포항가속기 저장링챔버의 헬륨누설검사 = Helium Leak Test for the PLS Storage Ring Chamber

국문 초록 (Abstract)

포항가속기 저장링 진공챔버는 진공도가 10(-10)Torr로 유지될 수 있도록 설계되었고, 초고진공에 적합하도록 TIG용접을 하여 헬륨에 대한 누설률이 1×10(-10)Torr·ℓ/sec 이하의 기밀성이 요구되고 있다. 저장링 진공챔버에 적용된 TIG용접방법과 결함에 대해 논하고 누설검사에 사용된 헬륨누설검사기의 원리 및 검사방법에 대해서 보고자 한다.

다국어 초록 (Multilingual Abstract)

The storage ring vacuum system for the Pohang Light Source (PLS) has been designed to maintain the vacuum pressure of 10(-10) Torr which requires UHV welding to have helium leak rate less than 1×10(-10) Torr·ℓ/sec. In order to develop new technique (PLS) welding technique), a prototype vacuum chamber has been welded by using Tungsten Inert Gas welding method and all the welded joints have been tested with a non-destructive method, so called helium leak detection, to investigate the vacuum tightness of the weld joints. The test was performed with a detection limit of 1×10(-10) Torr·ℓ/sec for helium and no detectable leaks were found for all the welded joints. Thus, the performance of welding technique is proven to meet the criteria of helium leak rate required in the PLS Storage Ring. Both the principle and the procedure for the helium leak detection are also discussed.