| Paper | Title | Page |
|---|
| TUP48 | Dry-ICE Cleaning: The Most Effective Cleaning Process for SRF Cavities? | 239 |
| | - D. Reschke, A. Brinkmann, K. Floettmann, D. Klinke, J. Ziegler
DESY - D. Werner, R. Grimme, Ch. Zorn
Fraunhofer IPA
| |
| | The dry-ice sublimation-impulse cleaning (DIC)
technique using a two component ring jet has been proven
as a highly efficient cleaning process for niobium and
copper surfaces. The liquid carbon dioxide flows through
a ring-type nozzle assembled in a purpose-built cleaning
head, expands to form a dry-ice / gas mixture and is
accelerated by the surrounding nitrogen. A set-up for the
HORIZONTAL cleaning of single-cell niobium cavities
has been successfully commissioned during the last years.
A preliminary parameter set for effective final cleaning is
established. Several cavities have been cleaned and tested
without any detectable field emission up to 36 MV/m. As
application of the DIC technique might result in
additional cleaning potential for accelerator structures, an
extension of the set-up and testing of nine-cell cavities is
planned until mid of 2008. Furthermore, DIC was applied
to the copper injector "gun" cavity for TTF/FLASH [1]
recently. In order to reduce the dark current of the gun
cavity, a vertical cleaning setup was developed and tested. | |
| 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. | |
| TUP74 | Progress of the Test Cavity Program for the European XFEL | 327 |
| | - A. Brinkmann, J. Iversen, D. Reschke, W. Singer, X. Singer, K. Twarowski, J. Ziegler
DESY Hamburg
| |
| | Two main goals of the test cavity program for the
European XFEL are the qualification of alternative
niobium vendors and the investigation of the capabilities
of large grain niobium for large-scale nine-cell cavity
production. About 25 1.3 GHz single-cell cavities of
TESLA shape have been completed at Accel Instruments
and DESY. Alternative vendors for high purity fine-grain
niobium are ITEP Giredmet, Cabot, Ningxia and Plansee.
The in-house fabricated cavities have been tested after
800C firing and final electropolishing (EP) treatment. All
cavities exceed gradients of 35 MV/m at high Q-values.
For the large grain cavities of high RRR Heraeus niobium
gradients up to 41 MV/m have been achieved. The
performance after final chemical etching (BCP) is
compared to EP for several cavities. | |