HIGH POWER TEST OF THE COMPACT, OIL-FILLED MODULATOR FOR THE C-BAND KLYSTRON

We propose a new concept of pulsed modulator. The modulator supplies 114 MW peak power at 60 pps maximum repetition rate. The modulator is housed in a commercial stainless steel tank. The physical size is only 1.5 m wide, 1.0 m high and 1.0 m depth. All the high voltage components are immersed in insulating oil. Superior insulating performance of the oil enables the modulator to be compact and reliable in long-term operation. Since the stainless steel tank provides an ideal electric-shielding boundary like Faraday-cage, the modulator is very “quiet” and stable. The first model was constructed in March 2003. We obtained the expected performances; PFN charging voltage up to 45 kV, and -22 kV pulsed (4.5 µsec FWHM) output voltage at 60 pps repetition rate. It drives the 50 MW C-band (5712 MHz) klystron at -350 kV beam voltage through a 1:16 step-up transformer. The repeatability of pulsed voltage are better than 0.5% within 2.5 µsec flat-top.