Cryogenic adsorption of noncondensibles in the high‐vacuum regime

Abstract

Cryogenic vacuum pumps must use cryogenic adsorption means to remove helium, hydrogen, and neon from vacuum systems in order to achieve high vacuum. The capacity of one such cryosorbent, charcoal, is presented in the form of isosteres of hydrogen and helium in the pressure range 10−7–10−4 Torr and temperature range 10–25 K. Certain important dynamic loading effects related to surface mobility and pore clogging are discussed which can, in high‐flow environments, appreciably affect the apparent capacity of the adsorbent. The implications of the static and dynamic results are discussed in relation to practical aspects of cryopumping, i.e., partial or selective regeneration and optimal cryopumping temperatures.