Vacuum Surface Scrubbing by Proton Beam in J-PARC Main Ring

In J-PARC 50GeV synchrotron ring, large vacuum pressure rises above 10⁻³ Pa are found at 30GeV acceleration final stage of intensity over 10¹³ protons per pulse in the chambers of the in-vacuum electrostatic septum magnet for the slow-extraction(SX), magnetic septum for SX, and the kicker magnet for the fast-extraction. This pressure rise depends on beam intensity and peak-current, and can be reduced by continuous beam operations, such as scrubbing with proton beam, secondary emission electrons and other cations of remaining gasses or desorptions.
Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan