双消色散270°偏转磁铁的物理设计

PHYSICAL DESIGN OF A 270°DOUBLE ACHROMATIC BENDING MAGNET

介绍了１４ＭｅＶ医用电子驻波直线加速器上所需用的２７０°双消色散偏转系统的物理设计过程与设计结果。系统的光路设计用ＴＲＡＮＳＰＯＲＴ程序计算，并且应用传输理论推导了双消色散满足的条件，两者结果一致；磁场计算利用ＰＯＩＳＳＯＮ程序完成，验证了磁铁中心磁感强度、好场区范围的场分布满足设计要求。此外，还研究了磁铁尺寸误差及安装误差对束流的影响，为工程设计和系统安装提供了依据。

The physical design of the 270°double achromatic bending magnet system is introduced for14MeV medical electron standing wave linac. The optical path design of the system is calculatedby the code TRANSPORT. Meanwhile,the double achromatism conditions are derived from thetransport theory, as a result they agree very well. From magnetic field of the magnet calculated bythe POISSON program, the magnetic field strength of the magnet center and the field distributionof the good field region both satisfy the design request. The influlence of fabrication error and mis-alignment of magnet on beam envelope is also considered here.