线电荷串产生的史密斯帕塞尔辐射

Smith-Purcell Radiation from a Train of Line Charges with Reflection Grating

采用积分方法分析了线电荷串,沿周期性理想金属光栅表面平行移动时产生的史密斯帕塞尔辐射。分别对短周期光栅、低能量线电荷串与长周期光栅、高能量线电荷串的辐射情况进行了数值计算。相对单个线电荷而言,N个线电荷与反射光栅作用产生的辐射场密度,在频率是线电荷串调制频率的整数倍处出现最大,辐射谱宽变窄;随电荷能量增高,辐射能量向高频方向移动,并具有强烈的定向性;可以通过调节线电荷调制频率等参量实现辐射电磁波频率锁定。研究结果表明,对高能量与低能量的电荷参量,适当选择光栅尺寸与线电荷串间隔周期,都可使辐射波工作于太赫兹波段。

The Smith-Purcell radiation characteristic is analyzed from a train of line charges moving parallel to a sinusoidal metal reflection grating using an integral equation model. The numerical computations have been performed for short grating period with low-energy line charges and long grating period with high-energy line charges. The maximal radiated intensity is obtained at harmonics of the line charges modulating frequency. The bandwidth of the radiation becomes narrow, energy peaks are intensified. The normalized energy distribution produced by the high energy charges will have a narrow angular range emission peaks in the forward direction. The coherent radiation of frequency-locked will be generated gained from a train of line charges. The results show that the THz radiation will be produced for the reasonable parameters of line charge energy and grating.