Vacuum Pumping System for ITER's Deuterium Tritium Operational Campaign

Abstract

SummaryIn the ITER fusion experiment the torus vacuum pumping system is mainly involved in pumping plasma exhaust gases consisting of Deuterium/Tritium (DT) and trace quantity of helium. The currently proposed plasma operation plan for the six torus cryopumps is staggered for all fueling rate and plasma durations and therefore variable tritium inventories need to be handled. The ITER cryopumps and the backing vacuum pumping system are custom made tritium compatible pumping trains. Their compliant matrix not only asks for pumping efficiencies and hydrogen confinement but also respecting the specific tritium and deuterium (DT) inventories for measures on radiation protection and fire safety. In this article, we present a possible operation plan for torus vacuum pumping system in combinations with roughing pump trains for the ITER baseline plasma scenario. The operation of the vacuum system is driven by DT inventories in the different pumps and building sectors.The primary vacuum pump is torus cryogenic pump (TCP) followed backing roughing pump trains comprise the cryogenic viscous flow compressor (CVC), tritium compatible scroll and Roots pumps. The TCPs are regenerated during timed intervals for an uninterrupted and safe torus operation. Next to the demanding long pulse operation (1 hour) we present an operation plan for inductive short pulse (450 s), hybrid pulse (1000 s) and dwell time vacuum pumping operations [1]. However, the inductive and hybrid pulses are not as critical as long pulse operation pertaining to tritium and hydrogen inventory management.