Leak checking in ISABELLE
The Intersecting Storage Accelerator (ISABELLE) contains two completely independent vacuum systems. One known as Beam Vacuum operates at 1 x 10/sup -11/ Torr and maintains a very clean environment for the circulating proton beam. The other system known as Insulating Vacuum maintains superconducting magnet vessels at a pressure below 1 x 10/sup -6/ Torr. In this system all gasses except helium are cryocondensed on the cold surfaces of superconducting magnets and cryogenic circuits. Turbomolecular pumps pump the inadvertent small helium leaks. The helium background both in the MagCOOL area and in the ISABELLE tunnel limits the sensitivity of conventional leak detectors. Leak detection in ISABELLE is one of the most important functions, since there are thousands of bellows and welds operating at 4 K and at 15 atmosphere pressure and that many welds can only be leak checked at room temperature. Leak rates are known to increase by 4 orders of magnitude when cooled from 300 K to 4 K. Thus the required 10/sup -10/ Torr liters s/sup -1/ sensitivity is essential for proper operation and methods and equipment which permit the location of such leaks in large systems have been developed and tested on the First Cell and the refrigerators. They produced a completely leak free system, i.e. the helium background did not change when all pumps were closed for 24 hours. These methods and the equipment are discussed in detail.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6553752
- Report Number(s):
- BNL-29148; CONF-810314-92; TRN: 81-006793
- Resource Relation:
- Conference: Particle accelerator conference, Washington, DC, USA, 11 Mar 1981
- Country of Publication:
- United States
- Language:
- English
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