Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

A high-power KrF system has been used to heat solid targets with laser energies of up to 1 J in 3 ps. Single-shot irradiances of up to 1017 W-cm-2 were achieved at the target surface. A number of diagnostics were used to investigate the plasmas produced. When an ASE background containing about 20% of the short-pulse energy in a 10-ns interval was present, the X-ray spectra indicated an electron temperature of about 400 eV and a density of a few times 1022 cm-2. When the prepulse level was kept below 10-3 of the main pulse, measurements indicated plasmas with temperatures of 400 eV at close to solid density. The production of hot electrons was investigated using titanium targets overcoated with CH, and observing the Ti Kα emission. These measurements also confirmed the low prepulse level, since Kα emission was weak when only 0.5 μm of plastic overcoat was used. The experimental results were simulated with a 1-D hydrocode.

Abstract:

A novel technique of time-resolved monochromatic X-ray imaging has been used to measure the spatial variation of burn through time of an ablator layer on spherical targets irradiated by twelve laser beams of wavelength 0.53 μm and pulse duration 0.8 ns at adsorbed irradiance up to 1014 W cm-2. The effect of beam overlap on uniformity has been studied. © 1988.