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Pei Shilun for the SHBS team Accelerator center, IHEP May 10, 2007

Progress of the sub-harmonic bunching system (i.e. upgrading progress of BEPCII present bunching system). Pei Shilun for the SHBS team Accelerator center, IHEP May 10, 2007. Outline. Beam dynamics simulation and mechanical layout Design and study of the two sub-harmonic bunching cavities

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Pei Shilun for the SHBS team Accelerator center, IHEP May 10, 2007

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  1. Progress of the sub-harmonic bunching system (i.e. upgrading progress of BEPCII present bunching system) Pei Shilun for the SHBS team Accelerator center, IHEP May 10, 2007

  2. Outline • Beam dynamics simulation and mechanical layout • Design and study of the two sub-harmonic bunching cavities • Design and study of the two RF power source • Construction schedule

  3. Beam dynamics simulation and mechanical layout (1)

  4. e- Gun Buncher Standard accelerate section PB ~7nC(total) 10nC 2856MHz 2856MHz 2856MHz 350ps 10ps 1.6ns Schematic layout of the present pre-injector (Present Scheme) e- Buncher Standard accelerate section Gun SHB1 SHB2 ~9nC(total) 10nC 142.8MHz 571.2MHz 2856MHz 2856MHz 10ps 1.6ns 1.6ns 1.6ns Schematic layout of the upgraded pre-injector with 2 SHBs (Design Scheme) Schematic layout of the bunching system

  5. layout of the bunching system Remove PB、GUF6 and GUF7 Keep the arrangement of devices but move northward for 113.4cm Keep the location and arrangement of devices Install SHB1、SHB2 and 11 new coils

  6. Arrangement of devices for the new sub-harmonic bunching system Vacuum chamber Gun BPM&BCT SHB2 Bellow SHB1 BPM Vacuum valve Solenoids Solenoids Solenoids Profile Solenoids Bellows

  7. Starting with the beam parameters at the gun exit calculated with EGUN, a 150kV/10A/10nC/1.6ns(Bottom width)/0.95ns(FWHM) electron bunch is used as an input of PARMELA to simulate and optimize the beam performance of the primary electron beam at the present and the sub-harmonic bunching system exit. Beam pulse structure at the bunching system exit Present bunching system enlarged Sub-harmonic bunching system enlarged

  8. Emittance variation along the bunching system

  9. Bunching efficiency of the bunching system(charge within 10ps at the A0 exit) Present bunching system Sub-harmonic bunching system

  10. Beam envelope variation along the bunching system Present bunching system Sub-harmonic bunching system

  11. Solenoid field strength variation along the bunching system Present bunching system Sub-harmonic bunching system

  12. Physical tolerance of the new sub-harmonic bunching system • According to the simulation results with PARMELA, the physical tolerance of the new sub-harmonic bunching system can be obtained. If the physical tolerance shown in the following table cann’t be satisfied, the reduction of the bunching efficiency will be larger than 10%.

  13. Design and study of the two sub-harmonic bunching cavities (2)

  14. water channel Main parameters and structure of SHB1 Structure of SHB1 Main parameters of SHB1: • Resonant frequency: 142.8MHz • Tuning range: ~400kHz(length of tuner: 40mm、 radius of tuner: 10mm) • Q0 value: ~8175 • Shunt impedance: ~1.4MOhm • Esurface,max/Egap,max=2.53 • When Pin=10kW, Egap,max=2.70MV/m, Esurface,max=6.85MV/m, Vgap,max=118kV.

  15. SHB1 assembly SHB1 cut view Tuner cut view Long drift tube assembly Mechanical design of the SHB1

  16. Bought from HITACHI High-Technologies Corporation Monitor Coupler Short drift tube Long drift tube end-plate Mechanical design of the SHB1

  17. Main parameters and structure of SHB2 Structure of SHB2 Main parameters of SHB2: • Resonant frequency: 571.2MHz • Tuning range: ~2MHz (length of tuner: 30mm、 radius of tuner: 8mm) • Q0 value: ~13629 • Shunt impedance: ~3.7MOhm • Esurface max/Egap,max=2.44 • When Pin=4.5kW, Egap,max=3.68MV/m, Esurface,max=8.98MV/m, Vgap,max=129kV.

