COHERENT SMITH-PURCELL RADIATION IN THE MILLIMETER-WAVE REGION FROM A SHORT-BUNCH BEAM OF RELATIVISTIC ELECTRONS
COHERENT SMITH-PURCELL RADIATION IN THE MILLIMETER-WAVE REGION FROM A SHORT-BUNCH BEAM OF RELATIVISTIC ELECTRONS
复制标题
DOI：
10.1103/physreve.57.1061
复制
发表时间：
1998
影响因子：
2.4
通讯作者：
Y. Shibata;S. Hasebe;K. Ishi;S. Ono;M. Ikezawa;T. Nakazato;M. Oyamada;S. Urasawa;Toshiharu Takahashi;T. Matsuyama;K. Kobayashi;Y. Fujita
中科院分区：
文献类型：
--
作者：
Y. Shibata;S. Hasebe;K. Ishi;S. Ono;M. Ikezawa;T. Nakazato;M. Oyamada;S. Urasawa;Toshiharu Takahashi;T. Matsuyama;K. Kobayashi;Y. Fujita
在毫米波波段观测到了由150和40 MeV的短聚束电子通过薄片光栅产生的相干Smith-Purcell辐射。相干辐射的强度与束流的平方成正比，并且与普通Smith-Purcell辐射的理论强度相比，相干辐射的强度被增强了$\ensuremath{\sim}{10}^{8}$。增强因子与聚束中的电子数量具有相同的数量级。光强随光束高度或光束离光栅距离的增加而减小，对光束高度的依赖关系可用零阶修正贝塞尔函数近似表示。由于相对论效应，辐射沿着垂直于光栅的平面沿着窄方向发射。当光栅槽深变化时，辐射强度呈周期性变化。观测到的辐射特性很好地解释了史密斯-珀塞尔辐射的三维理论，其中的相干效应，由于聚束电子被考虑在内。
Coherent Smith-Purcell radiation, generated by the passage of short-bunched electrons of 150 and 40 MeV above a lamellar-type grating, has been observed in the millimeter-wave region. The intensity of the coherent radiation is proportional to the square of the beam current, and is enhanced by a factor of $\ensuremath{\sim}{10}^{8}$ in comparison with theoretical intensity of ordinary Smith-Purcell radiation. The enhancement factor is of the same order of magnitude as the number of electrons in a bunch. The intensity decreases with the increase of the beam height, or the distance of the beam from the grating, and the dependence on the beam height is expressed approximately by the modified Bessel function of the zeroth order. Owing to a relativistic effect the radiation is emitted in a narrow direction along the plane normal to the grating. The intensity of the radiation varies in a periodic way when the groove depth of the grating was changed. The observed properties of radiation are explained well by a three-dimensional theory of Smith-Purcell radiation, in which the coherence effect due to bunched electrons is taken into account.