Improvement of the magnet-power supplies on J-PARC MR

Abstract

Commissioning of Japan Proton Accelerator Research Complex (J-PARC) main ring (MR) was started on May 2008. Very large magnetic fieldripples of the order of 10^－2 were foundin the dipole, the quadrupole andthe sextupole magnets in the MR. In order to reduce the ripples, we modified the magnet-power supplies, which includes removal of the 600 Hz trap filter, addition of another DCCT to subtract the common mode signal and symmetrization of the cabling to all the magnets. The modification achieved the magnetic field ripples of the order of 10^－3 during the injection and 10^－4 during the extraction. We have succeeded in accelerating of the protons up to 30 GeV, which were extracted to the hadron experimental hall and the neutrino beam line.