分析了具有反射器的8 mm波段相对论绕射辐射振荡器，其高频系统为周期盘荷慢波结构，并且在电子注的输入端加有圆柱形同轴反射器。利用HFSS软件计算S11参数来确定反射器的结构尺寸。对该结构进行了PIC模拟，分析了该结构中注波互作用的非线性过程和反射器对该器件性能的影响。研究发现存在一个最佳反射器的位置，使注波互作用的效率高、频谱好。关 键 词 相对论绕射辐射振荡器; 反射器; HFSS软件; 粒子模拟Abstract A 8-millimeter-wave-band relativistic diffraction generator with a coaxial reflector is studied on this paper. High frequency system of the device is a slow-wave structure with a combination of rectangles and semicircles. A coaxial reflector is situated at the upstream entrance of the slow-wave structure. The parameter of reflector is obtained by calculating the S11 parameter by the software HFSS. The non-linear process of beam-wave interaction with the reflector is investigated on particle-in-cell (PIC) simulation. The result shows that there is the best location of the reflector, which makes the device have a maximum efficiency and single operation frequency.Key words relativistic diffraction generator; reflector; HFSS software; particle-in-cell simulation