We report high-efficiency high-power uv generation at 266 nm by frequency quadrupling of Nd laser using two deuterated KDP crystals. An angle-tuned type-II phase-matched (eoe-interaction) deuterated KDP crystal is used for doubling 1.064 μm and a temperature-tuned 90° phase-matched deuterated KDP crystal is used, for the first time, for doubling 532 nm to 266 nm. Results indicate that an average uv power of several watts with an over-all quadrupling efficiency of around 20% is obtainable, and that high peak uv power on the order of 10 GW with an efficiency of greater than 35% can be expected for subnanosecond pulses. The high peak uv power is potentially useful for fusion studies.

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Plasmoids have been generated in a low-powered theta pinch and accelerated into a uniform longitudinal dc magnetic guide field. The guide field was used to guide the plasmoids into a region between two colinear dc mirrors. The motion of the plasmoids was studied by means of detector coils arranged to measure the diamagnetic effect of the plasmoids. It was found that the plasmoids move in the guide field with uniform velocity, are reflected efficiently by properly chosen mirror fields, and are apparently stable for an observed period of 25 μsec. A pulsed gating coil was arranged in one of the dc mirrors so as to weaken the mirror and allow plasmoids to be gated through the mirror by pulsing the gating coil in the correct phase. Attempts to capture plasmoids between the two mirrors resulted in the plasmoids losing their structure after two reflections between the mirrors and then beginning to expand along the guide field lines. Some measurements were made to determine microscopic characteristics of the plasmoids.

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