Backscattered supercontinuum emission from high-intensity laser-plasma interactions.
We performed high-intensity subpicosecond laser-plasma interaction experiments to examine nonlinear scattering mechanisms in underdense plasmas. At incident laser intensities of 2 x 10(18) W/cm(2) the stimulated-Raman-backscattered spectrum exhibited an extremely broad, supercontinuumlike structure (Deltaomega/omega(0) > 1) extending from ~500 to >1200 nm (limited only by detector sensitivity). Large-amplitude modulations in the spectrum of the backscattered light were measured and are attributed to an interaction of the stimulated-Raman-scattered radiation with ion plasma waves.
Theory of stimulated scattering processes in laser‐irradiated plasmas
Analytic theory of the linear and nonlinear behavior of the one‐dimensional Brillouin and Raman scattering instabilities is given. Results are presented for the problems of an infinite homogeneous plasma and of a finite inhomogeneous plasma. Nonlinear fluid equations can predict backscatter energies the order of the incident laser energy; however, the size of the interaction region and nonlinear effects on the excited electrostatic wave are very important in determining the amount of backscatter. In many cases of contemporary interest for a high power laser incident on a target plasma, the latter effects can play a crucial role in reducing backscatter to a tolerable level.
A new target configuration producing an effective population inversion at energy levels of Mg XI 1s3p and 1s4p
Abstract A microtube target with lateral jet nozzle has recently been developed. Strong population inversion was observed along the whole jet nozzle between the energy level of MgXI 1s3p 1 P o 0 and that of 1s4p 1 P o 0 , while the average laser irradiance was around 3.5×10 13 W cm -2 on the inner wall of the microtube targets. A corresponding average electron temperature of 470–520 eV and density of 2×10 20 cm -3 at the inversion area of the plasma medium was measured. Possible mechanisms of the population inversion under the average high temperature condition have been analysed.