Plasma fluctuations driven by a randomized laser beam

Nonthermal fluctuations produced by a randomized laser beam in an underdense plasma have been investigated in the regime of a nonlocal electron transport. A nonlocal closure to linearized fluid equations for fluctuating hydrodynamic variables properly accounts for inverse bremsstrahlung heating and ponderomotive force effects. It has been shown that a typical randomized laser beam as used in the inertial confinement fusion experiments can generate large amplitude density fluctuations well above thermal levels. An expression for the Thomson scattering cross-section from these fluctuations has been derived and discussed. The vortical velocity and magnetic field fluctuations can also be enhanced with the vortical plasma velocity reaching values comparable to the ion acoustic velocity.