AVS 52nd International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuP

Paper VT-TuP14
Photon Stimulated Desorption (PSD) and Secondary Electron Measurements of a Titanium Nitride Coated Copper Beam Chamber for the KEKB Collider@footnote 1@

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Vacuum Technology Poster Session
Presenter: C.L. Foerster, Brookhaven National Laboratory
Authors: C.L. Foerster, Brookhaven National Laboratory
C. Lanni, Brookhaven National Laboratory
K. Kanazawa, High Energy Accelerator Research Organization, Japan
Correspondent: Click to Email
KEKB is an asymmetrical collider operated by the High Energy Accelerator Research Organization (KEK) in Ibaraki, Japan. The collider utilizes two UHV ring chambers, one for a 3.5 GeV positron beam and the other for an 8 GeV electron beam, to study B-mesons. An electron cloud instability occurs at high currents which limits high current operation and reduces beam luminosity. To study a possible solution, which would reduce or eliminate the electron cloud, the inner surface of a one (1) meter long sample KEKB copper beam chamber was titanium nitride coated and studied on beamline U9a at the National Synchrotron Light Source (NSLS). The sample chamber has a circular cross section of 94mm inner diameter. The sample was installed in the U9a beam line and exposed to approximately 2.3X10@super+23@ photons directly from the source at a critical energy of 595 eV, striking the sample at an incident angle of 100mrad. Next, the TiN surface of the sample chamber was Argon Glow Discharge conditioned with approximately 2X10@super+18@ ions per square centimeter. After the conditioning the photon exposure was re-started and the measurements continued. The major PSD yields for hydrogen, carbon monoxide, carbon dioxide, methane, water vapor and photo-electron production are reported as a function of accumulated photon flux and sample preparation. The results are compared with previous PSD measurements on NSLS beam lines and those of other laboratories published for copper and TiN coated copper. @FootnoteText@ @footnote 1@ Work performed under auspices of the U.S. Department of Energy, under contract DE-AC02-98CH10886.