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Journal Articles

Challenge to charge exchange with pure carbon foil in the J-PARC 3GeV synchrotron

Nakanoya, Takamitsu; Yoshimoto, Masahiro; Saha, P. K.; Takeda, Osamu*; Saeki, Riuji*; Muto, Masayoshi*

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.937 - 941, 2023/11

https://www.pasj.jp/web_publish/pasj2023/proceedings/PDF/FRP3/FRP38.pdf

In the J-PARC 3GeV Rapid Cycling Synchrotron (RCS), the 400MeV H $^{-}$ beam is changed to H+ beam by a charge exchange foil and accelerated to 3GeV. So far, RCS had used two types of charge exchange foil. One is the HBC (Hybrid Boron mixed Carbon) foil and the other is the Kaneka GTF (Graphene Thin Film). HBC foil is a patented deposition method developed at KEK for the stable production of thick carbon foil. Initially, the RCS used HBC foil produced atKEK. However, in 2017, JAEA had started HBC foil production and has been using it since then. Recently, we have succeeded in depositing thick pure carbon foil, which had been considered difficult to produce by the arc deposition method. As a new challenge, this pure carbon foil was used in the user operation from March 2023. As a result, Pure carbon foils showed less deformation and more stable charge exchange performance than HBC and GTF.

Journal Articles

Fabrication status of charge stripper foil for 3 GeV synchrotron of J-PARC

Nakanoya, Takamitsu; Yoshimoto, Masahiro; Yamazaki, Yoshio; Takeda, Osamu*; Saeki, Riuji*; Muto, Masayoshi*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.545 - 549, 2019/07

In the 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research complex (J-PARC), we adopted the carbon stripper foil for the multi-turn H- charge exchange injection. The charge exchange foil which use in RCS is fabricated by the arc discharge method with the boron doped carbon electrode. The foil fabricated this method is called HBC foil (Hybrid Boron mixed Carbon stripper foil). HBC foil had been developed at KEK. It has high durability for the beam irradiation damage. In past days, the foil fabrication process was conducted in KEK Tsukuba-site and the foil preparation process was conducted in JAEA Tokai-site. In 2017, the foil deposition apparatus has been relocated from KEK to JAEA, and we started both processes in Tokai-site. We carried out the offline beam irradiation test for the new HBC foil which fabricated in JAEA, and we confirmed that its performance is equivalent to the original HBC foil. Next we tested a new HBC foil with actual beam in RCS and we confirmed it could withstand 1 week beam irradiation. After that, we started user operation with the new HBC foil in 2018. So far we accomplished stable user operation for one year by using the new HBC foil only.

Journal Articles

Analysis of carbon thin films by laser Raman method

Kinsho, Michikazu; Kamiya, Junichiro; Koizumi, Oji*; Nasu, Shogo*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.668 - 670, 2018/08

https://www.pasj.jp/web_publish/pasj2018/proceedings/PDF/WEP1/WEP117.pdf

Crystallinity, crystalline structure and internal force of thin films were measured by Laser Raman spectroscopy for the purpose of analyzing the fracture mechanism of the charge exchange foil due to beam hitting in this study. Thin films were used four types of HBC foil, pure carbon film (C foil) formed by arc discharge method, graphene, and carbon nanotube (CNT foil). As a result of changing the laser output and measuring the Raman peak shift of each foil, the HBC foil and the C foil had large Raman peak shift change, the D-band was negative and the G-band was opposite sign with positive. On the other hand, the graphene and the CNT foil showed small change in Raman peak shift, and both D-band and G-band were negative. From these results, it was found that a large stress occurs in the HBC foil and the C foil due to the heat load by the laser which was used for Raman spectrum measurements.

Journal Articles