Ultrahigh vacuum technology of tokamak

Ultrahigh vacuum (UHV) technology has played a significant role in the design, operation, upgrade and D-T demonstration experiments of modern tokamak, and it also has a great effect on the advanced high density divertor and the next generation tokamak engineering reactors. At the same time, new concepts of fusion research also improve the UHV technology. In the past 35 years, plasma density, impurity and wall condition control have been strongly coupled to pump-down and leak detection, bake-out degassing, discharge cleaning, wall conditioning, H (D,T) trap, release and recycle, wall erosion and redeposition etc. Development efforts in high performance vacuum vessel, bake and vibration tolerable UHV sealing, advanced plasma-facing components, efficient wall conditioning procedures and high capacity pumps etc made essential contributions to the control of plasma-wall interaction, improvement of fusion three products (niTiτE), and demonstration of scientific feasibility of tokamak fusion energy