1. Tuner system Zhenghui MI 2017/01/17

2. Introduction
Tuner design
Vertical test
CDR (Tuner)
Others

3. Tuner design
General
•  SRF cavities require frequency tuning systems regardless of their application. The uncertainties in cool-down shifts are typically too large to be acceptable. Furthermore, in case of malfunctions in a cavity, one would like to be able to de-tune it from resonance. These are one-time adjustments, without speed requirements, with large range (large forces, large travel).
Specific
•  In pulsed regime, the behavior of an SRF cavity is dominated by Lorentz force detuning. Maintaining the cavity locked onto the design frequency may require a fast pulse-to-pulse compensation from the tuner, typically with a small range.
•  In CW regime instead the behavior is dominated by fluctuations in the Helium bath pressure which require a slow compensation.

4. Tuner design Small Bandwidths
•  For cavities with bandwidths increasingly small, you will need to adjust the frequency with more and more fine resolution. (e.g. Hertz = nanometers!). Requires microscopic and repeatable motions which are hard to achieve with motors and complex mechanisms
•  Resolution requirements are tightly correlated with hysteresis requirements. You can’t achieve high resolution control if you have hysteresis issues (i.e. a backlash/delay between actuation and frequency changes).
•  Small bandwidths require silent systems during operation. You may have problems actuating motors during beam-time due to vibrations.

5. Active and Passive control
•  Active control of frequency refers to a feedback system and actuation devices to compensate the causes of shifts in the cavity.
•  Passive control involves all those methods aimed at making the cavity less susceptible to perturbations or at reducing the perturbations (e.g. He pressure regulation).
•  For cavities with small bandwidths, passive control is imperative.

6. Tuner survey 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.

7. 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

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. 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

14. 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

15. Tuner design Main parameters of tuner 650MHz cavity + tuner
Unit
Booster tuners
Main ring tuners
Operation frequency
MHz
1300
650
Cooling-down uncertainties
kHz 50
Beam loading
＜0.7
~ 0.32/0.78
LFD
~ 0.4
~ 0.3
Detuning protection
200
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
Piezo number
650MHz cavity + tuner
1.3 GHz cavity tuner

16. VT system Magnetic measurement instrument
Prepare for superconducting cavity expulse flux research

17. 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

18. CDR

19. Others Tuner Bellow Coupler
650 MHz Cavity string （Cavity + Coupler + tuner）

20. 1.3 GHz 9 cell cavity
1.3 GHz 2 cell cavity

21. 谢 谢！