| Paper | Title | Page |
|---|
| TUP39 | Basic Research on the 1.3 GHZ Superconducting Cavity for the ERL Main Linacs | 219 |
| | - T. Furuya, S. Sakanaka, T. Suwada, T. Takahashi, K. Umemori
KEK - H. Sakai, K. Shinoe
ISSP - M. Sawamura
JAEA
| |
| | Feasibility study of the superconducting cavity for 1.3
GHz ERL (Energy Recovery Linac) main linacs has
started under the collaboration of KEK, JAEA and
University of Tokyo. The development effort was
concentrated to optimize the cavity shape to sufficiently
suppress the beam instabilities for the desired accelerating
beam of 100 mA with the recovery beam of 100 mA. Our
final shape has a 9-cell structure with beam pipes of a
large diameter on both sides. BBU simulation on dipole
modes showed the BBU current limit of more than 600
mA without any randomize of HOM frequencies. HOM
power absorbed by the dampers is estimated as 100 W for
monopole modes. For the damping of quadrupole modes a
new idea of mode conversion using an eccentric fluted
beam pipe (EFB) is proposed and simulated. This simple
way can take out the quadrupoles to the beam pipe easily.
For the establishment of a manufacturing process and the
performance of the cavity shape, two single cavities one
of which has the EFB have been fabricated and measured.
Shape optimizing study, fabrication and some
measurement results will be presented. | |
| 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. | |