Vacuum system design for the 300m gravitational wave laser interferometer in Japan (TAMA300)

TAMA300, a laser interferometric detector for gravitational waves, involves two vacuum ducts of length 300 m and 400 mm diameter and nine vacuum chambers. The required vacuum pressure in the ducts is 10(-6) Pa or less. Since the effective baking of such a large system is not easy in practice, we plan to adopt a TiN coating technique instead of baking, so as to reduce the outgassing rare. In order to check it, we have performed several tests for TiN-coated SUS316 ducts of 1 m in length and 150 mm in diameter. The results have allowed us to include 150 m TiN-coated ducts in our large system, which might bring a large advantage for future projects involving kilometer-scale detectors. Copyright (C) 1996 Elsevier Science Ltd.