1. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Performance of magnetostrictive element at LHe environment M.Grecki, P. Sekalski Department of Microelectronics and Computer Science Technical University of Lodz, Poland C.Albrecht Deutsches Elektronen-Synchrotron Hamburg, Germany

2. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Outline Motivation of experiment, Magnetostrictive tuner specification, Experiment description, Plans for future,

3. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Motivation for experiment The change of the resonant frequency of the cavity, The master oscillator frequency is constant. The cavities are pulsed at high field. The electromagnetic field interacts with cavity walls The cavity changes its dimensions De-tuned cavity, T T De- (Lorentz force) De-tuned cavity Magnetostrictive elements: might have a higher lifetime, are immune to shortcuts, generate less heat, Magnetostriction of different materials in function of temperature (courtesy of ENERGEN).

4. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Magnetostrictive tuner specifications 22 mm50 mm 61.8 mm

5. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Magnetostrictive tuner prototype Plunger & Belleville springs Active magnetostrictive element with ferrite, s.c. coil and thermal connectors Niobium Cover Magnetostrictive rod (made of Kelvin ALL ® ) Build by ENERGEN Inc. Ferrite necessary to close magnetic circuit Superconducting coil (Nb 3 Sn) Thermal connectors

6. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Magnetostrictive tuner experiment Experiment goals Run tuner at low temperature, Transfer function from magnetostrictive element to piezoelectric one Transfer function from piezoelectric element to magnetostrictive one Characterize magnetostrictive tuner vs. NOLIAC piezo stack (similar experiment with two piezostacks was done) - stroke vs applied current - maximal frequency Heat dissipation (temperature rise)

7. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Power Transconductance Amplifier Technical Specifications: Maximum output current amplitude – 8 A Maximum pulse duration – 2.3 ms Maximum repetition frequency – 20 Hz Amplification – 3.33 A/V Schematic of amplifier (designed by G. Jablonski, DMCS-TUL) PTA based on PA93 APEX Power Operational Amplifier PWM amplifier is under investigation

8. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Magnetostrictive tuner experiment The data obtained by Energen „is” done for preload of 400N. (no measurement for preload was performed at LHe temperature) Measured dataCalibration data from INFN ~2μm of displacement for 8A

9. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Magnetostrictive tuner - future test Two new magnetostrictive rods from EXTREMA are ordered. They are made of GalFeNOL. We would like to perform a characterization of all 3 rods (or more if possible) similar to the piezo one, including: –Displacement measurement versus magnetic field applied to device for different preload settings (i.e. 0N, 1kN, 2kN, 3kN), –Max. stroke, –Dynamics of motion, –Heat generation – coil is made of Nb 3 Sn, –Magnetic field distribution (if possible)

10. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Flange for high current wires (up to 16 Amps) Flange for temperature and magnetic field sensors wires Interface need to be designed Displacement sensor Magnetic field sensors Magnetostrictive rod inside superconducting coil Membrane Screw for preload force adjustment Temperature sensors (its positions are under investigation ) Magnetostrictive tuner - future test

11. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Conclusions The maximal displacement of magnetostrictive tuner was less than 2um. The data might be not exact, because the preload force and boundary condition were not well controlled (It might happen that the preload force was higher than 1kN, because stiffness of fixture was unknown at low temperature). Small delay between input and output signal might be observed (around 70us). In principle it might be explained by the magnetostrictive element hysteresis (as it is observed in RT temperature). Finally, performed experiment does not give the quantify results, but the main goal of test was reached: the tuner was run successfully at LHe temperature. On the other hand, the detailed magnetostrictive rod characterization is strongly required. Using the obtained experiences, the proper experiment will be prepared and performed soon.

12. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 References [1] “TESLA Technical Design Report”, DESY 2001-011, 2001 [2] T. Schilcher, “Vector Sum Control of Pulsed Accelerating Field in Lorentz Force Detuned Superconducting Cavities“, PhD thesis [4] S.N. Simrock, “Lorentz Force Compensation of Pulsed SRF Cavities”, Proceedings of LINAC 2002, Gyeongju, Korea [5] M. Liepe, W.D.-Moeller, S.N. Simrock, “Dynamic Lorentz Force Compensation with a Fast Piezoelectric Tuner”, Proceedings of the 2001 Particle Accelerator Conference, Chicago [6] L. Lilje, S. Simrock, D. Kostin, M. Fouaidy, “Characteristics of a fast Piezo-Tuning Mechanism for Superconducting Cavities”, Proceedings of EPAC 2002, Paris, France. [7] P. Sekalski, S. Simrock, L. Lilje, C. Albrecht, “Lorentz Force Detuning Compensation System for Accelerating Field Gradients up to 35 MV/m for Superconducting XFEL and TESLA Nine-Cell Cavities”, MIXDES 2004, Poland [8] Magnetostrictive tuner datasheet, ENERGEN, INC

13. Performance of magnetostrictive element at LHe environment 12th International Conference MIXDES 2005 Thank you for your attention