Production mechanism of high proton ratio ion beam in the small arc discharge ion source

Morishita, Takatoshi; Iga, Takashi*; Inoue, Takashi; Imai, Tsuyoshi; Kashiwagi, Mieko; Shimizu, Takashi; Taniguchi, Masaki; Hanada, Masaya; Watanabe, Kazuhiro

A high proton ratio ( 90%) and a high current density proton beam is demanded in the International Fusion Materials Irradiation Facility (IFMIF). In the development of the beam source for nuclear fusion, it was indicated that the enhancement of the ion confinement using the large ion source is suitable for the increase in the proton ratio. In the beam source for accelerators, a single beamlet is enough to obtain a certain beam current, therefore, a small ion source is suitable from the aspect of efficiency and simplification of the system. To obtain the high proton ratio beam from the small ion source, it is necessary to grasp the production mechanism of proton. Then, the production process of the proton in the small ion source was investigated using rate equations. Obtained results were compared with experimental results. Consequently, although the proton is mainly produced from the molecular positive ions as considered conventionally, the production of the high proton ratio beam is also possible in the small ion source due to the effects of the magnetic filter.