建立在Boltzmann方程基础上的高能电子输运Fermi－Eyges理论

THE FERMI-EYGES THEORY FOR HIGH-ENERGY ELECTRON TRANSPORTESTABLISHED ON THE BASIS OF BOLTZMANN EQUATION

以高能电子在多成分介质中穿透的Ｂｏｌｔｚｍａｎｎ方程为基础，用严格的输运理论方法重新导出了广泛用于电子束剂量算法中的Ｆｅｒｍｉ－Ｅｙｇｅｓ理论。新的推导方法给予Ｆｅｒｍｉ－Ｅｙｇｅｓ理论更加坚实的物理基础和更为清晰的物理图象，指出了该理论中所存在两个主要问题的根源所在，从而为解决问题提供了新的途径。此外，在推导过程中还发现，Ｆｅｒｍｉ－Ｅｙｇｅｓ理论中表征电子多次散射过程的量应是平均广义散射本领，而不是通常所用的散射本领。

in the present paper,on the basis of Boltzmann equation for high-energy electronspenetrating in multi-constituents media , the Fermi-Eyges theory , which has been widely applied in theelectron beam dose algorithms ,is obtained by means of strict transport theory method. The new methodshows more solid physical foundation and more distinct physics image of the Fermi-Eyges theory,andpoints out the canse of the two main problems existing in the theory ,then provides new ways for thesolution of the problems. Fourthermore, it is found that the parameter which deecribes the multiplescattering of electrons in fhe Fermi-Eyges theory should be mean generalized scattering power ,not theusual scattering power.