Abstracts Brochure - CERN

MOPCH — Poster Session 26-Jun-06 16:00 - 18:00
techniques solely would be too costly. A new active tuner with integrated piezo actuators has been developped in
the framework of the european CARE/SRF program solve this issue. The design is based on the lever-arm concept
of the Saclay tuner already installed on running TTF cavities. We have carried out integrated tests of the 9-cell cavity
equipped with the piezo tuner and power coupler in the CryHoLab horizontal test cryostat. Characterisation of
the electromechanical system consisting of the cavity and piezo-tuner assembly and full power pulsed tests will be
presented.
Alternative Baking Process for Mass Production of Nb Superconducting RF Cavities
Baking is a necessary stage to reach high gradients
with niobium superconducting cavi- B. Visentin, J.-P. Charrier, Y. Gasser, S. Regnaud (CEA)
ties. In the standard process, so called "insitu
UHV baking", Nb cavity is baked at 110 o C, during 2 days. During this treatment the inner part of the cavity is
pumped out under Ultra High Vacuum conditions. In order to save time, "fast UHV baking" at 145 o C during 3 hours,
under UHV pumping, has been successfully demonstrated* with similar improvements for cavity performances compare
to the standard treatment. With the same simplification concern, we report here about an alternative method
to avoid restrictive UHV requirements. Experiments have been carried out to perform "fast baking" in oxygen-free
atmosphere, because bad performances have been observed with "fast baking" in air. These degradations are closely
connected with a strong oxygen penetration in bulk analysed by Secondary Ion Mass Spectroscopyon on Nb samples
.
*Proceedings of SRF Workshop – Ithaca (July 2005) – TuP05.
Commissioning of the SOLEIL RF Systems
The 352 MHz RF accelerating systems for the
SOLEIL Booster (BO) and Storage Ring (SR)
are being commissioned. In the BO a 5-cell
copper cavity of the CERN-LEP type is powered
with a 35kW solid state amplifier. In the
SR the required RF accelerating voltage (up
P. Marchand, H.D. Dias, M.D. Diop, M.E. El Ajjouri, J.L. Labelle,
R.L. Lopes, M. Louvet, C.M. Monnot, J. Polian, F. Ribeiro,
T. Ruan, R.S. Sreedharan, K. Tavakoli, C. Thomas-Madec (SOLEIL)
P. Bosland, P. Bredy (CEA)
to 4.4MV) will be provided by two cryomodules, each containing a pair of superconducting cavities, specifically
designed for SOLEIL. The parasitic impedances of the high order modes are strongly attenuated by means of four
coaxial couplers, located on the tube connecting the two cavities. The first cryomodule is already installed in the SR
tunnel, while the second one is being constructed by ACCEL (Germany). These cryomodules are supplied in liquid
helium from a single 350W liquefier and each cavity is powered with a 190kW solid state amplifier. The RF system
commissioning and first operation results are reported.
Electromechanical Characterization of Piezoelectric Actuators Subjected to a Variable Preloading
Force at Cryogenic Temperatures
Piezoelectric actuators are actually used in
Fast Active Cold Tuning Systems (FACTS) M. Fouaidy, N. Hammoudi, L.S. Lionel, M.S. Saki (IPN)
for SRF cavities. The characteristics, performances
and lifetime of these actuators depend on the preloading force applied by the cavity and the FACTS to the
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