Cryopump with improved second stage passageway
US5156007A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 1991 |
| Grant date | Oct 20, 1992 |
| Priority date | — |
| Expiry date | Jan 30, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S417/901
- WIPO fieldEngines, pumps, turbines
- WIPO sectorMechanical engineering
Abstract
Condensation on a cryopump second stage refrigerator cylinder is prevented by arranging a passageway between a colder second stage cylinder shield in thermal contact with the coldest section of the second stage and a warmer radiation shield in thermal contact with the warmer first stage. This arrangement produces a uniform and significant temperature differential in the passageway. The passageway is arranged so that the ratio of its length, L, to its width, W, is ideally greater than five. This ensures molecular collisions with the cold surface of the cylinder shield so that gas molecules are tightly bound to the cylinder shield. As a result, condensation on the refrigerator cylinder and resultant pressure variations are prevented.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.