中文摘要：

采用等效媒质处理方法来研究有限引导磁场下沿纵向运动的相对论环形电子注.首先建立运动坐标系以电子注纵向速度匀速运动,在运动坐标系中电子注可以被考虑成静止的磁化等离子体,再通过四维空间的洛伦兹变换得到电子注在静止的实验室坐标系下可以被等效为双各向异性媒质,其不仅具有张量形式的电导率和磁导率,还具有手征特性.在此基础上同时考虑了由于电子注表面波动所引起的表面电流密度.采用该方法研究了有限引导磁场下圆柱波导中沿纵向运动的相对论环形电子注,推导出该模型的色散方程,并进行了数值计算.计算结果表明该研究方法能够得到更准确的信息,同时还得出对于沿纵向运动的相对论环形电子注,外部引导磁场可以通过电子注表面电流密度来影响电子注空间电荷波的色散曲线.因此等效媒质处理方法为研究相对论器件中注波互作用的热色散关系提供更为准确研究手段,这对于研究相对论电子学和相对论等离子体物理都是很有意义的.

英文摘要：

The relativistic annular electron beam guided by a finite axial magnetic field is studied in this paper,in which the electron beam is considered as a special media. Making use of the constitutive transformation and the Lorentz transformation in the four-dimensional space,the permittivity tensor of the stationary magnetized plasma,the permittivity tensor,the permeability tensor and the chiral tensor of the electron beam in the rest （laboratory） frame are acquired. And the boundary conditions,including the surface current density due to the ripple of the beam,have been obtained. As an example of the applications of this approach,the dispersion relations of a relativistic annular electron beam guided by a finite axial magnetic field in a waveguide has been studied. The results of numerical calculation show that the present approach is more accurate and can provide clearer mode information for the electron beam. In addition,the results also show the axial magnetic field can affect the dispersion curves of space charge wave via the surface current density of an electron beam. Thus this approach can be exploited in a number of electron beam-wave interaction systems,including some kinds of free electron devices,plasma filled Cherenkov radiated free electron lasers and masers.