Jiang Zhiyuan, Wu Jian, Zhang Daoyuan, Chen Ziwei, Wang Zhenyu, Shi Huantong, Li Xingwen, Qiu Aici
State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049, China.
Rev Sci Instrum. 2021 Sep 1;92(9):093502. doi: 10.1063/5.0048319.
Measurement of the magnetic field distribution in Z-pinch experiments remains an ongoing challenge. We present a method of measuring the radial distribution of the magnetic field around a copper rod using Zeeman splitting of sodium (Na) emission lines, in which an Na layer is formed by the laser ablation of NaCl crystals on a load surface. The load consists of a copper rod of 2 mm diameter and is pre-covered on its surface by the NaCl crystals. An 8 ns pulsed laser with an energy of 1 J and wavelength of 532 nm is focused on the crystals. The Na plasma is produced and expands from the surface of the copper rod into a vacuum. After applying a pulsed current with a peak value of 375 kA to the load, the Na 3s-3p doublet displays significant Zeeman splitting patterns. The self-luminosity of the Na plasma is recorded by a spectrometer coupled with an intensified charge-coupled device camera from an end-on view to eliminate the effects of different observing angles and Doppler shifts. We determine the magnetic field by fitting the measured spectra with the calculated results of the Voigt profile. The measurable range of radial position is 5-7 mm, and the corresponding magnetic field is 5-15 T. The averaged error of curve fitting is less than 12%.
在Z箍缩实验中测量磁场分布仍然是一个持续存在的挑战。我们提出了一种利用钠（Na）发射线的塞曼分裂来测量铜棒周围磁场径向分布的方法，其中通过在负载表面激光烧蚀NaCl晶体形成Na层。负载由直径为2毫米的铜棒组成，其表面预先覆盖有NaCl晶体。将能量为1焦耳、波长为532纳米的8纳秒脉冲激光聚焦在晶体上。产生的Na等离子体从铜棒表面扩展到真空中。在向负载施加峰值为375千安的脉冲电流后，Na 3s - 3p双重态显示出明显的塞曼分裂模式。通过与增强型电荷耦合器件相机耦合的光谱仪从端视图记录Na等离子体的自发光，以消除不同观测角度和多普勒频移的影响。我们通过将测量光谱与沃伊特轮廓的计算结果进行拟合来确定磁场。径向位置的可测量范围是5 - 7毫米，相应的磁场是5 - 15特斯拉。曲线拟合的平均误差小于12%。
