摘要 |
<p>A cryopump includes a two-stage refrigerator, a primary pumping surface, and a radiation shield. The radiation shield is in thermal contact with the first stage of the refrigerator. The primary pumping surface is surrounded by the radiation shield and is in thermal contact, through a direct conductive link, with the second stage of the refrigerator. The refrigerator, however, is external to the radiation shield.</p> |