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X-ray observations of tungsten wire array Z-pinch implosions on QiangGuang-1 facility
Zhang Fa-Qiang(章法强), Li Zheng-Hong(李正宏), Xu Ze-Ping(许泽平), Xu Rong-Kun(徐荣昆), Yang Jian-Lun(杨建伦), Guo Cun(郭存), Xia Guang-Xin(夏广新), Chen Jin-Chuan(陈进川), Song Feng-Jun(宋凤军), Ning Jia-Min(宁家敏), Wang Zhen(王真), Xue Fei-Biao(薛飞彪), Li Lin-Bo(李林波), Qin Yi(秦义), Ying Chun-Tong(应纯同), and Liu Guang-Jun(刘广均)
Chinese Physics, 2006, 15 (9):
2058-2064.
DOI: 10.1088/1009-1963/15/9/028
Z-pinch experiments with two arrays consisting, respectively, of 32 4-μm- and 6-μm-diameter tungsten wires have been carried out on QiangGuang-1 facility with a current rising up to 1.5MA in 80ns. At early time of implosion, x-ray framing images show that the initial emission comes from the central part of arrays, and double clear emission rings, drifting to the anode and the cathode at 5×106cm/s and 2.4×107cm/s respectively, are often produced near the electrodes. Later, in a 4-μm-diameter tungsten wire array, filamentation caused by ohmic heating is prominent, and more than ten filaments have been observed. A radial inward shift of arrays starts at about 30\,ns earlier than the occurrence of the x-ray peak power for both kinds of arrays, and the shrinkage rate of emission region is as high as 1.7×107cm/s in a 4-μm-diameter tungsten wire array, which is two times higher than that in a 6-μm one. Emission from precursor plasmas is observed in implosion of 6-μm-diameter tungsten wire arrays, but not in implosion of a 4-μm-diameter tungsten wire array. Whereas, in a 4-μm-diameter tungsten wire array, the soft x-ray emission shows the growth of m=1 instability in the plasma column, which is caused by current. The reasons for the discrepancy between implosions of 4-μm- and 6-μm-diameter tungsten wire arrays are explained.
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