The results show that both of the growth rate of the TM01 mode are lager than those of the other modes. So the coaxial BWO will have a good property if it operates in the TM01 mode.

• 求解结果表明TM01模式的时间增长率和空间增长率的峰值与其它模式相比均是最大的,因此器件工作在TM01模式将会获得较好的输出结果。