The space charge effect on residual energy of electrons in optical-field-ionized plasmas is studied in detail by a cloud-in-cell simulation. It is found that a moderate space charge field can restrain ponderomotive heating and cause a transfer of a part of the kinetic energy of electrons into potential energy so that the residual energy of electrons can be reduced effectively. The effects of inverse Bremsstrahlung heating, stimulated Raman scattering and radiation on electron temperature are also briefly discussed. Comparison is made between our results and experimental data.

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In this paper, an one and a half dimensional (1(1/2)-D, one space dimensionand two velocity dimension) plasma cloud-in-cell simulation code (CIC) has beendeveloped. It is used to study SRS in laser-plasma targets from the Shenguang-12# Nd-glass laser facility (λ=1.053μm,τ= 850ps IL= 3×1014—3×1015W/cm2). The results on the linear growth rates of the scattering electromagnetic waves and Lan-gmuir waves and nonlinear saturation are obtained in detail. Other results such as the time development of the electron distribution function and temperature and fraction of hot electron are also presented. In addition,temperature of thermal electron (1.4-2.5keV) in the underdense coronal plasma region is determined by spectrum analysis of SRS light, as well as contour figure for density distribution and averagedensity (0.12-0.14nc, n=1/4nc). These results agree with experiments.

In this paper, a physical model and numerical method in cloud-in-cell (CIC) scheme for simulation of weak collisional effects are proposed. Collisions are introduced at reconstruction time in terms of a one-dimensional Fokker–Planck operator. The friction term of the collision operator is equivalent to the introduction of a velocity-dependent acceleration a (u)= –uγ (u) into the equation of motion of the, particles. The diffusion term is represented by finite differences over the nonuniform velocity grid. Collisional relaxation, of two Maxwellian beams. is studied. The numerical results are in good agreement with the analytical values.

We have developed one-and a half-dimensional (one space dimension and two velocity components) relativistic electromagnetic cloud-in-cell simulation (CIC-R) code which is suitable for simulating the free-electron laser process. Using CIC-R we have simulated the temporal evolution of the free-electron laser, and obtained the results on the linear growth rates of the unstable spectrum and the dispersion relation of the coupling between the electromagnetic waves and electrostatic waves which agree with the theory. Other results such as the time development of the electron distribution function, nonlinear saturation and the efficiency of energy conversion are also presented in detail.