KEKB INJECTOR LINAC AND UPGRADE FOR SUPERKEKB

KEKB INJECTOR LINAC AND UPGRADE FOR SUPERKEKB S. Michizono for the KEK electron/positron Injector Linac and the Linac Commissioning Group KEK KEKB injector linac Brief history of the KEK electron linac Continuous injection (CI) scheme Maintenance and R&D at CI scheme Upgrade for SuperKEKB Schematic ------MOP31 S.Ohsawa et al. Rf source ------ (rf window) THP58 S. Michizono et al. SKIP ------THP61 T.Sugimura et al. Acceleration structure ------THP29 T.Kamitani et al. Dummy load Summary Linac Conference 2004 (Aug.,18,2004) 1/32

Superconduct ing cavities (HER) Each length: KEKB B-Factory e- ARES copper cavities (HER) 3018 m e+ Belle detector KEKB schematic ARES copper cavities (LER) 8 GeV e- ->HER 3.5 GeV e+ ->LER TRISTAN tunnel e+ target Linac Conference 2004 (Aug.,18,2004) 2/32

Operation Statistics PF PF PF/ AR run TRISTAN TRISTAN- AR KEKB const KEKB 2.5GeVe- e+ 8GeVe- / 3.5GeVe+ 8,000 6,000 4,000 2,000 0 8 6 4 2 0 (1) operation time (hour) (2 ) failure (%) 40 30 (3) hum an resources 20 10 0 year 78 80 82 84 86 88 90 92 94 96 98 00 02 Linac Conference 2004 (Aug.,18,2004) 3/32

100,000 hours operation since 1982 Many of them are still working for accelerator physics! Linac Conference 2004 (Aug.,18,2004) 4/32

Operation status Total operation time reached 100,000 hours on March,2003. Machine failure is limited less than 5 %. Linac Conference 2004 (Aug.,18,2004) 5/32

Continuous Injection (CI) Scheme traditional CI since Jan.,2004 Effective luminosity increases ~20% Linac Conference 2004 (Aug.,18,2004) 6/32

Beam on time after CI scheme Careful beam tuning and short maintenance are required at CI. KEKB CI Linac Conference 2004 (Aug.,18,2004) 7/32

Dip test In order to find out the emission decrease of the klystrons, dip tests are applied to all the klystrons. Deeper dip -> operation near the shoulder. heater off time: 60 sec. Total measurements: within 10 min. Example of emission decrease 2.00 micro-perviance 1.95 1.90 1.85 Sep.,2003 Dec.,2003 Mar.,2004 May,2004 1.80 0 100 200 300 400 500 Time [sec.] Linac Conference 2004 (Aug.,18,2004) 8/32

Dip test Periodical measurements of the dip -> find out the emission decrease with time D ip tests at klystron gallery 16 14 03/09 12 KLY rem oval 03/12 K LY rem oval % 10 8 6 04/03 04/05 4 2 0 A1 A2 A3 A4 B1 B2 B3 B4 B5 B6 B7 B8 C1 C2 C3 C4 C5 C6 C7 C8 11 12 13 14 15 16 17 18 Klystron gallery unit Linac Conference 2004 (Aug.,18,2004) 9/32

Energy spread feedback Feedback systems Energy feedback -> done Position feedback -> done Energy spread feedback -> tested with 8 electrodes BPM Linac Conference 2004 (Aug.,18,2004) 10/32

KEKB INJECTOR LINAC AND UPGRADE FOR SUPERKEKB S. Michizono for the KEK electron/positron Injector Linac and the Linac Commissioning Group KEK KEKB injector linac Brief history of the KEK electron linac Continuous injection (CI) scheme Maintenance and R&D at CI scheme Upgrade for SuperKEKB Schematic Rf source SKIP Acceleration structure Dummy load Summary Linac Conference 2004 (Aug.,18,2004) 11/32

Schematic of SuperKEKB 8 GeV positron 4.1 A New collision point design 3.5 GeV electron 9.6 A Energy exchange: e-: 8 GeV -> 3.5 GeV e+; 3.5 GeV -> 8 GeV Linac Conference 2004 (Aug.,18,2004) 12/32

Upgrade of the injector linac 8 GeV e- / 3.5 GeV e+ 8 GeV e+ / 3.5GeV e- Two-bunch operation kicker ~80 m S-band (2856 MHz) C-band(5712 MHz) (#3 ~ #5 sectors) Linac Conference 2004 (Aug.,18,2004) 13/32

