.220 Ghz Gyrotron Research And Numerical Simulation Of The Mode Competition Theory

The gyrotron is based on the radiation which is excitated by electrons cyclotron resonance. It can operate on very high frequency ,especially at the millimeter and sub-millimeter wave band. And it can produce high output power in pulse and continuous wave. It can be used in plasma heating, accelerator, radar, communication, microwave weapon and so on .The THz radiation resource is one of the many important researching items in THz technique in recent years. THz is between the millimeter wave and the infrared, it is difficult to produce . But the application such as the radars and far distance detecting need great power THz resource. The gyrotron is the only device which can produce high great power THz wave up to now. The mode competition is very serious in THz gyrotron.We must overcome the mode competition to assure the gyrotron operating on single mode. The article adopts three multimode nonlinear theories to research the mode competition of a 220GHz gyrotron.First, the nonlinear multimode theory model based on the electrons kinetic equation is adopted, high frequency field equation and the energy balance equation is used to analyse the mode competition of a 220GHz gyrotron working on TE03 mode.Secondly, the multimode electrons kinetic equation, the normalized amplitude and the phase are deduced to develop the time-dependent nonlinear multimode theory model. And the theory has been developed along with a computer code to carry out the numerical calculations. The code is used to analyse the mode competition of a 220GHz gyrotron working in TE03 and a gyrotron working in TE_22,6. A contrast is carried out to the TE03 gyrotron with the calculations in former chapter. And the influence of the guiding centre and the magnetic field on mode competition of the TE_22,6 gyrotron is analysed .Thirdly, a space-time dependent nonlinear self-consistent multimode theory model is founded to analyse the mode competition of a 220GHz gyrotron working in TE_22,6.The multimode electrons kinetic equation and the normalized amplitude are deduced .