The Extraction Kicker System of the RCS in J-PARC

The kicker magnets are installed in the vacuum chamber at the extraction section of the RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex) facility. They kick the 3GeV proton beam to the extraction septum magnets followed by a downstream beam transport line. The RCS is designed to achieve the 1MW beam power with minimum loss. Therefore, the kicker is required to have a wide aperture, UHV (ultra-high vacuum) in its chamber, and uniformity of magnetic field. The wide aperture requires large exciting current and the use environment of the thyratron is very tough. Therefore aging run was found out to be needed. And the uniformity of the magnetic field was improved by changing length of the conductors. In order to achieve the UHV, we succeeded in reducing outgas from components of the magnet. In this paper, we will introduce the specification of the extraction kicker system in the RCS, and report countermeasure against the technical challenge described above.