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XFEL Tuner

XFEL Tuner. Lorentz Force Detuning System Setup New Saclay design. General Remarks. Available today Old Saclay Tuner Simple Single Piezo fixture 150-200 Hz compensation Feedforward works well Piezo stacks Desirable Two piezo fixture Sensor-Actuator configuration

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XFEL Tuner

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  1. XFEL Tuner Lorentz Force Detuning System Setup New Saclay design Lutz Lilje DESY -MPY-

  2. General Remarks • Available today • Old Saclay Tuner • Simple Single Piezo fixture • 150-200 Hz compensation • Feedforward works well • Piezo stacks • Desirable • Two piezo fixture • Sensor-Actuator configuration • Future Option: Feedback on sensor piezo? • Bipolar operation to gain more stroke from Piezo • At cold stroke of piezo is smaller by up to a factor of 10… • … but the material is more forgiving • New Saclay Tuner Lutz Lilje DESY -MPY-

  3. General remarks II • Need engineering • Detailed study on forces at the piezo position • Cold force sensor built by H1 • Test in CHECHIA • Design of fixture/frame for 2 piezos • Selection of best Piezo supplier • Material • INFN works on that • Control system • Driver Amplifier modification for bipolar operation • Need automated procedures to setup Piezo • Collaboration with INFN • Detuning measurement • Preferably in one pulse • Warsaw colleagues are working on this Lutz Lilje DESY -MPY-

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

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

  6. Piezo Driver Amplifier (PZD) • Specification: • Gain of the unloaded amplifier: –38 V/V (0.15), • Output voltage range from -160.9 V to +70 V,(voltage limiter) • Voltage offset: 0,11V • Output voltage rise and fall time: 200s (-160V  +60V) • Maximal pulse current 2A (1ms) • Capacitive load  1,5F Lutz Lilje DESY -MPY-

  7. Piezo Measurement Amplifier (PZM) • Specification: • Gain : 0.5 V/V, (adjustable), • Bandwidth: 100kHz, • Input impedance: 1k, • Output voltage range: ±5V, • Analog output 50 . Lutz Lilje DESY -MPY-

  8. Piezoelectric tuner IM. 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-

  9. 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-

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

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

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

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

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

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

  16. 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-

  17. 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-

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

  19. Resonant excitation Lutz Lilje DESY -MPY-

  20. 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-

  21. Module Measurements Lutz Lilje DESY -MPY-

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

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

  24. 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 200-300 kHz • This results in a very large force tearing on the piezo fixture • Fixtures open up and piezos become loose Lutz Lilje DESY -MPY-

  25. Design by Karsten Gadow (H1) Available within 2-3 weeks 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 Force Measurement at the Piezo Position Lutz Lilje DESY -MPY-

  26. Problems with active tuning • Single Piezo fixture • So far only 100-200 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-

  27. Fixture Twist Problem  Fixture twistsduring operation Lutz Lilje DESY -MPY-

  28. 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-

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

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

  31. 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-

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

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

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

  35. Conclusion • Proof-of-principle • 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 Lutz Lilje DESY -MPY-

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