  18. Mechanical design of the SHB2 test cavity

  19. Cold test of the SHB2 test cavity • Frequency: 571.2MHz (Simulation: 571.2MHz) • Unloaded Q value: >10605 (Simulation: 12370) • Tuning range: 1.60MHz (Simulation: 1.40MHz) • VSWR: <1.05 (Simulation: <1.05) The measurement and the simulation consistent well!

  20. Design and study of the two RF power source (3)

  21. Schematic diagram of the RF system for BEPCII Future Linac

  22. Specification of the six reference signal generator • Input signal: 571.2MHz、-8dBm-4dBm • Output signal: f1=571.2MHz、f2=142.8MHz、f3=2856MHz、 f4=17.85MHz、 f5=71.4MHz 、 f6=499.8MHz • Output power: f1, f2, f3 >13dBm, f4, f5, f6 >10dBm • Input phase noise: >130dBc/Hz (5kHz) • Output phase noise: f1, f2, f4, f5 >110dBc/Hz (5kHz) f3, f6 >105dBc/Hz (5kHz) • Phase shift: <=±2ps/℃ • Non-harmonic restrain: >=50dBc • Harmonic restrain: >=25dBc • Output signal isolation: >=20dB • Stably operating temperature: 0~50 Degree

  23. SHB1 solid-state amplifier 1) Specification: • Frequency 142.8MHz  5.0MHz • Pulse width 10 to 70s • Repetition 1 to 100Hz • RF input power (cw) 10mW • Phase noise －110dBc/Hz (1kHz) • RF output power 20kW • Phase variation 1.5˚ (max. ) • Phase drift during pulse <1˚ • Pulse rise/fall time <1s • RF pulse flatness 2 % (max.) • RF power stability  1.5 % 2) Operation requirement: • Monitor of the output power . • Monitor of the power supply and power amplifier modules. • VSWR protection when output mismatch occurs. 3) Environment requirement: • Air conditioning, < 25℃

  24. SHB2 solid-state amplifier 1) Specification: • Frequency 571.2MHz  5.0MHz • Pulse width 10 to 70s • Repetition 1 to 100Hz • RF input power (cw) 10mW • Phase noise －110dBc/Hz (1kHz) • RF output power 10kW • Phase variation 1.5˚ (max. ) • Phase drift during pulse <1˚ • Pulse rise/fall time <1s • RF pulse flatness 2 % (max.) • RF power stability  1.5 % 2) Operation requirement: • Monitor of the output power . • Monitor of the power supply and power amplifier modules. • VSWR protection when output mismatch occurs. 3) Environment requirement: • Air conditioning, < 25℃

  25. 571.2MHz/1.5kW solid state test module for SHB2

  26. Requirements to the LLRF • Phase and amplitude stability of the SHB cavities. • Fast interlock of the SHB cavities and the power amplifiers. • Frequency tuning of the SHB cavities. • Ethernet interface for remote control. • Fast data acquisition and history recording.

  27. (4) Construction schedule • 2006.12: Detailed engineering design • 2007.1~07.10: Fabrication of all SHB components • 2007.11~07.12: Acceptance test • 2008.1~08.5: High power test in laboratory • 2008.6~08.8: Installation and commissioning • 2008.9: Operation in Linac

  28. Summary(1) • Established in the future development of BEPCII Linac, the optimized physical design of BEPCII future sub-harmonic bunching system and the optimized structure of the two SHBs are developed. • Design, fabrication and cold test of the SHB2 test cavity has been performed,the test results is consistent with the simulation. • Study of the two RF power source have been done. One test module of the solid state amplifier has been designed and tested with satisfied results.

  29. Summary(2) • Recently, the upgrading of BEPCII present bunching system to sub-harmonic bunching system has been approved by IHEP’s experts and directors. The detailed design scheme has been decided. The construction will start in this year, correspondingly, the commissioning will be started in summer of 2008 according to the construction plan. Thank the colleagues from KEKB-Linac and SLAC for their help in the past several years. The revolution is not success, everybody in the SHBS team should continue to work hard.

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