自由电子激光中电子与光子碰撞截面的特性

PROPERTY OF COLLISION CROSS SECTION OF A PHOTON AND AN ELECTRON IN THE FEL

自由电子激光中，相对论性电子与周期磁场的相互作用，可以看成电子场与光子场相互作用，而光子被散射．本文根据光子与电子的碰撞处理，计算了电子静止坐标系中光子的散射截面和总散射截面；再由多普勒效应，将电子静止坐标系变换到实验室坐标系，得出了相对论性电子与光子碰撞的散射截面的一般公式：．由此可知，微分散射截面与相对论的无量纲能量和散射角有关，说明了微分散射截面的各向异性．但当θ＝０°，即在电子的运动方向上探测散射光子，其散射截面最大．说明了电子是一个非常有效的散射体，这对进一步研究ＦＥＬ的机制具有重要意义．

in the FEL, interaction between relativistic electron and periodic magnetic field is regarded as interaction between electron field and photon field. In thispaper, according to the treatment of collision, calculate the scattering cross sectionof photon and the total scattering cross section in the static electron frame of reference. According to Doppler effect, the static electron frame of reference is turnedinto the laboratory system, thus we get the general formula of the scattering crosssection: This shows the differential scattering cross sectionis dependent of the relativistic dimensionless energy and the scattering angle. It illustrates the anisotropy of the differential sccattering cross section. However,when θ=0°, the scattering photon is detected on the moving direction, its scattering cross section is maximum. That illustrates that the electron is an effective scattering matter. It is a significance for further observation of mechanism of FEL.