Superconducting Cavities for Super KEKB S Mitsunobu Summary
Superconducting Cavities for Super. KEKB S. Mitsunobu
Summary of KEKB SCC Operation Max. Current 1270mA n Max. Power for Beam 380kW n HOM Power 14kW n Operation Voltage 1.4-2.0 MV n Average Trip rate is once per month for good vacuum condition. . n
KEKB SC Super-KEKB SC Cavity Field 1. 4 -2. 0 MV OK n Input Coupler 380 kw 460 k. W OK(500 k. W) n Input Coupler Qext 7 x 104 5 x 104 n HOM Power 10 k. W 60 k. W (test 43 k. W) n Large Gate Valve D=220 mm to be solved n Add 4 Cavities n Larger Sigma z should be studied n
Dedicated 1 MW klystron system for coupler test bench Testing high power coupler, at D 10 area new 1 MW klystron power supply and klystron system have been constructed. One of limitation of high power operation for KEKB coupler is heating at capacitor for bias voltage. An air duct is added near this capacitor to increase cooling power. Couplers could operate more than 500 k. W.
Cap of Doorknob Air Duct
HOM Damper Cooling limit (4. 0 m/sec ) 60 k. W n Inner Surface Temperature Limit 200 ℃ n KEKB 80 kw with 4 A at 3 mm BL(2. 5 p. C) n D=220 mm Beam Pipe 56 k. W(4 A, 3 mm) n KWKB could be operate (4 A, 4 MM, 1. 8 p. C) P=k(σz)・I**2/frev/Nb n
A SBP HOM damper have been tested up to 18 k. W and 25 k. W for LBP HOM damper.
Acoustic monitor attached
Artificial acoustic signal breaking pencil lead of 0. 5 mm
Crab cavity Crab cavities will be install in KEKB ring next winter shutdown. n New crab cavity design for SKEKB have been proposed by Akai. n
New crab cavity (Coaxial type) n n (Left) The cross-shaped waveguide dampers and coaxial dampers are attached at the squashed-cell. (Right) Cross section of the coaxial damper at the cut plane of Y-Y’. Proposed by Akai
Summary n n KEKB SC will be used with small modification for Super-KEKB. Coupler already tested more than 500 k. W(800 k. W in short time), beam test will be done. HOM damper is most important issue for Super. KEKB SC. (43 k. W reached) Crab cavities going to be test soon.
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