Conceptual design of a bipolar kicker magnet for the J-PARC-Kamioka Neutrino Project

The Japanese Hadron Facility (J-PARC) includes a ring in which the beam is accelerated from an energy of 3 GeV to 50 GeV. One of the proposed experiments, which require the beam to be extracted from this ring, is a long baseline neutrino oscillation experiment. Space constraints in the lattice of the ring result in a requirement for a novel bipolar combined function kicker that can be used for fast extraction or abort. Magnetic field pulses with a rise time of approximately 1.1μs and 4.3μs flat top duration are required. One of the stringent design requirements of the extraction system is a flat top ripple of less than ±1%. The proposed kicker system is composed of 6 kicker magnets of 1.5 m length each, powered by pulse forming lines (PFL´s). To achieve the required kick angle of ±5.32 mrad a low characteristic impedance has been chosen. This paper discusses several different concepts for the kicker system and presents the results of investigations into options for system impedance, and kicker magnet type including transmission line, lumped inductance and hybrid-transmission line.