Fast-extraction kicker-magnet system from the KEK-PS main ring

A fast extraction kicker-magnet system from KEK-PS main ring has been developed for a neutrino-oscillation experiment. The kicker system comprises a Blumlein system (which includes a thyratron housing, a HV-DC power supply, two PFN cables (12.5 Ω, 130 m) and a matching resistor with diodes), a pulse transformer, two transmission cables and a twin-distributed-type kicker magnet. The height and width of the kicker magnet aperture is 55 mm and 110 mm, respectively. The effective magnet length is 300 mm. When the PFN is added with 80 kV, the system can produce a magnetic field of 0.14 T with a flat top of 1 μs and a rise time of 260 ns. Although the magnetic strength is sufficient, the rise time is too long to match the desired value of 155 ns. The main part of the long rise time comes from the deterioration of the current transmission through PFN cables and current rise time from the thyratron housing with the floating inductance. We are improving them in order to decrease the current rise time. (author)