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First Mini-workshop on IHEP 1.3GHZ SRF
LLRF and Tuner
Sun YI (孙 毅)
Accelerator Center, IHEPJune 10, 2009
content• Review on BEPC RF & BEPCII S
RF
• 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 20054 cavities of 200MHz in BEPC tunnel
4 transmitters ( tetrode ) inside West RF hall2×30KW 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 panelshow different pages:1) RF system interlock2) main parameters3) 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.
CW Pulse
Feed-Back Feed-Forward
Micro-phonics ±0.50 ±3HZ
Beam Loading
QL~1.7×106 BW~764HZ
Lorentz Detune K~1.1 18MV/m ~230 153HZ
Part 3 tuner and piezo target for Q0~1010 、 QL~106→BW~1000HZ 1.3GHZ cavity freq. <±0.10 ,→ ±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
KCavity
KJacket KTuner
80 N / m 220 N / m
59 N / m
Improvement in the STF Baseline Cavities
Stiffness of Cavity Fixing Support 72 kN/mm 22 kN/mmLorentz 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 Taper13 deg. → 10 deg.
Beam Tube78 → 84
Input Port40 →
STF Baseline Cavity TTF CavityFz
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!