AVS 46th International Symposium
    Vacuum Technology Division Thursday Sessions
       Session VT-ThM

Paper VT-ThM5
Measuring and Locating Internal Helium Leaks in the RHIC Insulating Vacuum System

Thursday, October 28, 1999, 9:40 am, Room 610

Session: Outgassing, Leaks, and Mass Flow Controllers
Presenter: H.C. Hseuh, Brookhaven National Laboratory
Authors: R. Davis, Brookhaven National Laboratory
C. De La Parra, Brookhaven National Laboratory
H.C. Hseuh, Brookhaven National Laboratory
P. Mickaliger, Brookhaven National Laboratory
D.J. Pate, Brookhaven National Laboratory
Correspondent: Click to Email
The Relativistic Heavy Ion Collider (RHIC) uses superconducting magnets to bend and focus the high-energy particle beams. Strings of these magnets are enclosed in insulating vacuum cryostats up to 480 meters long. The cryostat vacuum must be 10@super -5@ Torr or less to minimize heat transfer from the ambient cryostat wall to the 4K magnet cold mass. There are over 25,000 in-situ welds of internal helium lines with a total weld length over 7 km. Helium leaks greater than 10@super -5@ std.cc/sec (ambient leak rate) in these welds were located and repaired. The methods of locating these leaks in the long cryostat volumes will be described. Smaller leaks were monitored during the cool down of the magnets. The correlation of the leak rates with the helium line temperature and pressure will be presented.