X-band PPM klystron development for JLC

摘要

In this paper, we summarize the status of X-band PPM klystrondevelopment for the Japan Linear Collider (JLC) project. The periodicpermanent magnet (PPM) klystrons are under development in thetwo-stage/two-year project with Toshiba. The goal is to produce 50 MWoutput power with efficiency >50% at 1.5 μs pulse length at thefirst klystron and then to advance to 75 MW with efficiency =55% at thesecond one. The first PPM klystron has been tested, and it achieved 56MW power with 50% efficiency at the standard 1.5 μs pulse length.Neither oscillation of the parasitic mode nor gun oscillations wereobserved. The particle transmission was found to be 100% when no RFsignal is applied. The second PPM klystron is currently under high-powertesting. It has improved water cooling system of a PPM circuit and theoutput cavity for 150 Hz operation. The RF system was also revised for ahigher efficiency. To date (June 6, 2001), the PPM-2 klystron produced73.2 MW at 1.4 μs pulse length and 70 MW at 1.5 μs pulse lengthwith the efficiency of 54.5%. The maximum efficiency reached 56% at thespecified cathode voltage. The high-power testing will be continued toattain a 75 MW output power with a standard 1.5 μs pulse. Details ofthese developments and measurement results are presented