REDISTRIBUTION OF SOLID FUEL LAYER IN LASER FUSION TARGET BY ELECTRODE-LESS DISCHARGE OF MICROWAVE

研制了一种激光聚变堆低温靶的等离子体沉积技术。将一个直径为6 mm的石英壳置于微波腔中，冷却至10 K，以将适量的氘冷冻在其中。通过在空腔中引发辉光放电，成功地将壳层中不均匀的固体氘层重新分布为均匀的固体氘层。这个时间常数比氚衰变引发的热驱动的时间常数小得多。该时间常数较短，有利于未来激光聚变反应堆系统的发展，因为它可以减少芯块工厂中的氚库存。2）再分布时间常数主要由壳体的冷却性能决定，而时间常数对微波功率的依赖性较弱。降低冷却氦气的温度是缩短时间常数的最有效方法。3）固体氘，最初由于裂纹是不透明的，通过辉光放电加热变成透明的。通过升华/沉积循环朝向热源去除固体中的裂纹。这对获得高质量的激光聚变靶固体燃料层具有重要意义。

Plasma layring technique to make a cryogenic target for a laser fusion reactor has been developed. A 6-mm-diameter quartz shell housed in a microwave cavity was cooled to 10 K to freeze appropriate amount of deuterium inside. A nonuniform solid deuterium layr in the shell was successfully redistributed into uniform one by initiating a glow discharge in the void.1) The time constant for redistribution was 80 second. This time constant is much less than that driven by heat initiated by tritium decays. This short time constant is beneficial for the future laser-fusion reactor-system since it can reduce the tritium inventory in a pellet factory.2) The time constant for redistribution is primary determined by cooling performance of the shell and the time constant has week dependence on the power of the microwave. Reducing the temperature of the cooling helium is most effective to shorten the time constant.3) Solid deuterium, which was initially opaque due to cracks, turned into transparent by heating with the glow discharge. Cracks in the solid were removed toward the heat source through a sublimation / deposition cycle. This is an important result to obtain a high quality solid fuel layr for the laser fusion target.