The evolution of ultra-intense, short-pulse lasers in underdense plasmas

Decker, C. D.; Mori, W. B.; Tzeng, K. C.; Katsouleas, T.

doi:10.1063/1.872001

Cited by 207 publications

(215 citation statements)

References 33 publications

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“…Equation (10) is the central result of this paper, and it generalizes the seminal result of Decker et al [15] for pump fields with arbitrary statistics. It can be interpreted as the statistical average of 1…”

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confidence: 70%

“…In the limit of σ 1,2 → 0, the standard monochromatic result, valid for all intensities, is obtained [15], with Γ RFS ∝ a −1 0 for a 0 ≫ 1. The effect of the bandwidth on four wave processes, such as RFS, predicted by Eq.…”

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confidence: 99%

“…This restriction is introduced only because of the perturbation technique we are employing; the formalism described here is valid for any field dependence. When the uniform plasma is irradiated by the electromagnetic field, described by the normalized vector potential a = a p +ã, the normalized electron density n e = 1 +ñ satisfies [15]:…”

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confidence: 99%

“…Usually, the driving term on the right hand side of Eq. (1) is described with the standard approach based on the wave equation for the vector potential [4,15]. However, this technique does not allow for the study of "white" light parametric instabilities.…”

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confidence: 99%

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White-Light Parametric Instabilities in Plasmas

Santos¹,

Silva²,

Bingham

2007

Phys. Rev. Lett.

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Parametric instabilities driven by partially coherent radiation in plasmas are described by a generalized statistical Wigner-Moyal set of equations, formally equivalent to the full wave equation, coupled to the plasma fluid equations. A generalized dispersion relation for Stimulated Raman Scattering driven by a partially coherent pump field is derived, revealing a growth rate dependence, with the coherence width σ of the radiation field, scaling with 1/σ for backscattering (three-wave process), and with 1/σ 1/2 for direct forward scattering (four-wave process). Our results demonstrate the possibility to control the growth rates of these instabilities by properly using broadband pump radiation fields.Parametric instabilities are pervasive in many fields of science, associated with the onset of nonlinear and collective effects such as solitons, vortices, self-organization, and spontaneous ordering. Recent developments in light sources and laser technology continue to reveal novel features of the parametric instabilities, for instance in nonlinear optics, with the recent experimental discovery of white light solitons [1], or in plasma physics, in the realm of relativistic nonlinear optics [2]. The standard theoretical approach to study parametric instabilities is based on a coherent wave description which is clearly limited because, in most systems, waves are only partially coherent, with incoherence either inherently induced by fluctuations, or induced by external passive systems (e.g. random phase plates in inertial confinement fusion (ICF)). Recent theoretical work in nonlinear optics, triggered by the work of Segev and co-workers [1], led to the development of techniques capable of describing the propagation and the modulation instability of partially coherent/incoherent "white" light in nonlinear media [3]. The critical underlying assumption of all these models is the paraxial wave approximation, valid in transparent media for radiation beams not tightly focused, which reduces the problem of electromagnetic wave propagation in dispersive (and diffractive) nonlinear media to the search of a forward propagating solution, formally described by the nonlinear Schrödinger equation. While in nonlinear optics, and for the conditions studied so far, such approximation is clearly valid, in plasma physics it is not. The instabilities associated with the partially reflected backscattered radiation [4] are critical in many laser-plasma and astrophysical scenarios [5], and the paraxial approximation has limited applicability even in the description of forward scattering instabilities driven by ultra intense lasers in underdense/transparent plasmas [6].Inclusion of bandwidth/incoherence effects in laser driven parametric instabilities in plasmas and in three-wave processes is a long-standing problem [7,8], because incoherent pumps can decrease the growth of the laser driven instabilities in ICF, Fast Ignition, or novel laser amplification schemes [9]. The difficulty resides in the lack of an appropriate theoretical framework...

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White-Light Parametric Instabilities in Plasmas

Santos¹,

Silva²,

Bingham

2007

Phys. Rev. Lett.

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“…As illustrated by the plasma emission lines in Figure 6.2, which correspond to the same experiment shown in the interferogram, nitrogen is present in the injector stage only. As shown in [38] and local pump depletion [31], respectively, experienced by portions of the incident laser pulse as it produces the plasma and excites the wake within the injector stage. In the longer, two-stage case, the extent of the red-shifting approximately doubles compared with the injector-only data, indicating that, in addition to the laser pulse continuing to self-guide across the interface between the two stages, the wake is also driven over the extended distance.…”

Section: Two-stage Lwfa Experimentsmentioning

confidence: 99%

Energy Spread Reduction of Electron Beams Produced via Laser Wake

Pollock

2012

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Simulation of a chirped femtosecond relativistic laser pulse interaction with underdense plasma by using a hydrodynamic approach

Zhu

et al. 2019

Contributions to Plasma Physics

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A chirped laser pulse indicates that the laser frequency changes over the duration of the pulse: a positively (negatively) chirped pulse implies that the laser frequency increases (decreases) with time. In this paper, we use a simplified, fully relativistic hydrodynamic approach to simulate the influence of chirp on the propagation of a femtosecond relativistic laser pulse in underdense plasma. Based on this simplified cold-fluid model, the influence of chirp on the main dynamics of the laser pulse, such as self-steepening, red-shift in the leading edge, variation of the frequency chirp, and the generated wakefields can be studied self-consistently. The simulation results show that a pulse with a positive chirp results in a larger increment in the intensity parameter a 0 when propagating a certain distance into an underdense plasma compared with an un-chirped and a negatively chirped pulse, which is largely because of a much greater forward shift of the peak amplitude and more severe pulse self-steepening effect due to the frequency red-shift at the leading edge when exciting a plasma wave. The ponderomotive force, which relates to the first-order differential of the laser pulse intensity envelope, is expected to be stronger for a positively chirped pulse because of its steeper leading edge and larger intensity parameter a 0 .As a result, the wakefield driven by the positively chirped laser pulse is more intense than that driven by an un-chirped and a negatively chirped laser pulse, which is confirmed by our self-consistent hydrodynamic simulation. K E Y W O R D Schirp, femtosecond relativistic laser, plasma, wakefield INTRODUCTIONUsing the chirped pulse amplification (CPA) technique, ultrashort-pulse laser sources with durations on the femtosecond time scale can produce multi-terawatt and even petawatt power. [1][2][3] These laser pulses can be focused to intensities well above 10 18 W/cm 2 , [4] from which an electron will acquire a quiver velocity approaching the speed of light; that is, the electron motion in the laser fields becomes highly relativistic and non-linear. Thus, these laser pulses are called relativistic femtosecond laser pulses and have great applications in high energy density science, such as energetic electron acceleration, [5] ion acceleration, [6] attosecond pulses generation, [7,8] positron beams for laboratory astrophysics, [9] and so on. These applications require long laser

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The evolution of ultra-intense, short-pulse lasers in underdense plasmas

Cited by 207 publications

References 33 publications

White-Light Parametric Instabilities in Plasmas

White-Light Parametric Instabilities in Plasmas

Energy Spread Reduction of Electron Beams Produced via Laser Wake

Simulation of a chirped femtosecond relativistic laser pulse interaction with underdense plasma by using a hydrodynamic approach

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