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The effects of laser bandwidth on stimulated Raman scattering (SRS) instability in underdense plasma are studied by particle-in-cell simulations. In the simulations, sinusoidal frequency modulation of the incident laser pulse is used. By changing the size of bandwidth, it is shown that the linear growth of SRS can be suppressed considerably, provided the laser bandwidth is much larger than the SRS linear growth rate. Simulations also show that by choosing the proper frequency modulation parameters or decreasing the linear growth rate of SRS, the inhibitory effects become more obvious. The plasma electron temperature tends to weaken the bandwidth effects especially when it is over a keV level. The laser bandwidth can only increase the time duration for linear growth but cannot diminish the instability completely. [ABSTRACT FROM AUTHOR]

Effects of relativistic electron temperature on stimulated Raman scattering and stimulated Brillouin scattering instabilities for high intensity lasers propagating in underdense plasma are studied theoretically and numerically. The dispersion relations for these instabilities are derived from the relativistic fluid equation. For a wide range of laser intensity and electron temperature, it is found that the maximum growth rate and the instability region in k-space can be reduced at relativistic electron temperature. Particle-in-cell simulations are carried out, which confirm the theoretical analysis [ABSTRACT FROM AUTHOR]

Based on particle-in-cell simulations, ion acceleration by collisionless electrostatic shock waves in the interaction of intense laser pulses with solid targets containing two ion species of different charge-to-mass ratios R is studied. The acceleration processes of the ions with different R and located in different regions of the target have been considered. Simulations also show that ions with larger R can be reflected and accelerated dramatically between two oppositely propagating shocks generated in plasma dominated by ions with smaller R. The studies suggest a new way to generate high energy ions. The involved phenomena may also occur in space and astrophysical plasmas. [ABSTRACT FROM AUTHOR]