Characteristics of beam phase in the JAEA AVF cyclotron

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

The characteristics of beam phase (BP) for three of acceleration harmonic modes (H=1, 2, 3) were investigated in the central region of the JAEA AVF cyclotron. Experiments were made to clarify relations of BP to the spatial displacements of ion beam orbits in the radial direction at the phase defining slit (PDS), and also to the initial condition of BP at the exit of the inflector defined by the phase shift of the beam bunching (BB). Some correlation of the BPs to both of the position of PDS and the phase shift of BB were observed in the case of H=1, but no correlation was found in the case of H=2. And in the case of H=3, only correlations of the intensity of the beam phase to them were observed with larger phase width than that in case of H=2. It is expected that optimization of the injection system and the central region of the cyclotron can be made according to these characteristics of BP depending on H, so as to obtain higher transmission of high quality ion beams.