Abstracts Brochure - CERN

TUPCH125
TUPCH126
TUPCH127
TUPCH128
27-Jun-06 16:00 - 18:00 TUPCH — Poster Session
Development of the RF System for 150MeV FFAG Synchrotron
Y. Yonemura (Kyushu University) M. Aiba, Y. Mori, C. Ohmori, K.
Okabe, A. Takagi, M. Yoshii (KEK) R. Taki (GUAS/AS) M. Yoshimoto
(JAEA/J-PARC)
196
Radio frequency acceleration system for the
150MeV FFAG synchrotron has been developed
at KEK. High electric field and broadband
rf cavity is necessary to achieve a rapid
cycling acceleration for the FFAG accelerator.
In order to satisfy this requirement, the rf cavity using MA (magnetic alloy) core has been employed. We found that
fringe field from the magnets at the straight section where the rf cavity was placed has reduced the shunt impedance
largely. Moreover, the rf cavity became a source of COD because of coupling between fringe field and MA core. These
problems have been resolved finally, and 100Hz operation was successfully realized.
Outgassing Rate of Highly Pure Copper Electroplating Applied to RF Cavities
T. Abe, T. Kageyama, Y. Saito, H. Sakai, Y. Sato, Y. Takeuchi (KEK)
Z. Kabeya, T. Kawasumi (MHI) T. Nakamura, S. Nishihashi, K.
Tsujimoto (Asahi Kinzoku Co., Ltd.) K. Tajiri (Churyo Engineering
Co., Ltd.)
We plan to apply a new copper electroplating
with a high purity and a high electric
conductivity to normal-conducting RF cavities
for electron or positron storage rings with
a high current beam. As reported in 2005
Particle Accelerator Conference, our first test
cavity, made of iron, with the electroplated copper surface finished up by electropolishing showed an excellent electric
performance compared with the case of cavities made of oxygen free copper. Our next step is to examine the vacuum
performance. This paper reports results of the outgassing-rate measurements on our second test cavity together with
its fabrication process.
Fine Grooving of Conductor Surfaces of RF Input Coupler to Suppress Multipactoring
An RF input coupler to feed high power into
T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi (KEK)
an accelerating cavity with heavy beam loading
undergoes many multipactoring zones
due to the wide range of the input RF power. Furthermore, a regular coaxial line is more subject to multipactoring
than a rectangular waveguide because of the uniformity of the electromagnetic field. Grooving the conductor surfaces
of the coaxial line is a promising method to suppress multipactoring under any conditions expected in the above
cases. This paper reports results of our multipactoring simulation study and the high power test of the input coupler
with a grooved coaxial line.
New Cutting Scheme of Magnetic Alloy Cores for J-PARC Synchrotrons
C. Ohmori, S. Anami, E. Ezura, K. Hara, A. Takagi, M. Toda, M.
Yoshii (KEK) M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
(JAEA/J-PARC)
A new cutting method using a grindstone
was developed to manufacture the magnetic
alloy cores. The problem of local temperature
rise around the cut surfaces was solved.