Magnetic field measurement system for quick change of the cyclotron magnetic field

Okumura, Susumu; Miyawaki, Nobumasa; Yuyama, Takahiro; Ishizaka, Tomohisa; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Ishibori, Ikuo; Yuri, Yosuke; Nara, Takayuki; Yokota, Wataru; Fukuda, Mitsuhiro*; Nakajima, Tsukasa*

High-frequency change of beams accelerated for users is required at the JAEA AVF cyclotron, since the irradiation time is short in most cases and a large variety of beams is used. The ratio of the beam changing time to the whole operation time is not negligible and the offering machine time for users is half the required one. We are developing a technique for reducing the changing time of the magnetic field of the cyclotron, which dominates the beam changing time. Since a precise and stable magnetic field is required for acceleration in the cyclotron, especially for advanced beam applications, such as microbeam production, a magnetic field measurement system with a nuclear magnetic resonance (NMR) magnetometer was developed to monitor a wide range of magnetic field for acceleration of variety of beams in the JAEA AVF cyclotron.