Basic research of pellet injector for inertial fusion

研究了为未来的激光聚变反应堆开发燃料弹丸喷射系统所需的基本技术。该项目的目的是开发精确的速度控制技术和注入弹丸的跟踪技术。在未来的激光聚变反应堆中，燃料弹丸由直径6毫米的充氢和氚胶囊以少量IIz的重复频率注入中心。由于内爆效率强烈地依赖于辐照的均匀性，因此当激光照射燃料弹丸时，必须将其准确地定位在发射位置。目前对定心精度的理解是小于50微米。由于弹丸的注射速度约为300m/S，本规范要求检测系统的方向为10微弧度，定时为0.1微秒，由于所需的注射速度300m/S已在某地得到验证，因此我们专注于提高重复性。对于第一杆，研究了初始位置偏差对最终喷射速度的影响。结果表明，与最佳位置的偏差为100微米，速度差为10^6。可以说，对于注射系统，初始加载的精度并不是很高。对于跟踪技术，我们提出了一种由三个平板激光和三个光电探测器组成的检测系统。实验结果表明，该系统能够检测到S真实尺寸球团的通过，定时精度为10 ns，位置精度为10微米。结果表明，x轴、y轴各1套，Z(注入)轴3套x-y单元可构成未来的示踪系统。

Basic technology necessary to develop a fuel pellet injection system for a future laser fusion reactor was investigated. The project is dictated to develop precise velocity control technology and trace technology for the injected pellet.In the future laser fusion reactor, fuel pellets consisting 6-mm-diameter capsule filled with deuterium and tritium are injected into the center at repetition rate of few IIz. Since the implosion efficiency strongly depends upon the irradiation uniformity, the fuel pellet must be exactly located at the firing position when it is irradiated by laser beams. Current understanding for the centering accuracy is less than 50 micrometer. Since the injection velocity of the pellet is about 300 m/s, this specification requires the detection system with 10 micro rad in direction and 0.1 micro second in the timing.Since the required injection velocity of 300 m/s is already demonstrated somewhere, we concentrated in improving the repeatability. For the first stem, influence of deviation in the initial position on the final injection velocity was investigated. We found that a deviation of 100 micrometer from the optimized position result in velocity deference of 10^6. We can say that the accuracy of initial pellet loading is not so serious for injection system.For the trace technology, we proposed a detection system consisting of three flat laser beams and three photo detectors. We found that the system can detect the passage of s real size pellet with accuracy of 10 ns in the timing and 10 micrometer in the position. There results indicate futuer trace system can be constructed by using one set for x, and y axis each and 3 sets of x-y units for Z (injection) axis.