Cryopump and cyropanel having a frost concentrating device

摘要

In a cryopump (10) a frost concentrating device (26) is affixed to a condensing cryopanel (34) and provides surfaces (32) for condensing gases which are cryopumped through an opening (152) in the vacuum vessel. The surfaces (32) of the frost concentrator (26) extend towards the opening (152) in the vacuum vessel and thus limit the amount of gases which condense on the surfaces (22) of the condensing cryopanel facing the opening. The result is that the gap between the radiation shield (18) and the condensing cryopanel (34) does not become significantly narrowed by condensing gases, particularly in the area closest to the opening through which gases are cryopumped. This allows other gases to pass easily through the gap and condense on surfaces (22) of the condensing cryopanel (34) further away from the opening (152) of the cryopump (10) or to be adsorbed by an adsorbent material shielded by the condensing cryopanel (34).