Status of X-Band PPM Klystron R&D for JLC

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

2. 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 2002. • 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.

3. Just after ISG8 in June, PPM-3 achieved • Output power 65MW • Pulse length 1.5ms • Efficiency 53% • Repetition rate 50Hz • 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 2002. • 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.

4. 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.

5. 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 • 50-100MW output power • 400ns pulse length • 25-50Hz rep. rate

6. 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 ms, 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 2004. • Contingency and back-up plan Marc says that “do not worry” January till the end of April New date SLAC TE01 window spare Test At SLAC KEK TE01 window spare