高压气体驱动锂球弹丸混合注入系统的研发

Integration of Massive-Gas and Lithium-Pellet Injections for Disruption Mitigation in Experimental Advanced Superconducting Tokamak

高压气体注入及弹丸注入是进行等离子体破裂缓解的最常用的两种杂质注入方式,这两种杂质注入方式在单独应用于等离子体破裂防护方面都存在一定的缺点,都不足以完全满足未来ITER等核聚变装置进行等离体破裂缓解的需求。为了整合两种杂质注入方式的优点,同时为了弥补两者在等离子体破裂缓解应用方面的补足,我们研发一套高压气体推进锂球弹丸混合注入系统,该系统实现了锂球弹丸及高压气体的同时混合注入,高压气体可以被注入到等离子体边界区域,而锂球弹丸在高压气体推动下可以实现几百米每秒的注入速度,可以注入到等离子体芯部区域,因此可以实现等离子体芯部和边界的多点同时冷却,有可能进一步增强等离子体与杂质的混合效率,进而有可能提高破裂缓解效果,其在破裂缓解方面的优越性将在2018年的EAST物理实验中进行进一步验证。通过平台标定,在0.6 MPa工作气压时,测试弹丸的最大速度可以达到250 m/s,在1.1 MPa工作气压时,测试弹丸的速度可以达到350 m/s,而在1.5 MPa工作气压时,测试弹丸的速度最大可以达到400 m/s,通过提高工作气压可以实现更高的弹丸注入速度。该系统的成功研发一方面为EAST开展等离子体破裂缓解研究工作提供了更加有效的杂质注入工具,另外一方面,相关技术突破及物理研究也可以为未来ITER开展相关研究提供借鉴。

A novel hybrid injector was developed by integrating the massive gas and lithium pellet injections to simultaneously cool down the core and boundary areas of plasma for disruption mitigation in Experimental Advanced Superconducting Tokamak （EAST）. The prototyped hybrid injector was evaluated with the lab-built test platform. The preliminary results show that the newly-designed hybrid injector worked well for disruption mitigation because of more effective cooling down and mixing of plasma and impurities in larger volume including the core and bounda- ries. For example, as the injection pressure increased from 0.6 to1 1 and to 1. 5 MPa, the fastest speeds of the injected glass pellets were measured to be 250,350 and 400 m/s, respectively. There will be still much room for Li-pellet acceleration due to its lighter density. The installation and on-line evaluation of the optimized hybrid injector in EAST were scheduled in 2018.