Shattered pellet injection (SPI) has been selected as the baseline technology for the disruption mitigation (DM) system for ITER. Typical SPI utilizes cryogenic cooling to desublimate low pressure (<100mbar) gases onto a cold zone within a pipe gun barrel, forming a cylindrical pellet. Pellets are dislodged from the barrel and accelerated using either a gas driven mechanical punch or high-pressure light-gas delivered by a fast-opening valve. SPI technology developed at Oak Ridge National Laboratory is currently deployed and operational on DIII-D, JET, and KSTAR. These SPI systems are used in experiments for physics scaling to ITER thermal mitigation and runaway electron dissipation/avoidance. The pellet sizes used for these machines are in the range of 4 to 12.5mm in diameter with length to diameter ratios (L/D) of ∼1.5. The current plan for ITER SPI is to utilize pellets that are 28.5mm in diameter with an L/D of ∼2. The large pellet sizes, high steady-state magnetic fields, and limitations of operating in a radiation environment render much of the current technology unusable. In addition to technology improvements, a deeper understanding of pellet material properties, formation, and release is being developed for implementation in future SPI designs, specifically ITER.

破碎颗粒注入 (SPI) 已被选为 ITER 中断缓解 (DM) 系统的基准技术。典型的 SPI 利用低温冷却将低压 (<100mbar) 气体凝华到管枪枪管内的冷区，形成圆柱形弹丸。使用气体驱动的机械冲头或由快速打开的阀门提供的高压轻气体将颗粒从枪管中取出并加速。橡树岭国家实验室开发的 SPI 技术目前已在 DIII-D、JET 和 KSTAR 上部署和运行。这些 SPI 系统用于将物理缩放到 ITER 热缓解和失控电子耗散/避免的实验。用于这些机器的颗粒尺寸在直径为 4 到 12.5 毫米的范围内，长径比为 ( L /D ) 约 1.5。ITER SPI 目前的计划是使用直径为 28.5 毫米、L / D为~2 的颗粒。大颗粒尺寸、高稳态磁场以及在辐射环境中操作的限制使得当前的大部分技术无法使用。除了技术改进外，正在开发对颗粒材料特性、形成和释放的更深入了解，以在未来的 SPI 设计中实施，特别是 ITER。