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Abstracts Brochure - CERN

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TUPCH125<br />

TUPCH126<br />

TUPCH127<br />

TUPCH128<br />

27-Jun-06 16:00 - 18:00 TUPCH — Poster Session<br />

Development of the RF System for 150MeV FFAG Synchrotron<br />

Y. Yonemura (Kyushu University) M. Aiba, Y. Mori, C. Ohmori, K.<br />

Okabe, A. Takagi, M. Yoshii (KEK) R. Taki (GUAS/AS) M. Yoshimoto<br />

(JAEA/J-PARC)<br />

196<br />

Radio frequency acceleration system for the<br />

150MeV FFAG synchrotron has been developed<br />

at KEK. High electric field and broadband<br />

rf cavity is necessary to achieve a rapid<br />

cycling acceleration for the FFAG accelerator.<br />

In order to satisfy this requirement, the rf cavity using MA (magnetic alloy) core has been employed. We found that<br />

fringe field from the magnets at the straight section where the rf cavity was placed has reduced the shunt impedance<br />

largely. Moreover, the rf cavity became a source of COD because of coupling between fringe field and MA core. These<br />

problems have been resolved finally, and 100Hz operation was successfully realized.<br />

Outgassing Rate of Highly Pure Copper Electroplating Applied to RF Cavities<br />

T. Abe, T. Kageyama, Y. Saito, H. Sakai, Y. Sato, Y. Takeuchi (KEK)<br />

Z. Kabeya, T. Kawasumi (MHI) T. Nakamura, S. Nishihashi, K.<br />

Tsujimoto (Asahi Kinzoku Co., Ltd.) K. Tajiri (Churyo Engineering<br />

Co., Ltd.)<br />

We plan to apply a new copper electroplating<br />

with a high purity and a high electric<br />

conductivity to normal-conducting RF cavities<br />

for electron or positron storage rings with<br />

a high current beam. As reported in 2005<br />

Particle Accelerator Conference, our first test<br />

cavity, made of iron, with the electroplated copper surface finished up by electropolishing showed an excellent electric<br />

performance compared with the case of cavities made of oxygen free copper. Our next step is to examine the vacuum<br />

performance. This paper reports results of the outgassing-rate measurements on our second test cavity together with<br />

its fabrication process.<br />

Fine Grooving of Conductor Surfaces of RF Input Coupler to Suppress Multipactoring<br />

An RF input coupler to feed high power into<br />

T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi (KEK)<br />

an accelerating cavity with heavy beam loading<br />

undergoes many multipactoring zones<br />

due to the wide range of the input RF power. Furthermore, a regular coaxial line is more subject to multipactoring<br />

than a rectangular waveguide because of the uniformity of the electromagnetic field. Grooving the conductor surfaces<br />

of the coaxial line is a promising method to suppress multipactoring under any conditions expected in the above<br />

cases. This paper reports results of our multipactoring simulation study and the high power test of the input coupler<br />

with a grooved coaxial line.<br />

New Cutting Scheme of Magnetic Alloy Cores for J-PARC Synchrotrons<br />

C. Ohmori, S. Anami, E. Ezura, K. Hara, A. Takagi, M. Toda, M.<br />

Yoshii (KEK) M. Nomura, A. Schnase, F. Tamura, M. Yamamoto<br />

(JAEA/J-PARC)<br />

A new cutting method using a grindstone<br />

was developed to manufacture the magnetic<br />

alloy cores. The problem of local temperature<br />

rise around the cut surfaces was solved.

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