Patent ID: 7313922

Claim:
A cryopump comprising: a refrigerator having first and second stages; a second stage cryopanel in thermal contact with the second stage of the refrigerator to condense low temperature condensing gases; a radiation shield surrounding the second stage cryopanel and in thermal contact with the first stage of the refrigerator; and a frontal cryopanel across an opening in the radiation shield serving as a cryopumping surface for higher condensing temperature gases; the cryopump having at least a 20% capture probability of hydrogen, and the second stage cryopanel comprising an array of baffles carrying an adsorbent, at least about 80% of the adsorbent having a direct line of sight to the radiation shield or to the opening in the radiation shield, and at least some of the adsorbent having a direct line of sight through the opening in the radiation shield.