COLD TUNING SYSTEM DEDICATED TO 700 MHZ SUPERCONDUCTING ELLIPTICAL CAVITY FOR PROTONS LINAC

A first prototype of a slow cold tuning system have been developed for SRF 700 MHz (β= 0.65) cavity dedicated to high intensity protons linac. This tuner, which is based on the CEA “Soleil” type tuning system, has been tested at cryogenic temperatures in the “CRYHOLAB” test facility. The first experimental results show a good mechanical behaviour and should be completed with long term tests. In parallel, a piezo-tuner is under study: it will be equipped with piezoelectric actuators for fast tuning purpose (Dynamic compensation of Lorentz forces effect, microphonics…). Full characterizations of piezoelectric actuators from various firms were performed at low temperature in order to measure the electromechanical parameters (stroke, dielectric, thermal and mechanical properties) needed for the mechanical design and optimization of the fast tuner.