No abstract

We have experimentally demonstrated the existence of super-broadband non-degenerated phase matching for a signal with a wavelength of 911 nm in KD*P crystal pumped with wavelength of 527nm. Parametric amplification coefficient of more than 10 7 in three cascades is achieved. This resulted in pulse energy 10mJ at the output of third cascade. It is shown that in the KD*P crystal chirped pulses of conventional femtosecond sources (a Ti:Sa laser at 911 nm and a Cr:forsterite laser at 1250 nm) can be amplified up to the level that ensures multipetawatt power after compression.

Optical elements made of KDP, DKDP crystals (Pockels elements, frequency conversion elements, phaseplates) are up to now among the most expensive and significant ones in high-power laser systems with frequency conversion into higher harmonics. Only some companies have mastered such production technology of optical elements with the aperture size up to 40x40 cm. The production is characterized by very long cycles of crystal growth and large waste at manufacturing opticai elements, which leads to an extremely high price ofthe products. An alternative technology based on rapid technology of profiled growth of crystal products and the technology of optical diamond micromilling by means of ISM-600 machines are developed now at the Institute of Applied Physics RAS. The cycle duration of the crystal product growth reduces tens times, cuffing of the grown product mto optical elements proves to be practically wasteless This leads to reduction ofproduct cost and significant shortenmg ofproduct cycle duration The quality of crystal growth and optical processing is consistent with the requirements of optical systems. This together with the described applied technologies has permitted to manufacture optical elements for a series ofhighpower lasers.

The problem of creating of high effective technology to fabricate crystal elements for high-energy laser systems is observed. It is developped the principal technology, wich permits to grow crystals blanks with given shape, dimensions and orientation.The growth rates exceed the conventional ones by more then 1 0 times. The (1 0 1) orientation KDP crystal with dimensions 380 x 450 x 50mm has been obtained. The possibility ofuse skewed " elements is considered.

Large amplitude low frequency (0.7-2.5 kHz) oscillations which are in phase across the minor radius have been observed in soft X-ray emission since the removal of limiters from HBTXlB Reversed Field Pinch for plasmas with small field reversal, F, at all toroidal currents. These oscillations. due to variations in electron temperature, are in antiphase with oscillations in plasma resistance and ion temperature and occur in the majority of discharges where the resistance is closest to its lowest value. Correlated magnetic oscillations indicate cyclic behaviour in the F-8 plane similar to that observed at high values of 8 on other experiments, where 0 is the pinch parameter.

No abstract

Problems of creating high-efficiency technology of crystal KDP, DKDP blanks production for high-power lasers using the elaborated laboratory rapid-growth technology are considered. The laboratory technology enables one to grow crystal samples of the sizes and quality close to the requirements of the ICF laser drivers. The improved technology will provide samples completely satisfying the ICF demands. It is expected that the productivity ofthe developed technology will exceed the traditional one by an order, while the cost of samples will be essentially lower than in other technologies.

No abstract