Institut de recherche sur les lois fondamentales de l'Univers

Linear colliders and free-electron lasers projects based
on the superconducting RF technology require high
gradient pulsed operation of superconducting elliptical
multicells. The cavities are subject to Lorentz force
detuning (LFD) which reflects on an increased RF power
consumption when trying to stabilize the accelerating
field during the beam passage. This pulsed detuning can
be mechanically compensated using a fast piezoelectric
tuner. A new tuner with integrated piezoelectric actuators
has been developed in the framework of CARE/SRF
European program. The tuning system has been tested on
a fully equipped 9-cell TTF cavity in the CRYHOLAB
horizontal cryostat using the pulsed 1.3 GHz 1.5 MW RF
source. In virtue of the high pulse to pulse repeatability of
the detuning, the compensation of Lorentz detuning was
achieved successfully using a simple feed forward
scheme.