1. Mechanical setups Lorentz Force Detuning System Setup
Tuners
Mechanical setups
Lorentz Force Detuning System Setup
Lutz Lilje DESY -MPY-

2. Frequency Tuner Tuner consists of 2 parts Slow tuner Fast tuner
Allow for different thermal shrinkage
Correct slow drifts e.g. He pressure
Specification:
Range: 820 kHz
Resolution: 1 Hz /step
2 basic types have been tested
Lateral (Saclay)
Coaxial (INFN, DESY)
Fast tuner
Compensate Lorentz-forces
df <= 1 kHz in 1 ms
Piezoelectric
Frequency Tuner
Lutz Lilje DESY -MPY-

3. Lateral Tuner (Saclay)
Design by M. Maurier and P. Leconte based of the MACSE tuner design
DLscrew
DLarms
DLcavity
Used in TTF
Double lever system: ratio ~ 1/17
Stepping motor with Harmonic Drive gear box
Screw – nut system
Needs space between cavities
Interferes with HOM couplers
More compact design seems feasible
Lutz Lilje DESY -MPY-

4. New Saclay Tuner Design by P. Bosland More compact design possible
Cavity should be pre-tuned so that the tuner is not pushing
Piezo integrated
Available by the end of the year for first tests
Lutz Lilje DESY -MPY-

5. New Saclay Tuner 2
Lutz Lilje DESY -MPY-

6. New Saclay Tuner 3
Lutz Lilje DESY -MPY-

7. New Saclay Tuner 4
Lutz Lilje DESY -MPY-

8. Coaxial Tuner (INFN, DESY)
On the He vessel
Tested on the superstructure in TTF (4 units)
Magnetic shielding more difficult
2nd design exists
Test in CHECHIA done
Lutz Lilje DESY -MPY-

9. Lorentz Force Detuning System Setup
Setup description
Single pulse compensation
Resonant excitation
Problems
Lutz Lilje DESY -MPY-

10. Lorentz Force Detuning System Setup
Function Generator
ADC
PZD Amplifier
Piezo actuator
Piezo sensor
PZM Amplifier
DOOCS server
Amplifier
Lock-in or
Logarithmic
Chechia
Matlab
Fgen.m
chread.m
LP filter
Lutz Lilje DESY -MPY-

11. Piezoelectric tuner I M. Liepe, S. Simrock, W.D.-Moeller
Tuning mechanism
Piezo
Piezo-Actuator:
l=39mm
Umax=150V
 l=3m at 2K
fmax,static=500Hz
He-Tank
& Cavity
Lutz Lilje DESY -MPY-

12. Piezo Tuner setup II Sensor-Actuator configuration
To compensate for Lorentz force detuning during the 1 ms RF pulse
Feed-Forward
To counteract mechanical noise, “microphonics”
Feed-Back
Lutz Lilje DESY -MPY-

13. Drawing of current setup (H.-B. Peters)
Lutz Lilje DESY -MPY-

14. RF signals at 35 MV/m Blue: With piezo Red: Without piezo
Lutz Lilje DESY -MPY-

15. RF pulse (500us fill, 800us flat-top)
Piezo excitation of the cavity for frequency compensation (operation for 700 hours)
RF pulse (500us fill, 800us flat-top)
Lutz Lilje DESY -MPY-

16. Single pulse compensation
Pulse Parameters:
frequency = 219 Hz
time delay = 0.84 ms
amplitude = 95V
Lutz Lilje DESY -MPY-

17. Single pulse compensation
MICROPHONICS
Lutz Lilje DESY -MPY-

18. Damping of the ringing between pulses (5Hz operation)
RF pulse
RF pulse
RF pulse
Lutz Lilje DESY -MPY-

19. Frequency stabilization during RF pulse using a piezoelectric tuner
Blue: With piezo
Red: Without piezo
Frequency detuning of 500 Hz compensated voltage pulse (~100 V) on the piezo. No resonant compensation
Frequency stabilization during RF pulse using a piezoelectric tuner
Lutz Lilje DESY -MPY-

