STRUCTURE OF VACUUM SEAL

摘要

PROBLEM TO BE SOLVED: To obtain a structure of vacuum seal which can avoid the fracture due to the application of the stress such as shearing stress on a connection of the vacuum seal and keep the vacuum maintenance at a high level by providing seal-end flange parts on the lid and body sides and a connecting seal part. SOLUTION: A vacuum seal is formed by butt-welding a ringed seal (connection seal part) 22 to seal end flange parts 20 and 21 installed projectingly from a body-side flange 8 and a lid-side flange 9 respectively. Consequently, even if slight displacement occurs between the body-side flange 8 and the lid-side flange 9, the ringed seal 22 absorbs the stress by deforming itself to prevent the fracture causing the vacuum leakage in welds 23 and 24. This makes it possible to keep the vacuum maintenance in a cryostat at a high level.