基于回旋管线性理论,运用Laplace变换和留数定理的方法,在线性Vlasov-Maxwell方程组的框架下,研究了特殊三反射镜准光腔回旋管的动力学理论.导出了注-波互作用功率、频偏和起振电流公式,运用MATLAB进行了数值运算.结果表明,这种回旋管工作于高次谐波状况下能有较高的互作用功率,具有工作于太赫兹波段的潜力. Based on the linear theory of convolute tube, the dynamics theory of the quasi-cavity gyroscope of a special triplet mirror was studied under the linear Vlasov-Maxwell equations using the Laplace transform and the residue theorem. Power, frequency deviation and starting current, and the numerical calculation is carried out by MATLAB.The results show that the gyro can work in the terahertz band with higher interaction power when it works in higher harmonic state.