Linac Accelerator module (From S-band To C-band) MOP31 S.Ohsawa et al. Present S-band accelerator module New C-band accelerator module Wave guide Pulse Modulator S-band SLED 41 MW 4 µs S-band Klystron Wave guide 40 MW 2 µs C-band compressor Pulse Modulator C-band Klystron Wave guide C-band compressor Pulse Modulator C-band Klystron 40 MW 2 µs S-band accelerating sections C-band accelerating sections Accel. field gradient = 21 MV/m Accel. field gradient = 42 MV/m Linac Conference 2004 (Aug.,18,2004) 14/32

Overview of C-band rf system C-band rf system from #3 to #5 sector Forty eight klystrons are installed (instead of 24 S-band klystrons) RFSystem Diagram C-band Plan(example) 10kW AMP. e- 100m 114 MHz SHB1 ElectronGun 100m 571 MHz SHB2 High Power ATT/Phase Shifter 1kW Amp. System Trigger System 20m MR Prebuncher Buncher ACC Guide SB-A 10 MHz 508 MHz 40m 5m SectorA Counter CW 571 MHz 5m SB-B Ref. Signal Generator 114 MHz (FMD-30) Coaxial Lines 30m 80m Sector B MAINDRIVE LINE SB-C 571 MHz SB-1 2856MHz 30m Optical Lines 15m E/O 1kW Amp. System O/E Driver 60kW S-band Klystron SUB DRIVELINE(39D) IΦA C-band Waveguide Driving Line SUB-BOOSTER 2 50MW S-band Klystron SLED IΦA SUB-BOOSTER3-1 100kWC-band Klystron SUB DRIVE LINE(WG) 50MC-band Klystron Target ACC ACC Sector C Sector 1 e+ e- Sector 2 Sector 3-1 Sector 3-2 Sector 4-1 Sector4-2 Sector 5-1 Sector 5-2 5712MHz SLED Linac Conference 2004 (Aug.,18,2004) 15/32 SB3-2 SB4-1 SB4-2 SB5-1 SB5-2 48 C-band klystrons

KEKB INJECTOR LINAC AND UPGRADE FOR SUPERKEKB S. Michizono for the KEK electron/positron Injector Linac and the Linac Commissioning Group KEK KEKB injector linac Brief history of the KEK electron linac Continuous injection (CI) scheme Maintenance and R&D at CI scheme Upgrade for SuperKEKB Schematic Rf source (LLRF, Modulator, high-power klystron, rf window) SKIP Acceleration structure Dummy load Summary Linac Conference 2004 (Aug.,18,2004) 16/32

Driver klystron Retune the existing C-band 200 kw klystron for weather observation station (MELCO). Driver klystron (SB) can deliver >100 kw (35 kv). Same modulator and HV supply to S-band system is used. Klystron and magnet 250 200 42.6kV m ag:22.3a/22.3a/22.3a 35kV m ag:17.0a/17.0a/17.5a 27kV m ag 15.6A/16.8A/11.7A SBK modulator P out[kw ] 150 100 300 250 200 Pin=0.16W mag:22.3a /22.3A /22.3A 50 P out[kw ] 150 100 0 0.01 0.1 1 10 Pin[W ] 50 0 20 30 40 50 Linac Conference 2004 (Aug.,18,2004) 17/32 V[kV]

Compact modulator By using invertor P.S., the modulator size can be 1/3 (4.7 m->1.8 m). Present PFN and Thyratron are reused at new modulator. Present modulator Compact modulator Thyratron Linac Conference 2004 (Aug.,18,2004) 18/32

C-band klystron C-band 50 MW klystron is commercially available. (developed by KEK for linear collider) Y. Ohkubo, H. Yonezawa, T. Shintake, H. Matsumoto and N. Akasaka, HighTHE C-BAND 50MW KLYSTRON USING TRAVELING-WAVE OUTPUT STRUCTURE, Linac98, Chicago, p.932. Linac Conference 2004 (Aug.,18,2004) 19/32

R&D of c-band rf window Requirements: 50 MW 2 µs ( S-band 50 MW 4 µs) About Sixty S-band rf windows are successfully operated in KEKB linac. (MTBF > 40,000 h.) Electric fileds should be less than rf windows used in S-band linac. Mix-mode window (TE11+TM11) enables to lower the edge electric field. Electric field at center of the ceramics [MV/m@50MW] Electric field at edge of the ceramics [MV/m@50MW] Maximum electric field on the ceramics [MV/m@50MW] S-band C-band 3.7 3.1 1.7 0.8 5.5 3.7 Band width [MHz](VSWR<1.2) 600 210 VSWR 1.4 1.35 1.3 1.25 1.2 1.15 1.1 1.05 1 210M Hz 5.6 5.65 5.7 5.75 5.8 5.85 frequency [GHz] THP58 S. Michizono et al. Linac Conference 2004 (Aug.,18,2004) 20/32

