First Mini-workshop on IHEP 1.3GHZ SRF LLRF and Tuner Sun YI （孙 毅） Accelerator Center, IHEP June 10, 2009

content Review on BEPC RF & BEPCII SRF Block diagram of 1.3GHZ LLRF Tuner and piezo of 9-cell cavity Problems Summary

Beijing Electron Positron Collider (BEPC) Institute of High Energy Physics, CAS

The old BEPC was one Ring machine before the upgrade at cavities of 200MHz in BEPC tunnel 4 transmitters ( tetrode ) inside West RF hall 2×30KW to feed one cavity ( 200MHz ) LLRF station for 4 cavities

2 LLRF stations are located respectively at the East/west RF hall beside each Klystron & PS, the cryogenic hall is above the test room

PLC touch panel for each SRF station

In a station: Superconducting cavity,250KW klystron and LLRF control system

PLC touch panel show different pages: 1) RF system interlock 2) main parameters 3) plot 4) cryogenic & cavity Q0

Part 2 block diagram of 1.3GHZ LLRF

F-1 signal generation

Prof. Wang Guangwei is in charge of the R&D of the FB loops of LLRF. Liu Rong ( PH.D student ) will visit KEK and work at STF for the digital LLRF feedback loops on Sep., 2009 LLRF workshop will be hold on Oct.,2009 at KEK, A chance of discussion and working for the FB loops at STF.

CWPulse Feed-BackFeed-Forward Micro-phonics±0.5 0 ±3HZ Beam Loading Q L ~1.7×10 6 BW~764HZ Lorentz Detune K~1.1 18MV/m~ HZ Part 3 tuner and piezo target for Q 0 ~10 10 、 Q L ~10 6 →BW~1000HZ 1.3GHZ cavity freq. <±0.1 0 ， →±1HZ →dynamic range±~3nm STF target : →±50HZ ( with beam?)

4 kinds of tuner Coaxial Ball Screw 500N/mm (Saito) Blade 25N/um ( INFN for TTF )Slide Jack 290N/mm (STF) Cam+lever 60N/um (Saclay-2)

First try to test a slide jack tuner IHEP case: one cavity in one cryostat Spring compensation for BEPCII cavity STF cavity only rely on elastic force ? (without compensation spring) How to “pre-tuning” under 2K?

BEPCII 超导腔调谐补偿弹簧示意图

Conception design of tuner and cryostat is on the way

IHEP 1.3GHZ SCC tuner

STF freq. vs tuner position ≈300KHZ/mm

IHEP need more Simulation and calculation cavity freq. ~ tuner force ~ Ti jacket Stiffness IHEP should reduce the mistakes and risks before the fabrication of the tuner.

Stiffness of the Tuner System K Cavity K Jacket K Tuner 80 N /  m220 N /  m 59 N /  m

Improvement in the STF Baseline Cavities Stiffness of Cavity Fixing Support 72 kN/mm 22 kN/mm Lorentz Detuning -520 Hz -870 Hz (31.5 MV/m) TTF Cavity Inside M – Shield. Thick Titanium Baseplate, Thick Nb Beam Tube & Thick Nb End-cell STF Baseline Cavity Cell Taper 13 deg. → 10 deg. Beam Tube  78 →  84 Input Port  40 →  STF Baseline CavityTTF Cavity Ｆｚ Ｆｒ

Part 4 problems: Location of Tuner ( in the middle or in one side of cryostat ? )

直线导轨 Linear guider 丝杠螺母机构 齿轮传 动机构 Piezo 孔 参考面 基准面 Upgrade to STF tuner is possible?

Other questions STF tuner had been test at RT, cold test on the tuner is needed? The motor screw is too long, why STF did not set the motor inside the tank? How to measure the tuner position? The materials of roller wedge and ball? Details of the taper gear, and motor gear box Materials of tuner flange and 4 supporting rod?

summary IHEP have collected experience on the KEKB superconducting cavity, and have a happy history of the co-operation with KEK the design on 1.3GHZ tuner and LLRF has been begun since the end of 2008, there is a hard way to reach the test with cavity. IHEP still keep a lot of questions and hope the help from STF experts THANKS!