Siebe Jorna

Hydrodynamic stability of a laser‐driven plasma

The hydrodynamical stability of a laser‐driven plasma is investigated by analytically and numerically solving the set of coupled conservation equations of hydrodynamics to first order. The calculations are illustrated by a series of graphs showing the time evolution of the state variables of a laser‐driven deuterium‐tritium fusion plasma.

Laser‐induced instabilities in homogeneous plasmas

A linearized theory is presented for the dominant instabilities in a laser‐driven homogeneous plasma. The distinction between convective and absolute instabilities, and their effect on thresholds in finite plasmas, is especially emphasized. Thus, it is found that the effective thresholds for stimulated Brillouin and Raman scattering are higher than those generally quoted. The analysis is further extended to two dimensions, and it is shown that stimulated Brillouin scattering is primarily excited in the backward direction. The broader backscattering profile for stimulated Raman scattering exhibits a cutoff angle approaching 90° near a “critical” surface at one‐fourth the critical density. At this density a strong instability is predicted corresponding to the excitation of Langmuir waves.

Atmospheric Depolarization and Stimulated Brillouin Scattering

The effect of electrostrictively induced stimulated Brillouin scattering on atmospheric depolarization is studied. Solutions for steady-state and transient conditions are obtained.

Stimulated backward Brillouin scattering in laser heated plasmas

The dispersion relation for backward‐stimulated Brillouin scattering shows that near threshold the most unstable reflected wave rapidly outruns a laser driven underdense plasma. Laser energy absorption may, however, be affected at power flux densities above 1015 Ws/cm2 for 1.06 μ radiation.