Cl. Foerster et al., PHOTON DESORPTION MEASUREMENTS OF COPPER AND COPPER PLATED BEAM TUBESFOR THE SSCL-20 TEV PROTON COLLIDER, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 12(4), 1994, pp. 1673-1677
Citations number
11
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
Relativistic protons circulating in the SSCL 20 TeV collider emit sync
hrotron radiation (10(16) photons/m/s, E(crit) = 284 eV). This radiati
on will photodesorb gases from the walls of the beam tube. The 4.2 K s
uperconducting magnet bore tubes will act as very long distributed pum
ps. Build up of cryosorbed gases could severely limit collider operati
on and may require a bore tube liner to hide cryosorbed molecules from
the photon flux and to increase the H-2 pumping capacity. To predict
collider vacuum performance, photon stimulated desorption experiments
have been running at the National Synchrotron Light Source (NSLS) at B
NL and on the VEPP2M storage ring at BINP, Novosibirsk, Russia. At the
U10B beamline of the VUV ring at NSLS, beam tube samples were exposed
to over 10(23) photons/m with E(crit) = 486 eV and incident angle = 1
2 mrad. Unbaked copper and copper plated stainless steel have been tes
ted. In addition, results have been obtained with a 1100 G dipole magn
etic field and with a 350-degrees-C vacuum bake. Results are presented
and compared with other measurements at the NSLS and at other laborat
ories.