Jun Tamura

A CS Installation for Beam Energy Upgrade in J-PARC Linac

The beam energy of the Japan Proton Accelerator Research Complex (J-PARC) linac has been increased from 181 to 400 MeV in January 2014. For the energy upgrade, the 25 Annular-ring Coupled Structure (ACS) cavities were installed in the beam transport at the downstream of the 191-MeV drift tube linac in 2013 maintenance period. To install and condition all the ACS cavities in a limited period of time, the upgrade of related systems such as a vacuum, magnets, RF, and cooling water has been started in 2010 and conducted in the annual maintenance period in every summer. This work includes the recovery efforts from the Tohoku earthquake in 2011. In this paper, the installation work for the energy upgrade and the related equipment for the ACS will be presented.

Improvement of Vacuum Pressure in the Annular-Ring Coupled Structures for the J-PARC Linac

The accelerating cavities of the J-PARC linac, additionally comprising an annular-ring-coupled structure (ACS), went into operation in 2014. To further improve the vacuum pressure of the ACS, an additional nonevaporable getter (NEG) pump was designed so that it could be installed independent of the vacuum chamber of the ACS cavity. We confirmed that the NEG pump can be appropriately activated by using a small pumping station and that purging with noble gases reduces the saturation of the NEG surface. In the evacuation test of the prototype ACS cavity with the NEG pump, the partial pressure of H2 and the total pressure were reduced from 4.8×10−7 and 6.8×10−7 Pa to 2.5×10−7 and 4.5 × 10−7 Pa, respectively. The additional NEG pump will be installed in the ACS cavity in the fall of 2014, after which any decrease in pressure and NEG-pump lifetime will be confirmed by long-term-operation experiments.

Upgrade and Operation of J-PARC Linac

Kazuo HASEGAWA*, Hidetomo OGURI, Takashi ITO, Etsuji CHISHIRO, Koichiro HIRANO, Takatoshi MORISHITA, Shinichi SHINOZAKI, Hiroyuki AO, Kiyonori OHKOSHI, Yasuhiro KONDO, Jun TAMURA, Saishun YAMAZAKI, Toshihiko HORI, Fumiaki SATO, Yasuo NEMOTO, Isao KOIZUMI, Nobuo OUCHI, Nobuhiro KIKUZAWA, Akira UENO, Akihiko MIURA, Shinpei FUKUTA, Akinobu YOSHII, Koichi SATO, Akira OZONE, Yuki SAWABE, Yusuke KAWANE, Hiroshi IKEDA, Yuichi ITO, Yuko KATO, Kazuo KIKUCHI, Fumio HIROKI, Toshio TAKAYASU, Tsutomu USAMI, Munetoshi YANAI, Kazuhiko TADOKORO, Kenji OHSAWA, Fujio NAITO, Yong LIU, Zhigao FANG, Takashi SUGIMURA, Kenta FUTATSUKAWA, Kiyoshi IKEGAMI, Masato KAWAMURA, Kesao NANMO, Yuji FUKUI, Tomoaki MIYAO, Tomofumi MARUTA and Akira TAKAGI