Kim Jung-Hwa, Kim Young-Gi, Kim Doyeon, Lee Jong-Ha, Hwang Y S
Department of Nuclear Engineering, Seoul National University, Seoul 08826, Republic of Korea.
United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
Rev Sci Instrum. 2021 Apr 1;92(4):043549. doi: 10.1063/5.0043792.
A Thomson scattering (TS) system has been utilized to measure the electron temperature and density of the core region of Versatile Experiment Spherical Torus (VEST). Recently, the laser injection system is successfully upgraded adopting the burst laser with the repetition rate of 1 kHz and the energy of 2 J. Furthermore, improved collection optics with additional polychromators and a 32-channel fast digitizer are prepared to observe the fast time evolution of radial profiles. This improvement is essential to study fast phenomena such as internal reconnection event (IRE). We increase the TS signal and reduce the stray light by introducing new filters having better optical properties such as high optical density at 1064 nm, transmission, and reflectance. Moreover, the optimum reverse bias voltages are newly set to make the system operational independent of the background radiation. As a result, 1 kHz radial profiles of the core electron temperature and density are measured for the first time, showing characteristics of IREs in VEST.
一个汤姆逊散射（TS）系统已被用于测量通用实验球形托卡马克（VEST）核心区域的电子温度和密度。最近，激光注入系统成功升级，采用了重复频率为1kHz、能量为2J的脉冲激光。此外，还配备了带有额外多色仪和32通道快速数字化仪的改进型收集光学器件，以观测径向分布的快速时间演化。这一改进对于研究诸如内部重连事件（IRE）等快速现象至关重要。我们通过引入具有更好光学性能的新滤光片，如在1064nm处具有高光密度、透过率和反射率，来增加TS信号并减少杂散光。此外，新设置了最佳反向偏置电压，以使系统能够独立于背景辐射运行。结果，首次测量到了核心电子温度和密度的1kHz径向分布，显示出VEST中IRE的特征。
