DEVELOPMENT AND APPLICATION OF CRYOSORPTION PUMPING OF HYDROGEN AT 20 K BY MOLECULAR SIEVE ADSORBENT PANELS
Abstract
An experimental and theoretical investigation of the vacuum pumping of hydrogen by refrigerated panels consisting of Molecular Sieve 5A bonded to metallic substrates was performed in the pressure range of 10 to the -9th to 10 to the -6th power Torr. Initial sticking coefficients approximating unity were obtained with an array utilizing a shield and panel configuration, both refrigerated to 20 K. An effective, practical, initial activation procedure was developed for utilization with the shielded array wherein desorbed water vapor was cryopumped by the liuid nitrogen cooled elements surrounding the 20 K surfaces. Successive tests with a particular panel produced a progressive reduction in pumping speed. Methods were developed which resulted n partial recovery of prior pumping speed values; however, further effort is required to define precise conditions of efficient, successive activation procedures capable of maintaining the initial high sticking coefficient values. A theoretical model is presented which relates observed pumping speed results to diffusion parameters of the cryosorption pumping mechanism. Criteria are discussed for application of cryogenic arrays, utilizing cryopumping and cryosorption, as practical untrahigh vacuum pumping units.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1965
- Accession Number
- AD0455375
Entities
People
- J. R. Pitlor
- P. J. Gareis