Yu Yaowei, Kim Young-Ok, Kim Hak-Kun, Kim Hong-Tack, Kim Woong-Chae, Kim Kwang-Pyo, Son Soo-Hyun, Bang Eun-Nam, Zhuang Huidong, Chen Zhongyong, Hong Suk-Ho, Yoon Si-Woo
National Fusion Research Institute, Daejeon 305-806, South Korea.
Rev Sci Instrum. 2012 Dec;83(12):123509. doi: 10.1063/1.4772573.
Massive gas injection (MGI) system was developed on Korea Superconducting Tokamak Advanced Research (KSTAR) in 2011 campaign for disruption studies. The MGI valve has a volume of 80 ml and maximum injection pressure of 50 bar, the diameter of valve orifice to vacuum vessel is 18.4 mm, the distance between MGI valve and plasma edge is ~3.4 m. The MGI power supply employs a large capacitor of 1 mF with the maximum voltage of 3 kV, the valve can be opened in less than 0.1 ms, and the amount of MGI can be controlled by the imposed voltage. During KSTAR 2011 campaign, MGI disruptions are carried out by triggering MGI during the flat top of circular and limiter discharges with plasma current 400 kA and magnetic field 2-3.5 T, deuterium injection pressure 39.7 bar, and imposed voltage 1.1-1.4 kV. The results show that MGI could mitigate the heat load and prevent runaway electrons with proper MGI amount, and MGI penetration is deeper under higher amount of MGI or lower magnetic field. However, plasma start-up is difficult after some of D(2) MGI disruptions due to the high deuterium retention and consequently strong outgassing of deuterium in next shot, special effort should be made to get successful plasma start-up after deuterium MGI under the graphite first wall.
2011年韩国超导托卡马克先进研究装置（KSTAR）运行期间开发了用于破裂研究的大规模气体注入（MGI）系统。MGI阀的容积为80毫升，最大注入压力为50巴，阀孔到真空容器的直径为18.4毫米，MGI阀与等离子体边缘的距离约为3.4米。MGI电源采用一个1毫法的大电容器，最大电压为3千伏，阀门可在不到0.1毫秒内打开，MGI的量可通过施加的电压来控制。在KSTAR 2011年运行期间，在等离子体电流为400千安、磁场为2 - 3.5特斯拉、氘注入压力为39.7巴、施加电压为1.1 - 1.4千伏的圆截面和限制器放电平顶期间触发MGI来进行MGI破裂实验。结果表明，适量的MGI可以减轻热负荷并防止逃逸电子，并且在MGI量较大或磁场较低的情况下，MGI的穿透更深。然而，在一些D(2) MGI破裂后，由于氘的高滞留以及因此在下一次放电中氘的强烈脱气，等离子体启动变得困难，在石墨第一壁下进行氘MGI后，需要做出特别努力才能成功启动等离子体。
