Progress of evaluation of beam coupling impedance reduction for the Eddy-current type septum magnet in J-PARC MR

Kobayashi, Aine*; Toyama, Takeshi*; Nakamura, Takeshi*; Shobuda, Yoshihiro; Ishii, Koji*; Tomizawa, Masahito*; Takeuchi, Yasunao*; Sato, Yoichi*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.19 - 23, 2023/01

https://www.pasj.jp/web_publish/pasj2022/proceedings/PDF/TUOB/TUOB01.pdf

In the J-PARC main ring, density modulation due to longitudinal beam instability occurs during the debunching process of coasting beams. This leads to the generation of an electron cloud, which in turn causes transverse beam instabilities. The transverse beam instability causes beam loss and the electron cloud is assumed to cause vacuum degradation, both of which hinder the beam intensity enhancement, so it is essential to clarify the causes and countermeasures. In particular, the longitudinal impedance of several hundred MHz has been investigated as relevant, and measures to reduce the impedance of individual devices are underway. The Eddy-current type septum magnet, newly installed this year, was found to have a large impedance by simulation. Therefore, we are investigating a method to reduce the impedance by a flange loaded with SiC radio wave absorber, which can be applied to locations where there is no spatial margin to install a taper. In this report, we will discuss the characterization of SiC to be used in actual devices, impedance simulation reflecting the results of SiC evaluation, and evaluation of the effect of impedance countermeasures by impedance measurement using the wire method, and progress in evaluating the effect on the beam by beam simulation and beam study.

RF dielectric properties of SiC ceramics at low temperatures

Takeuchi, Yasunao*; Sawamura, Masaru

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.597 - 601, 2014/06

http://www.pasj.jp/web_publish/pasj10/proceedings/PDF/SAP0/SAP059.pdf

no abstracts in English

Magnetic and Fermi surface properties of EuGa

Nakamura, Ai*; Hiranaka, Yuichi*; Hedo, Masato*; Nakama, Takao*; Miura, Yasunao*; Tsutsumi, Hiroki*; Mori, Akinobu*; Ishida, Kazuhiro*; Mitamura, Katsuya*; Hirose, Yusuke*; et al.

Journal of the Physical Society of Japan, 82(10), p.104703_1 - 104703_10, 2013/10

https://doi.org/10.7566/JPSJ.82.104703

Electronic states in antiferromagnet UCd and reference compound ThCd; Studied by the de Haas-van Alphen effect

Hirose, Yusuke*; Miura, Yasunao*; Tsutsumi, Hiroki*; Yoshiuchi, Shingo*; Oya, Masahiro*; Sugiyama, Kiyohiro*; Takeuchi, Tetsuya*; Yamagami, Hiroshi*; Yamamoto, Etsuji; Haga, Yoshinori; et al.

Physica Status Solidi (B), 250(3), p.642 - 645, 2013/03

https://doi.org/10.1002/pssb.201200765

Fermi surface and superconducting properties of non-centrosymmetric LaNiC

Hirose, Yusuke*; Kishino, Toshihiko*; Sakaguchi, Junya*; Miura, Yasunao*; Honda, Fuminori*; Takeuchi, Tetsuya*; Yamamoto, Etsuji; Haga, Yoshinori; Harima, Hisatomo*; Settai, Rikio*; et al.

Journal of the Physical Society of Japan, 81(11), p.113703_1 - 113703_4, 2012/11

https://doi.org/10.1143/JPSJ.81.113703