be compressible are considerably different from those in the visible light regime. There are new physical processes to be considered, such as the Fermi degeneracy and the electron quantum diffraction [11][12][13][14], to mention a few.We consider one key aspect for the BRS in the x-ray compression regime, i.e., the damping of the Langmuir wave. In an ideal plasma, the decay rate of the Langmuir wave increases rapidly as the wavelength decreases. It poses a concern for the BRS, as the plasmon from the forward Raman scattering (FRS), having a lower wave vector than the BRS, depletes the pump. There have been various attempts to suppress the FRS in the visible light regime [15]. The situation is different in metals and the warm dense matters that we consider for the x-ray compression. The interaction of electrons via the inter-band transition (the Umklapp process) [16][17][18][19][20][21][22] becomes the dominant plasmon decay process, in contrast to the Landau damping in an ideal plasma. As a consequence, the decay rate of the long wavelength plasmon * Electronic address: seunghyeonson@gmail.com † Electronic address: sku@cims.nyu.edu ‡ Current address: Citigroup, 388 Greenwich St. New York, NY 10013 is much higher than the prediction of the prevalent dielectric function theory. In this paper, we show that a parameter regime where the BRS is unstable and the FRS is stable does exist in metals and warm dense matters, as the plasmon from the FRS strongly decays. Here, we consider metals in room temperature, and show that an x-ray pulse can be compressed in this regime. We estimate an optima...

show abstract

Nonlinear Frequency Shift of an Electron Plasma Wave

Cited by 259 publications

References 5 publications

Langmuir wave filamentation in the kinetic regime. I. Filamentation instability of Bernstein-Greene-Kruskal modes in multidimensional Vlasov simulations

Langmuir wave filamentation in the kinetic regime. I. Filamentation instability of Bernstein-Greene-Kruskal modes in multidimensional Vlasov simulations

Kinetic enhancement of Raman backscatter, and electron acoustic Thomson scatter

Backward Raman compression of x-rays in metals and warm dense matters

Contact Info

Product

Resources

About