Mix-mode rf window 4-Rc1/8 ネジ 4-1/4"SWL FLANGE- MALE FLANGE- FEMALE ( 78. 05) ( 148. 4) ( 78. 05) 304.5 THP58 S. Michizono et al. Linac Conference 2004 (Aug.,18,2004) 21/32

Resonant ring in the shield High power tests of the window was carried out by resonant ring. Rough tuning: spacer Fine tuning: operation frequency (5712->5710.2 MHz) RF window THP58 S. Michizono et al. Linac Conference 2004 (Aug.,18,2004) 22/32

Results at resonant ring Maximum operation power of 300 MW (2μs), corresponding to 6-times larger than specification (50 MW). Only 3-times rf trips during 8 hours operation at 300 MW. Rf power (300 MW) THP58 S. Michizono et al. Linac Conference 2004 (Aug.,18,2004) 23/32

SKIP (SuperKEKB Injector Pulse compressor) Mode: TE015(SLED)-> TE038(LIPS) Similar cavity size to present S-band SLED. Higher Q value. Output 200 MW @43 MW input Power magnification:4.7 (lower than calculated value(5.5) due to slower switching time) THP61 T.Sugimura et al. Q 0 =13200 coupling β = 6.6 Linac Conference 2004 (Aug.,18,2004) 24/32

KEKB INJECTOR LINAC AND UPGRADE FOR SUPERKEKB S. Michizono for the KEK electron/positron Injector Linac and the Linac Commissioning Group KEK KEKB injector linac Brief history of the KEK electron linac Continuous injection (CI) scheme Maintenance and R&D at CI scheme Upgrade for SuperKEKB Schematic Rf source (LLRF, Modulator, high-power klystron, rf window) SKIP Acceleration structure Dummy load Summary Linac Conference 2004 (Aug.,18,2004) 25/32

C-band accel. section (First prototype) 54 regular cells 1m-long iris diameter 2a: 12.44 ~ 10.41 mm Based on present S-band acceleration structure THP29 T.Kamitani et al. Filling Time t F = 234 nsec Linac Conference 2004 (Aug.,18,2004) 26/32

C-band accel. section installed in KEKB linac (2003 September) S-band section C-band section THP29 T.Kamitani et al. Linac Conference 2004 (Aug.,18,2004) 27/32

Beam acceleration study Energy gain measured by changing acceleration phase with 43.8 MW x 0.5 µs RF pulse ~80 MV THP29 T.Kamitani et al. Linac Conference 2004 (Aug.,18,2004) 28/32

Inside of the acceleration structure Discharge every 10 min. even after conditioning. It took place around input coupler (rf wave analysis). Discharge traces observed input coupler and first disk. output input THP29 T.Kamitani et al. Discharge location analyzed by rf waves. Coupler from inside Coupler iris from outside First disk (2a) Linac Conference 2004 (Aug.,18,2004) 29/32

Second acceleration structure Thicker iris Wider coupler length @ 2 nd acceleration structure High power test @ Aug.,2004. 1 st coupler 2 nd coupler THP29 T.Kamitani et al. Linac Conference 2004 (Aug.,18,2004) 30/32

Dummy load Newly designed 2kW Matsumoto-type dummy load 26 SiC cylinders SiC diameter 12 mm High power test OK up to 2 kw (100 MW peak) heat distribution (norm alized by peak) 1.5 1 0.5 Heat distribution C -band dummy load heat distribution dum m y N o.1 dum m y N o.3 design value 0 0 50 100 150 250 300 350 400 450 Linac Conference 2004 (Aug.,18,2004) 31/32 distance from a bottom (mm)

Summary S-band linac has been operated > 100,000 hours. The failure rate is about 5% and it contributes to the stable KEKB operation. C-band R & D is in progress. High power test of the prototype C-band accelerator module has been performed since October 2003. Most of the components are working well. (Remaining issues) Breakdown at input coupler -> improve @ 2 nd acc. structure inverter P.S. troubles -> long term operation (related presentations tomorrow) Rf window : THP58 S. Michizono et al. SKIP: THP61 T.Sugimura et al. Acc. structure THP29 T.Kamitani et al. Linac Conference 2004 (Aug.,18,2004) 32/32