High power rf tests on input couplers for 972 MHz superconducting cavities in the J-PARC project

Prototype coaxial input couplers with a planar rf window and a high power test stand were designed and fabricated. The high power tests with a 972 MHz pulsed klystron had been successfully carried out. Input rf power of 2.2 MW in a pulsed operation of 0.6 msec and 25 Hz (370 kW in 3.0 msec and 25 Hz) was transferred to the input couplers without any problem.