Formation of a uniform ion beam using multipole magnets

多重極電磁石を用いた均一イオンビームの形成

百合 庸介; 石坂 知久; 湯山 貴裕; 奥村 進; 石堀 郁夫; 横田 渉; 渡辺 伸一*; 久保野 茂*; 大城 幸光*

Yuri, Yosuke; Ishizaka, Tomohisa; Yuyama, Takahiro; Okumura, Susumu; Ishibori, Ikuo; Yokota, Wataru; Watanabe, Shinichi*; Kubono, Shigeru*; Oshiro, Yukimitsu*

It is possible to fold the tails of the transverse beam profile into the inside, or even to uniformize the beam distribution in the properly-designed nonlinear beam transport system. A two-dimensionally uniform beam profile was formed using sextupole and octupole magnets at the azimuthally-varying-field cyclotron facility of Japan Atomic Energy Agency. Such a uniform beam enables us to perform uniform irradiation over the whole area of a large sample at a constant particle fluence rate, unlike the raster scanning system. Uniformization of heavy-ion beams as well as protons has been performed for the application of materials sciences. In order to reduce undesirable beam halos at the target, tail-folding of the spot heavy-ion beam is also planned using the nonlinear focusing method.