Shen Y C, Fan Y, Zhang H M, Lyu B, Lin Z C, Yin X H, Wang F D, Fu J, Ji H J, Zeng C, Sun B, Mao L Y
School of Physics and Materials Engineering, Hefei Normal University, Hefei 230601, China.
Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
Rev Sci Instrum. 2024 Aug 1;95(8). doi: 10.1063/5.0215727.
The Laser Blow-Off (LBO) impurity injection system is a crucial tool for studying impurity transport and plasma behavior. Conducting proactive impurity transport research is challenging on experimental advanced superconducting tokamak (EAST) due to the uncontrollable generation of impurity sources; therefore, it is necessary to develop a laser blow-off impurity injection system for injecting controlled trace impurity particles. This study presents the design and test results of an LBO system for the EAST. The system aims to provide precise and repeatable control over the timing and quantity of impurity injection. The system primarily consists of a laser source, two mirrors, a moveable focusing lens, a target material, and a vacuum system. The movement of the focusing lens is achieved by a three-dimensional displacement system. The operation of the system is completed by a remote control system. With the accurate control system, the laser spot diameter is adjustable, allowing for modification of impurity injection quantity. The test results demonstrate that the system can rapidly detect external trigger signals and ensure precise timing for the impurity injection. Furthermore, this system can also quickly change the focal point of the laser spot, addressing the requirements for impurity injections during the experiments with less than 0.4 mm position error for laser spot focusing. Test results have shown that the aluminum film material can be peeled off by the LBO system when the laser energy exceeds 650 mJ and the smallest ablation spot is about 1 mm. This study is of significant importance for conducting plasma impurity transport research on the EAST.
激光吹除（LBO）杂质注入系统是研究杂质输运和等离子体行为的关键工具。由于杂质源的产生不可控，在实验先进超导托卡马克（EAST）上进行主动杂质输运研究具有挑战性；因此，有必要开发一种用于注入可控微量杂质颗粒的激光吹除杂质注入系统。本研究介绍了用于EAST的LBO系统的设计和测试结果。该系统旨在对杂质注入的时间和数量提供精确且可重复的控制。该系统主要由激光源、两面镜子、一个可移动聚焦透镜、靶材和一个真空系统组成。聚焦透镜的移动通过三维位移系统实现。系统的操作由远程控制系统完成。借助精确的控制系统，激光光斑直径可调，从而可以改变杂质注入量。测试结果表明，该系统能够快速检测外部触发信号并确保杂质注入的精确时间。此外，该系统还能快速改变激光光斑的焦点，满足实验期间杂质注入的要求，激光光斑聚焦位置误差小于0.4毫米。测试结果表明，当激光能量超过650毫焦时，LBO系统可以剥离铝膜材料，最小烧蚀光斑约为1毫米。本研究对于在EAST上开展等离子体杂质输运研究具有重要意义。
