Status of X-Band PPM Klystron R&D for JLC KEK Yong Ho Chin ISG9 KEK December 10-13, 2002

Status of PPM-3 Status of PPM-3 KEK PPM-3 klystron (JFY2001) Goal:  60% efficiency by installing two 2nd-harmonic cavities.  Revision of water cooling system at the penultimate cavity area. High power testing started in March A feedback system was also installed at the testing set-up to speed up the conditioning process. Observations  The efficiency is slightly lower than PPM-2. 2nd-harmonic cavities suspected.  The Kazakov windows-3 show far better performance than the previous ones. Almost no light emission at 60MW. Very fast conditioning at long pulse.  The improved water cooling system helps to reduce the temperature rise in the penultimate cavity region. Below 30 degree rise at 100Hz operation.

Just after ISG8 in June, PPM-3 achieved Output power65MW Output power65MW Pulse length1.5  s Pulse length1.5  s Efficiency53% Efficiency53% Repetition rate50Hz Repetition rate50Hz However, we suffered from one problem after another since then… Modulator power supply failed in June Pulse transformer broke down in June RF discharge in the load dragged the conditioning out through the fall  BINP load started to degrade and the stable operation became difficult to maintain due to the reflected power from the load.  After exchange to the “dry loads”, a right window broke down, seemingly by a too high voltage at the window due to the reflected power from the loads.  We did monitor the reflected power from the load, but did not feed back it to the input power to TWT.

Status of Other PPMs Remodeled PPM-2 PPM-2 has shown the best performance so far. To explore its performance, PPM-2 was remodeled with  Kazakov-3 windows (= PPM-3)  Improved water cooling system (=PPM-3)  Retuned output cavity (=PPM-3) PPM-2 was shipped to SLAC for further testing and will be installed to NLCTA if available. KEK PPM-4 (JFY2002) Temporarily cease the quest for higher efficiency at 56% and direct efforts to high repetition rate. Combination of the RF design of PPM-2 and the mechanical design of PPM-3.  No 2nd-harmonic cavity  Further improved water cooling system  Kazakov window-3  Stick to the integrated PPM stacking It is schedule to be delivered to KEK in early January 2003.

Other Activities Loads We need new robust loads to test PPM-4 at KEK  Two rectangular loads are expected from SLAC soon (in December or early January?)  Two TE01 loads available at Toshiba (left-over from SLAC 50MW PPM). Two mode-converters (HP) are being built for the new Kazakov TE01- window. We need just tapers to connect them. New TE01-window Just for the case that more robust windows are needed, we are developing a new TE01-window.  Kazakov’s talk High power testing facility in the AR south For testing of structures and other RF components, we are investigating a possibility to upgrade the existing but unused high power testing facility in the AR south to produce pulses with  MW output power  400ns pulse length  25-50Hz rep. rate

Items to be discussed When will SLAC loads arrive at KEK? Their performance A possibility to buy two more in next FY How long and how much should we test PPM-4 at KEK before shipping it to SLAC? 3 months? Till 75MW, 1.6  s, and 50Hz achieved? Precise plan and schedule of PPM-2 and PPM-4 testing at SLAC. February (PPM-2) and June (PPM-4). Check the preparation status for PPM-2 PPM-2 and its all magnets (PPM and electric) were shipped to SLAC already. Main lead shield will be shipped in December. The rest (small stuffs) will follow as well. Check the plan, schedule and preparation status for installation of PPM-2 and 4 to NLCTA. Set up milestones for 2003 and Contingency and back-up plan Marc says that “do not worry” January till the end of April SLAC TE01 window spare KEK TE01 window spare Test At SLAC New date