Heat leak measurements and thermal modeling of a mechanical support for a SSC beam tube liner

Hydrogen desorbed from the beam tube of the super collider by synchrotron radiation may adversely affect the luminosity lifetime of the proton beam. One solution to this problem is to place a distributed cryopump within the beam tube which will trap desorbed gasses. Such a cryopump can be effected by attaching cryosorber to the cold (4 K) magnet bore tube. A concentric tube, or liner, centered within the magnet bore tube shields the cryosorber from the synchrotron radiation, and becomes the beam tube. By perforating a fraction of the liner surface with small (on the order of 1-3 mm) holes, the liner/cryosorber assembly becomes a distributed pump. The liner temperature may be allowed to equilibrate at a temperature close to that of the 4 K bore tube. However, actively stationing the liner at 80 K is of interest because the synchrotron radiation heat can then be deposited in the liquid nitrogen system. This, at least partially, decouples the allowable beam current from the helium cryogenic system. Active control is accomplished by means of 80 K helium flowing through a trace tube attached to the outside of the liner. A cross section of the magnet bore tube with an 80 K liner is shown