“强光一号”装置上部分Z箍缩实验结果的物理分析

从原子的电离能和维持等离子体所需能量出发，给出了估算任一元素材料，要产生任一壳层的X射线辐射，每个离子(原子)所需要的基本能量和要达到的内爆箍缩速度的方法.对“强光一号”加速器上典型的氪喷气和部分钨丝阵Z箍缩实验的电流和电压波形所蕴涵的丰富物理信息进行了分析，得到了电感和洛伦兹(Lorentz)力做功等物理量的变化规律以及负载参数变化对它们的影响.该电感与基于壳层模型计算出的电感有较大的差异.前者随箍缩开始而缓慢增大，甚至在箍缩到心和飞散后还在增大，最后大致稳定在100 nH附近.差异可能是由于壳层模型过于简化和电流电压的测点同负载有一定的距离而造成的.当丝阵直径为8 mm时，洛伦兹力做功最大；当丝阵直径相同时，丝数较大时，洛伦兹力做功也较大.同时还对该加速器的喷气和丝阵负载的线质量进行了优化，表明也是直径为8 mm的钨丝阵为最佳负载，这同实验的优化结果也一致.

Physical analysis of the certain results in Z-pinch experiments on the "Qiang Guang-I" generator

Starting from the energy necessary for atomic ionization and plasma maintaining, a method is developed to estimate the required energy and implosion velocity for a material to emit a certain shell X-ray radiation in a Z-pinch. The typical load current and voltage in Z-pinch process on “Qiang Guang-I” generator are analyzed to obtain the inductance and the work done by Lorentz force, as well as the effect of load parameters on them. The inductance is not in good agreements with that calculated from the theory based on the shell model of Z-pinch, possibly due to the over simplification of the model and the measurement limitations, such as the measuring points of the current and voltage are always several centimeters away from the load. It is found in the experiments that the inductance increases with the load current until the end of the X-ray radiation pulse, and is saturated at ～100nH. The work done by Lorentz force is maximal when the diameter of tungsten wire array is 8 mm in our experiments. The work done to the load with more wires is greater than that to the load with less wires if the diameters of the wire arrays are the same, say 8 or 10 mm. At the same time, the calculation for optimized masses per unit length of gas-puff and wire array load was carried out for the “Qiang Guang-I” generator on 1.6MA current level. The optimized results show that the tungsten wire array with 8 mm diameter should be the best load for this generator. This is consistent with the experimental result on the “Qiang Guang-I”.