| Paper | Title | Page |
|---|
| TUP44 | Development and RF Test Results of a New HF and H2SO4 Free Electro Polishing Method for Superconducting Niobium Cavities | 227 |
| | - M. Pekeler, S. Bauer, H. Vogel
ACCEL - D. Reschke, J. Ziegler
DESY
| |
| | A new Electro Polishing method for superconducting
cavities using an acid mixture without hydrofluoric and
sulphuric acid was developed at ACCEL Instruments
GmbH based on an exclusive license from Poligrat GmbH
in Munich, Germany (patent pending). Two 1.3 GHz
single cell cavities were built and are used for
qualification of the new Electro Polishing method. After
the Electro Polishing at ACCEL, the cavities are
transported to DESY for RF testing. At DESY no further
surface removal by any means is done, but a high pressure
water rinsing is carried out. Very promising test results
were achieved right away. During the first RF test of the
first treated cavity, Q values above 2x10^10 and accelerating
gradients above 20 MV/m were measured at a helium
bath temperature of 1.8 K. | |
| 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. | |
| 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. | |