Vacuum applications for the Tritium Systems Test Assembly

Abstract

The Tritium Systems Test Assembly (TSTA) is a facility which will develop and demonstrate the processes for handling the fuel and exhaust from a magnetic fusion reactor using deuterium and tritium as the fuel. The TSTA facility became operational in mid 1982 and will now proceed to test and evaluate the many subsystems required to purify, separate, circulate, and reuse the deuterium/tritium gas recovered from the reactor vacuum system. At TSTA the reactor will be simulated by a large vacuum vessel into which mixtures of deuterium, tritium, and various impurities (He, CH4, H2O, NH3, C2H2) are injected. This mixture is then exhausted through the vacuum system, reprocessed and prepared for reinjection into the front end. A fusion reactor must have an enormous vacuum system to remove the mixture of fuel and impurites so that the plasma can be replenished with fresh fuel. At TSTA this evacuation is achieved with ‘‘compound’’ cryopumps. These pumps remove the deuterium and tritium by cryocondensation on a 4‐K panel. The helium is removed by cryosorption on a separate refrigerated panel. TSTA will provide the first opportunity to test several models of compound cryopumps with actual mixtures of deuterium, tritium, and helium. This paper will discuss the role TSTA has in the national magnetic fusion energy program with special emphasis on the vacuum system and preliminary experimental results.