[en] For smoothing and shaping the on-target laser patterns flexibly in high-power laser drivers, a scheme has been developed that includes a zoom lens array and two-dimensional smoothing by spectral dispersion (SSD). The size of the target pattern can be controlled handily by adjusting the focal length of the zoom lens array, while the profile of the pattern can be shaped by fine tuning the distance between the target and the focal plane of the principal focusing lens. High-frequency stripes inside the pattern caused by beamlet interference are wiped off by spectral dispersion. Detailed simulations indicate that SSD works somewhat differently for spots of different sizes. For small spots, SSD mainly smooths the intensity modulation of low-to-middle spatial frequency, while for large spots, SSD sweeps the fine speckle structure to reduce nonuniformity of middle-to-high frequency. Spatial spectra of the target patterns are given and their uniformity is evaluated.

[en] The authors have developed and successfully demonstrated the 'point projection absorption spectroscopy (PPAS)' technique to record keV absorption spectra in coronal regions of laser produced germanium plasmas which provides spatial information in coronas with a resolution of ∼24μm and can freeze the motion of the expanding plasmas at about 25 ps level. The 1-D hydrocode JB19 were used to simulate the experiment in planner geometry over a range of intensity and the predictions are compared to the observations. Such comparison can be useful in validating parts of the codes used for gain predictions of soft X-ray laser transitions

[en] The authors present the temporally and spatially resolved feature of the side scattered 3ω₀/2 harmonic emission induced by a single laser spot with ten-micron-radius-scale in a preformed laser plasma. The close relation of the harmonic emission with such a small scale laser self-focusing filamentation has been discussed in detail. It is suggested that the side scattered harmonic signal from a underdense region as low as 0.05 n_c may be caused by the Langmuir wave and/or ion-acoustic wave scattering induced by laser dynamic filamentation

[en] Short communications only

[en] Both temporally and Spectrally resolved fine structures of 90 deg lateral 3/2ω₀ harmonic emission were experimentally observed. The existence of 3/2ω₀ harmonic filaments is attributed to the 3/2ω₀ harmonic radiation emitted from neighborhood of the bottom of moving filament, about n_c/4 away from it. The double hump structure with intense red hump of laterally emitted 3/2ω₀ spectrum can also be explained by Doppler correction besides the thermal correction due to fast moving TPD process occuring in the unstable filaments. Estimation of both red and blue shifts using our simple model is well consistent with experimental results. Experiments showed that the 3/2ω₀ emission was obviously suppressed by using broad band laser owing to more uniform illumination on the target surface and broad band effect. These may be promissing for superhot electron suppression

[en] From two dimensional steady state plasma fluid equations, assuming a balance of radial electron thermal pressrue and radial pondermotive force in the cylindrical symmetric distribution of electron density in laser irradiated region, the analytical results have been deduced of radial electron density dip structure in the laser field region and the axial electron density profile steepening near the critical density due to the pondermotive force. The analytical results are consistent with the experimental results measured by a 266 nm UV optical pbobe

[en] The emission and measurement of bremsstrahlung spectrum from laser plasma are discussed and the bremsstrahlung spectrometer and the measured results are described

[en] SG-II laser facility was improved on design and engineering last year. After the improvement, 8 beam's SG-II laser facility is able to deliver ≥6KJ, 1ns, 1ω₀ energy or ≥8TW, 100ps, 1ω₀ output in routine operation with high optical quality, achieving its 1ω₀ final goal. This work is the first successful practice by developing two sets of double pass, co-axial 2X2 array main amplifier in an aperture of φ200mm each beam. The improved facility feature and some of the precision works are introduced

[en] The author present here the studies of laser imploded glass microballoons by the newly developed time-resolved four-frame X-ray shadowgraphy. The simulation results of one-dimensional Lagrangian hydrodynamical computation code (WL code) are in good agreement with the diagnostic experiments. The joint effort of the diagnostic experiments and theoretical simulations is crucial to understand laser implosion dynamics

[en] A phenomena of spontaneous current generated from laser plasma is studied. It was produced from several plane target made from Rh, Ag and Cu irradiated with high power laser light. The pulse-width, output energy and wavelength of the laser were 200 ps (FWHM), 0.1-4 J and 1.06 μm, respectively. At the focus spot of the target irradiated with laser, a spontaneous current density as high as 10₇ A/cm² was found in the experiment