The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 26, 1991
Filed:
Jan. 25, 1990
Philip A Lessard, Boxboro, MA (US);
Thomas Dunn, Avon, MA (US);
Helix Technology Corporation, Waltham, MA (US);
Abstract
A cryopump having at least two temperature stages for pumping gases at their optimal temperatures. A first embodiment has a third temperature stage that is surrounded by and separated from the second temperature stage which is surrounded by and separated from the first temperature stage. Adsorbent placed on the second and third stages are operated at different temperatures to prevent gases with higher critical mobility temperatures from becoming immobilized at the entrance of pores and wells along the surface of the adsorbent. Another embodiment has at least a second stage, a temperature sensor, and a heater to maintain the second stage temperature at optimal level for the gas being pumped.