The coaxial gyrotron with two electron beams. I. Linear theory and nonlinear theory

The coaxial gyrotron with two electron beams (CGTB) is proposed and investigated in this paper. This paper consists of two parts: the linear theory and nonlinear theory of CGTB are presented in part I and the investigation on the dual frequency operation, a special operation state of CGTB, is given in part II. The magnetron injection gun with two electron beams has been developed, and simulations show that it may work well. It may guarantee that both the electric potential and the ratio of vertical to longitudinal velocities of two electron beams are equal. The results of the calculation show that CGTB has some distinguished advantages: mode competition is improved and output power is enhanced. Thus CGTB may be capable of providing 2 – 4 MW continuous-wave (CW) at 170 GHz to meet the demand of very high radio frequency CW power 1 – 2 MW in the ITER [ ITER EDA Agreement and Protocol 2 (IAEA, Vienna, 1994)] program and other applications.