1. Tuner system for CEPC MI Zhenghui 2016/09/14

2. Introduction RF characteristics of cavities for CEPC
Existing tuner design
The consideration for CEPC tuners

3. RF characteristics of cavities
Parameter
Unit
Booster cavities
Main ring cavities
Cavity frequency
MHz
1300
650 QL
1E+7
1.97E+5 BW
kHz
0.065
2.1(HL),3.3(HH),5.9(Z)
Working mode
CW- Ramping CW
R/Q Ω
1036
206 G
270
268
Operating gradient
MV/m
0.81 —> 19.27
16.5
Effective acceleration length m
1.038
0.461 Vc MV
0.84 —> 20
7.61
Beam current mA
0.87
16.96*2
Bunch charge nC
3.2
45.6
Bunch number 50 ?
Tuning sensitivity
Hz/um
~340
~368
coefficient of elasticity
N/um ~3
~7.5
Working temperature K 2
Number
256
480
Cryomodule number 32 80

4. Frequency tuning requirements
Parameter
Unit
Booster tuners
Main ring tuners
Operation frequency
MHz
1300
650
cool-down uncertainties
kHz
200
Beam loading
＜ 0.7
~0.32 (0.78)
LFD
~0.4
~0.3
Tuner parameters
Coarse (slow) tuner frequency range
400
Coarse tuner frequency resolution Hz
＜20
Fine (fast) tuner frequency range ＞2
＞1.5
Fine tuner frequency resolution 2
Motor and piezo working temperature K
5~10
Motor number 1

5. Existing tuner-1 Scissors Tuner tuner for CEBAF Upgrade
Tuner for HWR Cavity FRIB
Tuner for ADS Spoke cavity
Example CEBAF (1986) to CEBAF Upgrade (2008)
Advantage
Motor and Piezo are both installed outside of Cryomodule.

6. Existing tuner-2 Blade Tuner original Blade Tuner
Revision of a lighter Blade Tuner
New design of the Blade Tuner
Working principle
Advantage
Simple structure and low cost.
25N/um

7. Existing tuner-3 Slide jack Tuner Installed middle
Installed at the end
New design of the Slide Tuner
Working principle
Advantage
High mechanical strength
wide tuning range
290N/um

8. Existing tuner-4 Saclay tuner 60N/um original Saclay Tuner
Modified Saclay Tuner
Saclay tuner for ESS
Working principle
Advantage
piezo always compressed
high reliability

9. Existing tuner-5
SNS tuner

10. Existing tuner-6
LCLSII tuner

11. Existing tuner-7

12. tuner parameters
Parameters of tuner for 1.3GHz cavity

13. tuner parameters

14. The consideration for CEPC tuner
Tuner Installation
Tuner structure is simple and easy to install；
Installed at the end of cavity (avoid interference with magnetic shielding)；
high reliability and strong maintainability
Tuner Performance

15. The consideration for CEPC tuner
Working principle
Mechanical interface is simple
Large reduction ratio
High reliability
Mechanical structure
One motor + Two Piezoes
Motor and Piezoes at the same side

16. Diagrammatic sketch
1.3GHz cavity and 650MHz cavity use the same type tuner.
Tuner two arms are connected.
2K low temperature test must be carried out!!!

17. Operational strategy based on previous failures(SNS)
Tuners are tested before and after every 2K to 4K or 4K to 2K transition
Approximately 20 tuner repairs have been performed at SNS
Access ports allow in-situ repair of tuners in tunnel
Vibration monitoring with RF
Alignment
Bigger vibration and/or more frequent tuner motion lower gradient detune/turn–off.

18. Tuner test stand For CEPC Tuner test:
① Use the cryomodule in the NO.1 building
② Use the vertical test Dewar
Fermilab tuner test
SNS tuner life test
Piezo tuner test stand

19. Thanks