Researching On Focusing System Of Sheet Electron Beams Device In Millimeter Wave Band

Here the traveling wave device mainly refers to the TWT and the BWO.With the rapid development of microwave technology,the requirements of microwave devices are getting higher and higher.Various research institutions are toward smaller size,higher frequency,higher power and lower cost to research and development of microwave devices.Just right the sheet electron beams devices have such a performance,so more and more researchers pay attention to the sheet electron beams device,in recent years.The sheet electron beams devices is favored by the majority of researchers,mainly because the sheet electron beams have more advantages than the cylindrical electron beams:(1)The sheet electron beams can increase the current,without changing the input current density,by lengthening the lateral length of the cross section to increase in input and output power.(2)The sheet electron beam device narrow side of the smaller size to meet the high frequency wave wavelength requirements of the device size to be small this transition conditions.(3)The sheet electron beam device are closer to the inner surface of the slow wave structure,which facilitates the interaction between the electron beam and the high frequency structure.(4)The sheet electron beam device are easier to actually process and test.The sheet electron beam device also has many other advantages,but there are some problems need to be solved and optimized.For example,the horizontal charge field in the cross-section of the sheet electron beam is inconsistent with the horizontal and vertical directions,so focusing is difficult.In this paper,I combine Diocotron instability and space force of electron beam to design the focusing system of 140 GHz TWT and 220 GHz BWO.In this paper,TWT and BWO are focused by the permanent magnetic periodic magnetic field.The focusing system of the 140 GHz TWT is composed by the Wiggler system.Based on the analysis method of periodic permanent magnet focusing system,analyzing the magnetic field distribution of Wiggler magnetic field,and the condition of stable transmission of electrons is obtained by concretely solving the Mathieu equation.Based on the constraints of the Wiggler focusing system,the simulation results show that the Wiggler focus method can suppress the Diocotron and analyze,but the existence of lateral wobble and lateral diffusion in Wiggler system.The focusing system of the 220 GHz BWO make use of the periodic cusped magnetic focusing method.In this Paper,the magnetic field distribution of the PCM focusing system will be analyzed,and the PCM focusing system is designed according to the condition of the electron stable transmission.The simulation results are analyzed by simulation software CST modeling and simulating.PCM focus and Wiggler focus exist the same problem: electron beam transmission process in the lateral diffusion,electron beam output is wider than the width of input electron beam,it is about 3 times.In order to solve this problem,this paper by semi-infinite plane theory to establish the offset focus system offset_PCM.Under the action of offset_PCM focusing system,the simulation results of CST show that the sheet electron beams are stable to stable transmission,and the electron flow rate is 100%.