Quenching of the nonlocal electron heat transport by large external magnetic fields in a laser-produced plasma measured with imaging thomson scattering.

We present a direct measurement of the quenching of nonlocal heat transport in a laser-produced plasma by applying large external magnetic fields (>10 T). The temporally resolved Thomson-scattering measurements of the electron temperature profile show that the heat front propagation transverse to a high-power laser beam is slowed resulting in extremely strong local heating. We find agreement with hydrodynamic modeling when including a magnetic field model that self-consistently evolves the fields in the plasma.

Direct observation of the saturation of stimulated Brillouin scattering by ion-trapping-induced frequency shifts.

We report the first measurement of the saturation of stimulated Brillouin scattering (SBS) by an ion-trapping-induced frequency shift, which was achieved by directly measuring the amplitude and absolute frequency of SBS-driven ion-acoustic waves (IAW). A frequency shift of up to 30% and a simultaneous saturation of driven IAW and SBS reflectivity were observed. The scaling of the frequency shift with the IAW amplitude compares well with theoretical calculations. We have further measured fast 30 ps oscillations of the SBS-driven IAW amplitude induced by the frequency shift.

Intense high-energy proton beams from Petawatt-laser irradiation of solids.

An intense collimated beam of high-energy protons is emitted normal to the rear surface of thin solid targets irradiated at 1 PW power and peak intensity 3x10(20) W cm(-2). Up to 48 J ( 12%) of the laser energy is transferred to 2x10(13) protons of energy >10 MeV. The energy spectrum exhibits a sharp high-energy cutoff as high as 58 MeV on the axis of the beam which decreases in energy with increasing off axis angle. Proton induced nuclear processes have been observed and used to characterize the beam.

Phase conjugation and pulse compression of KrF-laser radiation by stimulated Raman scattering.

An experimental investigation of phase conjugation and pulse compression by stimulated Raman scattering in methane gas using a narrow-linewidth KrF-laser pump is presented. Good spatial reproduction of the pump beam is observed at reflectivities of up to 80%. With a pump-pulse duration of 25 nsec, backward Stokes pulses of 5-nsec duration with 40% of the 100-mJ pump energy were obtained.

High Temperature Absorption in CO(2) at 10.6 microm.

Measurements of the temperature variation of the resonant absorption coefficient in shock heated CO(2) gas (350-1600 K) using a laser source operating on the P(20) or P(18) transition are reported. Values obtained are compared with theory allowing for mixed mode contributions to absorption as well as dependence of the optical broadening cross section on temperature.