Disruption mitigation experiments in the JT-60U tokamak

Experiments in the JT-60U tokamak have shown that disruption deleterious effects on plasma facing components of a tokamak reactor can be greatly reduced or avoided by simultaneous puffing of small amounts of high-Z noble gases, particularly, krypton and large amounts of hydrogen gas. A high electron density caused by the intense hydrogen gas puffing amplified the radiation of High-Z atoms. In turn the stored energy was radiated and plasma was terminated quickly. The high electron density and high effective charge made by high-Z species prevents runaway electron generation. It was also found that injecting neon ice pellets during the post-disruption runaway plasma can enhance the runaway electron losses. (author)