Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves

Abstract

A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically-intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a non-relativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined, and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for non-relativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.

On the structure of relativistic hydrodynamics for hot plasmas

“…The fluid equations can be determined from the Vlasov-Maxwell equations, in the mean field approximation (see for instance [26]). Our model can be derived from the kinetic model as well.…”

Positron Acceleration in an Elongated Bubble Regime

“…Accordingly, in the ELBA setup, we found that the peak density of the electron filament formed behind the bubble increases with the resolution if a cold plasma is used. However, in a warm plasma, the catastrophic density compression is prevented by the thermal pressure [40][41][42]. It is found that the maximum density compression in the 1D warm plasma is [41]: n max /n 0 = (3θ) −1 + 1/2, where θ = k B T e /mc 2 and k B stands for the Boltzmann constant, making the width of density spike ∝ T .…”

On the Relativistic Harmonic Oscillator

“…Over the years, the study of relativistic oscillations has progressed in several avenues including the study of the Dirac oscillator theoretically [1][2][3][4] and experimentally [5], and the quantization of the relativistic harmonic oscillator [6][7][8][9][10][11]. Oscillations in the weak-relativistic limit have been of interest in Plasma Physics [12][13][14][15][16][17][18][19][20][21][22][23][24]. Results have been attained by either generating numerical solutions, or by expansions in powers of β 2 (β = (Max| |)/c) in the weak-relativistic limit [25][26][27][28][29][30][31][32][33][34][35].…”