Plasma parameters in laser imploded targets from space-resolved X-ray spectroscopy

Abstract

Plasma densities and temperatures are deduced from soft X-ray emission spectra of neon-filled glass microballoons imploded by a 0.2 terawatt laser. Spatial resolution allows separate characterisation of the ablation plasma, the imploded glass and the compressed gas. Comparison with computer simulations of the implosion shows sensitivity to models for energy transport by hot electrons.

Silicon Satellite Spectra from Laser-Imploded Microballoons

“…These spectra are recorded using a PET crystal and a 10-/im-wide slit resulting in a 12-jum spatial resolution. 1 The instrumental spectral linewidth, determined by the source size and the rocking curve of the crystal, is 4 mA.…”

Shock wave generation in thin foils using lasers and ion beams

“…with& the fractional absorption; Zand X are again measured in units of 1014 W cm-2 and pm respectively, This model does not include transport effects which can carry the ablation front to far higher densities (Key et a1 1979) and the pressures actually attained are somewhat higher. Although the absorption f a increases with decreasing wavelength, the strong dependence shown by equation (3.1) is damped out to a large extent by the various transport mechanisms, and from our calculations below we find that a rough fit to the shock pressure is…”

Atomic phenomena in dense plasmas

“…Also, numerous laboratories have published shapes of lines emitted by hydrogenic .ms in laser-heated plasmas (cf. Yaakobi et al, 1977;Key et al, 1979), and then matched them to computed profiles in order to infer plasma densities-Hi vever, it is not known how accurate the theoretical profiles actually are because there were no independent means of determining N • Until such additional information is obtained, plasma densities inferred from Stark-broadened hydrogenic ion lines are uncertain, and may be accurate only to within a factor of 2 or so.…”

“…However, even though their dimension is small, s < 10 cm, very dense 47 -*Mi laboratory plasmas can have significant optical depths at iesonance line frequencies. When this happens, spectral line radiation is strongly nidified, a fact evidenced in several recent studies involving ICF plasmas (Irons, 1975;Weisheit ^t_ali., 1975;Key _et_a^., 1979;Duston and Davis, 1980). The thecry of radiation transfer in optically thick lines (and these lines'…”

“…Besides the spectral data provided by conv -itional means, spatial and temporal resolution of ICP plasmas is provided by x-ray photographs from pinhole and streak cameras (Yaakobi and Goldman, 1976;»Vttwood et al • , 1977;Lee and Rosen, 1979;Key et al, 1979).…”