Kinetic modeling of intense, short laser pulses propagating in tenuous plasmas

Abstract

Fast time averaged equations are derived for the motion of particles and the generation of electromagnetic wake fields under the action of the ponderomotive potential of an ultraintense laser pulse propagating through a tenuous plasma. Based on these averaged equations, a new particle code is designed which calculates the particle trajectories on the plasma period time scale. The regime of total cavitation of the plasma is investigated. It is found that stable propagation over a long distance is possible in this regime, and that energetic electrons are produced with a simple characteristic dependence of their angle of deflection on energy. This new code allows for computationally efficient modeling of pulse propagation over great distances.

Modeling of laser wakefield acceleration atCO2laser wavelengths

“…(3) of Ref. [21] and the recognition that the generalized electron vorticity r p ÿ eA=c , which is zero initially, should always remain zero [23].…”

“…We consider an axisymmetric geometry with an axisymmetric laser pulse propagating along the axis of a cylindrical plasma channel. The slowly varying electron plasma density n describes the nonlinear plasma response to the ponderomotive action of the laser pulse, namely, the wakefield generation, and is the averaged relativistic factor of the electrons [21], i.e.,…”

“…To describe the laser pulse propagation in a plasma channel we use the following Maxwell's wave equation for the complex pulse amplitude a (see, e.g., [21,22]):…”

Generalized algorithm for control of numerical dispersion in explicit time-domain electromagnetic simulations

“…Dephasing plays a key role in determining the optimal stage length in highenergy LPA collider designs [9] and is sensitively dependent on the laser pulse group velocity, and hence dispersion. Significant theoretical and computational work has gone into LPA stage simulations, and has led to the development of new algorithms [10][11][12].…”

Energy Spread Reduction of Electron Beams Produced via Laser Wake

“…For a Gaussian laser pulse a parabolic radial density profile with a minimum on the laser axis is needed for guiding [18]. Such structures have been produced with long pulse (few nanosecond duration) lasers in low density (n e < 10 19 cm −3 ) plasmas using 1-5 T magnetic fields parallel to the laser axis to control heat transport and affect the radial electron density profile [19,20,21,22]; simulations using the code WAKE [23] have been performed using these channel parameters and indicate that these structures are suitable for guiding a subsequent laser pulse [18]. Alternatively, channel guiding has been demonstrated in capillary discharge plasmas and has produced GeV electron beams [11].…”