| Paper | Title | Page |
|---|
| TUP69 | Optimization of Baking Parameters for Electropolished Niobium Superconducting Cavities | 304 |
| | - B. Visentin, Y. Gasser, M. Bruchon, F. Eozenou, J. P. Charrier
CEA-Saclay - D. Reschke, A. Brinkmann
DESY Hamburg
| |
| | High gradients, on bulk niobium cavities, can only be
reached after an imperative baking at low temperature
to suppress the high field Q-drop.
We demonstrate in this paper that the commonly used
standard process (under ultra high vacuum at 120 degree C for
48 hours) could be now simplified in terms of duration
(3 hours at 145 degree C) and requirement (argon atmosphere
instead of vacuum). Some efforts to more reduce
duration, down to only one hour, have been undertaken
to validate hypothesis and understand baking
phenomenon. The next improvement step with the
open-ended treatment of cavities in oxygen free
atmosphere is underway and it does not seem hard to
achieve. This new "fast baking" procedure will be very
useful in the XFEL and ILC projects where Nb cavities
mass production is required. | |
| TUP80 | Single Cell Electro-Polishing at CEA Saclay: First Results | 343 |
| | - F. Eozenou, M. Bruchon, Y. Gasser, Y. Boudigou, B. Visentin, J. P. Charrier, S. Berry, C. Antoine
CEA-Saclay - D. Reschke
DESY Hamburg
| |
| | The goal of the Work Package 5.1 of the CARE SRF
program is to study electro-polishing (EP) of niobium and
thus isolate an ideal set of parameters for 1.3 GHz single
cell cavity treatment that should be applied to industry.
The more challenging aspect concerns acid composition's
optimisation, made of a mixture of hydrofluoric (HF) and
sulfuric (H2SO4) acids with possible additional water.
Preliminary experiments have been carried out on
samples to guide the program on single-cell cavities. In
that way, a set-up for horizontal EP has been installed in
our laboratory.
This set-up has been successfully qualified with the
standard recipe used at DESY since the first EP on
TESLA-shaped cavity has reached an excellent gradient
above 42 MV/m. The search for new parameters makes
then sense. Different configurations have been
investigated: higher temperature, lower voltage and new
acids' concentrations. Dummy cavities have been electropolished
with a new mixture:
1vol HF(40w%) - 2vol H2SO4(95w%) - 7vol H2O,
(1-2-7) with high water content.
Different cavities have also been electro-polished and
results including surface aspect, RF measurements and
impurities forming will be related. | |