PROBLEM TO BE SOLVED: To provide a particle accelerator capable of suppressing deformation in a beam shape of a charged particle beam, and a beam shape adjusting method for the charged particle beam.SOLUTION: A particle accelerator comprises: a pair of disc-shaped magnetic poles 10A including multiple hills 11 and multiple valleys 12 which are disposed so as to face each other with an acceleration plane where a charged particle is accelerated, interposed therebetween and alternately provided in a circumferential direction； a foil stripper which emits a charged particle beam from the outside of the magnetic poles 10A in a radial direction in a region where the hills 11 face each other； and multiple shims 16 attached to side faces of the multiple hills 11 crossing each other in the circumferential direction. In a region R within a predetermined distance from a center C of the acceleration plane, a thickness T of a shim 16 attached to one hill 11 and a thickness T of a shim 16 attached to the other hill 11 facing the one hill 11 with the center C of the acceleration plane interposed therebetween are different from each other.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2020,JPO&INPIT【課題】荷電粒子線のビーム形状の変形を抑制することが可能な粒子加速器、及び、荷電粒子線のビーム形状調整方法を提供する。【解決手段】粒子加速器は、荷電粒子が加速される加速平面を挟んで互いに対向するように配置され、周方向に交互に設けられた複数のヒル１１及び複数のバレー１２を有する一対の円板状の磁極１０Ａと、ヒル１１が対向する領域において、磁極１０Ａの径方向の外側から荷電粒子線を出射させるフォイルストリッパーと、周方向に交差する複数のヒル１１の側面に取り付けられた複数のシム１６と、を備え、加速平面の中心Ｃから所定距離内の領域Ｒにおいて、一のヒル１１に取り付けられたシム１６の厚さＴと、加速平面の中心Ｃを挟んで一のヒル１１と対向する他のヒル１１に取り付けられたシム１６の厚さＴとは互いに異なる。【選択図】図３
