The integrated KSTAR vacuum pumping system

The Korea Superconducting Tokamak Advanced Research (KTAR) tokamak device is capable of a long pulse (up to 300s) plasma operation utilizing superconducting coils with a cryostat boundary. Its well-designed integrated vacuum pumping system including torus, cryostat, neutral beam injector (NBI), and diagnostics pumping subsystems is essential to achieve the physics requirements set in the Physics Requirements Document (PRD) for the optimized plasma performance and continuous operation. The primary goal of the pumping system is maintaining the appropriate pressures in torus vacuum vessel during various operational modes: plasma discharge, glow discharge cleaning, vacuum vessel bake-out, and regeneration of the in-vessel cryocondensation pump. A trade study has been performed to assess the performance of the two pumping duct geometries, bottom vertical ports and NBI-type ports.