自由电子激光辐射和迴旋辐射的比较研究

在自由电子激光器中一般存在两种受激辐射形式:自由电子激光辐射和迴旋辐射。本文从理论上阐明,如果电子束的初始横向速度较大,自由电子激光器的参数选用不当,则迴旋辐射将占优势,特别当电子束能量较低时,产生迴旋辐射的倾向更大。但是迴旋辐射并不具有双重多普勒频率上漂移的特性,由于受轴向磁场强度的限制,在电子束能量较高时,其辐射频率要比自由电子激光辐射频率低得多。因此在自由电子激光器的实验研究中,如何区别这两种辐射,并有效地抑制迴旋辐射,是一个十分重要的课题。

COMPARISON BETWEEN FEL AND CYCLOTRON RADIATIONS

In general, in free electron lasers there two kinds of stimulated radiations. FEL radition and cyclotron ralition. It is shown theoretically, if the initial transverse velocity of electron is large and the selected parameters for FEL are not suitable, the cyclotron radiation will be dorninant, especially when the energy of electron beam is low. But the cyclotron radiation does not have double Doppler frequency up-shift effect, is frequency is limited by axial magnetic field, when the energy of electron beam is high, the cyclotron radiation frequency ,will be much lower than FEL radiation frequency. Therefore, in FEL experiments how to disting-uish these two kinds of radiations and to suppress the cyclotron radiation are very important.