20. Option: Resonant excitation of a mechanical cavity resonance
if one excites a mechanical resonance of a cavity with the piezo, one can use the cavity as an mechanical amplifier, so that a small stroke of the active element can compensate large detuning
we have shown that with the excitation of three periods of the mechanical resonance frequency, about 1000 Hz could be compensated
Lutz Lilje DESY -MPY-

21. Resonant excitation (stable for 200 hours)
Pulse Parameters:
frequency = 219 Hz
time shift = -9.5 ms
amplitude = 24V
offset = 24V
Lutz Lilje DESY -MPY-

22. Resonant excitation
Lutz Lilje DESY -MPY-

23. Frequency stabilization at 35 MV/m
Blue: With piezo
Red: Without piezo
Frequency detuning of ~1000 Hz compensated with resonant excitation of a mechanical cavity resonance at 230 Hz.
NOTE: This is rather an demonstration of the capability of active tuning. Application in a real machine is probably difficult/ impossible. Needs investigation.
Lutz Lilje DESY -MPY-

24. Module Measurements
Lutz Lilje DESY -MPY-

25. Single Piezo - Single Pulse Compensation
inside the module
f=200Hz, only 100Hz compensation
Lutz Lilje DESY -MPY-

26. Single Piezo - Resonant
Lutz Lilje DESY -MPY-

27. Problems with the active tuner
Fundamental problem:
Preload at operating temperature not defined
Large tuning needed for both cavities tested in CHECHIA (AC72, AC73)
´natural´ frequency after tank welding is 780 kHz above 1,3 GHz
Normally this is more like kHz
This results in a very large force tearing on the piezo fixture
Fixtures open up and piezos become loose
Lutz Lilje DESY -MPY-

28. Force Measurement at the Piezo Position
Design by Karsten Gadow (H1)
Available before end of the year
Detailed measurement of the force in the cold environment
Calibration will be first done to liquid nitrogen temperatures
Then design a fixture with sufficient stiffness
Lutz Lilje DESY -MPY-

29. Problems with active tuning
Single Piezo fixture
So far only Hz compensated (no resonant excitation of the cavity)
Achieved compensation at 1,3 GHz
Alternative: Resonant mechanical excitation of the cavity
Double Piezo fixture
Has only been operated at 1,3 GHz + 600kHz
Needs a stiffer design
Alternative: Put 2 single Piezo fixtures at different posts of the tuner
Bipolar operation of Piezos helps in any case
Check in CHECHIA and INFN
Lutz Lilje DESY -MPY-

30. Fixture twists during operation
Fixture Twist Problem 
Fixture twists during operation
Lutz Lilje DESY -MPY-

31. Problems with active tuning
Automation is needed for operation of the piezos in the machine
Determination of optimum pulse shape
Interconnection to LLRF system
Lutz Lilje DESY -MPY-

32. Available piezos (1/2) EPCOS NOLIAC Piezo Mechanik
Physical Instruments
Lutz Lilje DESY -MPY-

33. Available piezos (2/2) Mechanical Electrical Lutz Lilje DESY -MPY-

34. Conclusion Proof-of-principle Engeneering is needed
Single-piezo
Non-resonant:100Hz in the module
Resonant: 200 Hz in the module
(We can use this in module 6!)
Double-piezo
Non-resonant: 400 Hz (not at 1.3GHz exact)
Resonant: 1kHz
Test of bipolar operation
Engeneering is needed
Choice of Piezo (-> together with INFN, IPN Orsay))
Stiffer Piezo fixture/frame for 2 Piezos
Force measurement is underway (finished end 2004?)
LLRF integration
New Saclay tuner tests needed
Available end 2004 / beginning 2005
Change of cavity pre-tuning desirable
Conclusion
Lutz Lilje DESY -MPY-