激光电子散射中的最大可能增益

借鉴自由电子激光(FEL)发展之初Madey对自由电子激光器中受激辐射引起的增益的讨论，通过在激光场中的量子电动力学(QED)的模型中引入激光电子系统初态态密度以及由不确定的系统初态到确定光子末态的跃迁速率，推导了激光电子正碰过程中受激辐射至单一电磁模式产生的最大可能增益。采用成功得到X射线或$\gamma $射线光子的三个激光电子Compton背散射实验的实验参数计算了激光电子散射过程中的最大可能增益，与第一台X射线自由电子激光(XFEL)中的最大可能增益作比较，进而对激光电子散射作为激光光源的可行性进行评估。计算结果表明，现有的能够得到X射线光子或$\gamma $射线光子的激光电子散射实验中的最大可能增益远低于第一台XFEL中的。本工作未能找到合适的激光电子参数以获得比第一台XFEL中更高的最大可能增益，但是在入射电磁波位于射频波段范围内找到了能够实现较高增益的参数组合。

The Possible Maximum Gain in Laser Electron Scattering

Following Madey’s calculations on the possible gain induced by stimulated radiation in Free Electron Laser(FEL), we derive the possible maximum gain in laser electron scattering basing on Quantum Electrodynamic(QED) in laser field via introducing the initial state density of laser electron system and the transition rate into a definite final photon state in laser electron scattering. The parameters of laser electron scattering experiments where X-ray or $ \gamma $-ray photons were succesfully obtained are used to calculate the possible maximum gain in laser electron scattering, and the results are compared with that in the first lasing X-ray FEL(XFEL). The calculations show that if laser undulator FEL were built according to the existing experimental conditions in those laser electrons scattering experiments, the possible maximum gain would be much lower than that in the first lasing XFEL. While we have found appropriate parameters to achieve a relatively high gain when the wavelength of incident light is in radio frequency range.