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SRF2003 Show Abstract


Title CHARACTERIZATION OF PIEZOELECTRIC ACTUATORS USED FOR SRF CAVITIES ACTIVE TUNING AT LOW TEMPERATURE
Type Poster coupler / tuner / controls
Abstract Superconducting RF (SRF) cavities are very sensitive to small mechanical perturbations due to their narrow bandwidth. High electromagnetic fields induce   mechanical deformation in the micron range  leading to a  frequency detuning of the same order of magnitude of the bandwidth of these accelerating structures. In order to reduce this effect, which results other ways in a substantial additional RF power so as to control the electromagnetic fields, the SRF cavities are stiffened. However, the detuning factor reached with stiffened SRF cavities is still much higher than needed. An alternative strategy or dynamic compensation of Lorenz Force detuning based on commercial piezoelectric actuators was proposed recently and the principle was demonstrated on TESLA cavities. A piezo-tuning system is actually developed at IPN Orsay for high intensity proton linacs SRF cavities. A dedicated facility was designed and successfully used for the characterization of piezoelectric capacitive actuators at low temperature (i.e 1.8 K-300K). This device is described and the first experimental results (i.e piezoelectric actuator calibration or displacement DX vs. applied voltage V, capacitance C vs. T dielectric properties vs. T and frequency) are analyzed and discussed. The experimental data show that the full range displacement DX of the actuator decreases strongly with T. For the actuators studied, the variations of dielectric losses with T for a sine displacement of given amplitude (1 micrometer) show a maximum around 10 K-20 K leading to a thermal load lower than 1 mW at 1.8 K for a sinusoidal displacement of 1 micrometer at a frequency of 100 Hz

List of authors...

Principle author first.

Last (Family) Name First Name (Initials only) Affiliation or Organization (abbreviations if possible)
FOUAIDY M IPN Orsay
HAMMOUDI N  



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