Physics study of the application of an IFEL (Induction Free Electron Laser) to CIT (Compact Ignition Tokamak)

The ECH system requirements on CIT might be met by microwaves generated by an induction free electron laser (IFEL). Design studies have assumed that the system is windowless, thus eliminating one of the most highly stressed components of the ECH system. The tradeoff for this advantage is that the IFEL is exposed to tritium diffusing from CIT. As reported in the attached appendix, we have investigated the use of cryopumping to control the tritium diffusion to the IFEL. With one to three pumping stations (depending on size) we can reduce the level of tritium in the IFEL to a level that may not pose a breathing hazard after one year of operation. In addition, adding pumping may allow hands-on maintenance after one year. Preliminary indications are that likely accident scenarios will occur slowly enough to permit valves to be closed before the IFEL is significantly contaminated.