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Blade and Piezo Tuners Overview

Blade and Piezo Tuners Overview Justin Keung University of Pennsylvania January 16, 2007 1m Lorentz Detuning As the cavity accelerating gradient increases, the pressure due to radiation becomes significant Recall: Cross section of one-cell cavity

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Blade and Piezo Tuners Overview

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  1. Blade and Piezo Tuners Overview Justin Keung University of Pennsylvania January 16, 2007 1m

  2. Lorentz Detuning Justin Keung, University of Pennsylvania • As the cavity accelerating gradient increases, the pressure due to radiation becomes significant • Recall: • Cross section of one-cell cavity • Red line represents the cavity design contour • Blue line shows the deformed shape • Cavity deformation causes change in natural resonant frequency • Piezo Tuner to compensate Estimation of Lorentz Detuning and Related Tuning Characteristics of ICHIRO Cavity, T. Higo et al., KEK, 2006

  3. Mechanical Resonance Justin Keung, University of Pennsylvania • Entire cryomodule can vibrate at mechanical modes • (your hand can feel the cryomodule vibrate!) • Changes the shape of the cavities periodically • Resting cavity resonates at ~42Hz, beam arrival excites a ~180Hz resonance • The 180Hz resonance decay constant is about 0.7 second • ILC will have only 0.2 seconds between beam pulses • Piezo Tuner to compensate ILC FAST TUNER R&D PROGRAM at FNAL, Status Report CC2 Piezo Test Preliminary Results, Ruben Carcagno et al., 2006

  4. What are Tuners? Justin Keung, University of Pennsylvania • Piezoelectric Crystals and Blade Tuner • Changing the natural frequency of the cavity (tuning) by changing its size • 22.5MHz +-15% per 1mm of the cavity flange to flange distance • Piezos tuners – “fast” • Actively control cavity tuning (10-6 s time scale) • The same piezo crystals concurrently measures the noise and compensates for it • Blade tuners – “slow” • One time tuning, after cavity cools to 2K

  5. Piezos and Blade Tuner Justin Keung, University of Pennsylvania 300cm 1cm Top left: complete Piezo and Blade Tuner Top right: blade tuner unmounted Bottom left: piezo tuner unmounted Bottom right: Piezo tuner mounted

  6. Blade Tuner In Action Justin Keung, University of Pennsylvania Time lapsed video of the blade tuner changing the natural frequency of the cavity (orange line shifting). The blue line represent the frequency away from 1.3GHz, in units of 135kHz/mV. Blade tuner has tuning range of ~30.8MHz+-2%. One step of the motor moves the screw forward/backward by 1.6nm+-2%, and changes the resonant frequency by 2.3Hz+-2%

  7. Piezo Tuner: Actuator Justin Keung, University of Pennsylvania Representation of the before (left) and after (right) the piezo tuner changing the natural frequency of the cavity (orange line shifting). Actual measurement done with locating the frequency of the peak before and after the application of piezo voltage. 150V applied on the 9 stack (of the 9+1 stack) moves the frequency at the peak by 18kHz+-12.5%.

  8. Piezo Tuners: Sensor Justin Keung, University of Pennsylvania Signal is a result of hammering the table. Blue: signal from monitor piezo, 2mm. Green: same signal from drive piezo, 6mm. (smaller amplitude, but signal received) This demonstrates the plausibility of using the same piezo to both sense/actuate.

  9. Piezo: Sensor & Actuator Justin Keung, University of Pennsylvania This board, using the actuator piezo, is able to extract the same signal as the sensor piezo. This board also controls the actuator piezo.

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