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Journal Articles

Momentum loss during slow extraction in the J-PARC MR and its countermeasures

Tamura, Fumihiko; Yamamoto, Masanobu; Omori, Chihiro*; Yoshii, Masahito*; Schnase, A.*; Nomura, Masahiro; Tomizawa, Masahito*

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.125 - 129, 2014/06

For the slow extraction in the J-PARC MR, the rf voltage ins the cavities is turned off after finishing the acceleration to obtain a coasting beam. During the debunching process, the average momentum decrease due to the longitudinal coupling impedances in the MR. The decelatation continues until a well debunchedbeam is foarmed. The deceraration causes a reduction of the extraction efficiency due to the chromatic effects. In the J-PARC MR, a momentum loss has been observed at a relatively low beam power. To achieve higher beam power with keeping the high extraction efficiency, measures against the momentum loss are necessary. In this article, we report the observations and simulation results of the momentum losses. We adopt the rf feedforward method to cancel the wake voltage in the cavity as a measure of the momentum loss. By the feedforward, the momentum loss is significantly reduced. We achieve a high extraction efficiency, 99.5%, at the beam power of 20 kW.

Journal Articles

J-PARC MR horizontal exciter test for transversal noise application

Schnase, A.; Sato, Kenichiro*; Tomizawa, Masahito*; Toyama, Takeshi*; Uota, Masahiko*; Yoshii, Masahito*

Proceedings of 8th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.338 - 342, 2011/08

Journal Articles

Simulation of narrow-band longitudinal noise applied to J-PARC Main Ring

Schnase, A.; Tamura, Fumihiko; Koseki, Tadashi*; Tomizawa, Masahito*; Toyama, Takeshi*; Yoshii, Masahito*; Omori, Chihiro*; Nomura, Masahiro; Yamamoto, Masanobu; Toda, Makoto*; et al.

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1079 - 1081, 2010/08

Journal Articles

Application of digital narrow band noise to J-PARC Main Ring

Schnase, A.; Tamura, Fumihiko; Koseki, Tadashi*; Tomizawa, Masahito*; Toyama, Takeshi*; Yoshii, Masahito*; Omori, Chihiro*; Nomura, Masahiro; Yamamoto, Masanobu; Toda, Makoto*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1446 - 1448, 2010/05

Journal Articles

Beam injection tuning of the J-PARC main ring

Wei, G.; Koseki, Tadashi*; Igarashi, Susumu*; Tomizawa, Masahito*; Takano, Jumpei*; Ishii, Koji*; Shirakata, Masashi*; Fan, K.*; Hatakeyama, Shuichiro; Uota, Masahiko*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3915 - 3917, 2010/05

Journal Articles

Beam fast extraction tuning of the J-PARC main ring

Wei, G.; Koseki, Tadashi*; Tomizawa, Masahito*; Igarashi, Susumu*; Ishii, Koji*; Ando, Ainosuke; Takano, Jumpei*; Uota, Masahiko*; Fan, K.*; Hatakeyama, Shuichiro; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3918 - 3920, 2010/05

Oral presentation

Physics design and commissioning experience of J-PARC main ring injection and extraction

Wei, G.; Koseki, Tadashi; Igarashi, Susumu*; Takano, Jumpei*; Tomizawa, Masahito*

no journal, , 

Oral presentation

Refining narrow-band noise signals for transversal beam excitation to improve J-PARC MR slow extraction

Schnase, A.; Tamura, Fumihiko; Tomizawa, Masahito*; Toyama, Takeshi*; Yoshii, Masahito*

no journal, , 

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