Status report from KEK Feb. 26, 2010 T. Higo, S. Matsumoto T. Takatomi, Y. Higashi and X-band group

Contents Structure production – T24, TD24 Nextef – TD18_#2(KEK) run – Pulse compression related system expansion – KT-1 Quad #5 – Disassembly

Structure production (1) T24_Disk_#4(KEK) – All sent to SLAC on Feb. …….. TD24_Disk_#3(SLAC) & TD24_Disk_#4(KEK) – Flatness issue was solved – All parts being delivered to KEK by Feb. 22 – RF checking at KEK should be by 1 st week of March, followed by immediate shipping to SLAC Discussion of shipping – Proposed shipping from SLAC to KEK in vacuum – All parts needed for it were sent to SLAC for T24 shipping.

N 2 purged L valve (CF070) ACC Structure Properly sealed for shipping By CF070 blind Shipping configuration SLAC vac test N 2 purged L valve (CF070) ACC Structure Attach filter in clean room KEK cleanroom Go to Nextef N2N2 Pumping L valve (CF070) L valve(KF25) ACC Structure Filter Proposed shipping from SLAC to KEK

Quad #5 S ij was measured on Feb. 22. Relative movement among four rods were checked with FARO Fusion. Pipes and H-bend arms were removed. Relative movement among four rods were checked with CMM ZEISS. S ij will be measured on Feb. 26. Optical inspections will be made. Bead pull will be made soon. Disassembling will be in March. ………………

Alignment check of quad #5 after high power test Results With H-bend and cooling pipe FARO: reproducibility < Transverse: < Longitudinal : < After removing H-bends and cooling pipes CMM ZEISS: reproducibility ~micron Transverse: < Longitudinal : <

Nextef (1) TD18_Disk_#3(KEK) – Dark current has been continuously reducing. – Above ~80MV/m, most of breakdowns are associated with a reflection from left-side load assembly by several percent power. – Consistent to what Steffen speculated from the reflection pulse analysis. – Further processing will be done. Pulse compression related system expansion – All component drawing are done – Started fabrication for all, all machining will be done by end of March – Brazing will be ending in April~May, done in KEK – May start with single mode PC, 150ns compressed pulse, then to 300ns. KT1~Shield-B – Most of the key components, (bend, mode convertor, vac pumping port), are under fabrication in parallel to those for PC described above. Activities in new JFY – Should make a practical plan through discussion with CERN and SLAC

Nextef (2) KEK-load tested at KT-1 – Two KEK-made loads, called “Ohtsuka load” were tested up to klystron limit. Both worked well up to such as 40MW, 500ns and 55MW, 200ns. Operation of Nextef and KT-1 – We sacrificed KT-1 to stop for a few weeks due to shortage of the INV power supply. – We prioritize Nextef operation to continuously run it. Visitor from Tsinghua – May not come due to health problem. – System hard wares and softwares are still need to be developed.

Event with reflection from left-load arm near KLY ACC-Structure Load(L) arm Load(R) arm Triggered by reflection from downstream and accompanied by current burst into beam pipe F Rs Ra T

Eacc=sqrt[Pin(MW)/62.7(MW)]*100(MV/m)

Es=2.0*Eacc; slope= 6.53e3*phi^1.5/beta/Es(MV/m); Beta = 62751/1486=42.2  =42  =57  =72  =70

Deduction of the field enhancement factor  (Cu)=4.52eV Assuming Es/Eacc=2 actually T18_VG2.4_Disk Es/ ~2.62 max Fitting of modified F-N curve SLAC Workshop T.Higo Note that today’s (Shuji’s) beta value were deduced assuming Es/Ea=2, which makes beta larger than the formula here by 1.3. This reminds me necessity of considering the beta value deduction. (Higo)

Dark current evolution Dark current has been decreasing by two order of magnitude in these two months. Beta value has been steady decreasing from 70 to 40, assuming Es/Eacc=2. It seems interesting to check Es*beta etc. Note that the beta values shown till today on T18and Quad, are based on Es/Eacc=2.62.

X-band related budget for JFY2009 (Spare slide for US-Japan application for JFY201 on March 2) 2 March 2010 日米・継続・肥後 18 KEK Structure fabrication Infrastructure & Nextef CERN financially supports for Structure fabrication High power test System expansion SLAC conducts Structure fabrication High power test Basic research US-Japan 6.5M\ Used mostly for basic research fund CERN/KEK collaboration 31M\ KEK budget 16M\ CLIC US-HG Very big and essential contribution to KEK’s work!

Conclusion We continue TD18 high gradient processing with replacing left-arm load assembly. We restarted investigation of Quad #5. Most of essential components, both for PC-related and single-klystron-based systems, are under fabrication now. All parts for TD24 are now at KEK, preparing to ship to SLAC. We greatly appreciate the efforts from CERN and SLAC for our work. We will make a plan for next JFY soon and propose it to discuss among three laboratories to actually make our action plan.