| Paper | Title | Page |
|---|
| WEP10 | Vertical test results on the STF baseline 9-cell cavities at KEK | 453 |
| | - E. Kako, H. Hayano, S. Noguchi, T. Shishido, K. Umemori, K. Watanabe, Y. Yamamoto
KEK - H. Sakai, K. Shinoe
ISSP, Univ. of Tokyo - S. I. Moon
POSTECH - Q. J. Xu
IHEP, CAS
| |
| | The STF-Baseline superconducting cavity system,
which includes four TESLA-type 9-cell cavities, input
couplers and frequency tuners, has been developed for the
future ILC project. A main improvement in the cavity
system is a very stiff design in a He vessel and a cavity
tuning system, which can relax a cavity deformation due
to Lorentz force. Making clear the performance level of
four 9-cell cavities, which were fabricated by a Japanese
company and were prepared by existent infrastructures at
KEK, is the most important purpose in the whole vertical
test. Total 14 vertical tests on four 9-cell cavities were
carried out repeatedly. The obtained Eacc,max in the final
performance was 29.4 MV/m in the #2 cavity, and the
others are 20.8, 20.5 and 20.2 MV/m, where the Qo
values higher than 1x1010 was achieved in all cavities.
Peculiar phenomena, like increasing of Qo values with
higher Eacc or very slow degradation of Qo values, were
observed in the vertical tests. Summary of the vertical test
results on four 9-cell cavities is described in this paper. | |
| WEP13 | Cavity diagnostic system for the vertical test of the baseline SC cavity in KEK-STF | 464 |
| | - Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, T. Shishido, K. Umemori, K. Watanabe
KEK - H. Sakai, K. Shinoe
ISSP, Univ. of Tokyo - S. I. Moon
POSTECH - Q. J. Xu
IHEP, CAS
| |
| | Four STF-Baseline superconducting cavities were
fabricated from 2005 to 2006. They were named BL1, 2,
3 and 4. The feature is that these cavities have the stiffer
structure than TESLA cavity. From Feb/2006 to Feb/2007,
the vertical tests were done totally 14 times at KEK.
These cavities were re-processed and measured
repeatedly. The surface treatment processes are composed
of Centrifugal Barrel Polish (CBP), Electro-Polish (EP)
and High Pressure Rinsing (HPR). And, HF or H2O2
rinsing were added as the additional process later.
In the vertical tests, a monitoring system was
introduced to search the heating spot on the equator and
to check the radiation level around the cavity. It is
composed of the carbon resistors and the PIN photo
diodes. They were attached on the equator of each cell
every 90 degree, a few resistors around the HOM couplers and a
few diodes on the top and bottom flanges of the cavity.
MX-100 (YOKOGAWA) for the carbon resistors and
NR-1000 (KEYENCE) for the PIN photo diodes are used
as the data logger. The sampling time is 100 or 200msec.
The heating spot was successfully observed during the
test. The appearance of that on the equator was coincident
with the quench of the cavity. On the other hand, the
diodes were useful for checking the presence or absence
of the field emission and they also were useful for
monitoring the radiation level during the RF processing.
The mapping display was introduced to identify the
location. Consequently, it is conceivable that the quality
of the electron beam welding was somewhat poor, when
the dumbbells were connected. | |