Study And Design Of Sheet Beam Extended Interaction Oscillator

Millimeter wave usually refers to the electromagnetic wave which covers the frequency from 30 GHz to 300 GHz(wavelength from 10 mm to l mm).Millimeter wave technologies are widely applied in communication,radar,electronic countermeasures,remote sensing and detection,etc.Millimeter wave vacuum electronic devices play an irreplaceable role in the field of national defense and military due to its high power,high frequency and miniaturization,and have been attached to many military powers.Sheet beam extended interaction oscillator(SBEIO)is outstanding in high-power and miniaturization,and is especially suitable for spaceborne and airborne microwave weapons.However,with the gradual enhancement of these advantages,the heat dissipation of sheet beam extended interaction oscillator is becoming more prominent.In high power condition,Because of the ohmic loss of high-frequency structure and the electronic interception on wall of the cavity,there will be a lot of heat.If the heat is not dissipated or is dissipated insufficiently,the high temperature on the wall may lead the cavity to be deformed,and even damage some components,which will affect the power capacity and stability of the whole tube.It is significant to study the heat dissipation structure and enhance the efficiency of heat dissipation for improving the power capacity and stability of the of sheet beam extended interaction oscillator.This thesis mainly studies the efficient cooling technology of a W-band sheet beam extended interaction oscillator,and a 4?-mode sheet beam extended interaction oscillator is designed.The main contents include the following aspects:1.The basic working principle of klystron and heat transfer mechanism is introduced.The heat source of SBEIO is analyzed,and the thermal analysis of high frequency structure of SBEIO is studied by loading heat source non-uniformly.The influence of phase transformation of water on heat dissipation is considered by the software FLUENT.2.The microchannel structure is studied for a SBEIO with high power capacity.According to the temperature distribution of the cavity,the number ratio of the flow channel is optimized.The influence of the channel size on the heat dissipation is studied,and the ladder structure is used to microchannel to improve the heat dissipation efficiency.The thermal deformation of the cavity is analyzed,and the change of the resonant frequency and output power after deformation is studied.The change of the power capacity is studied.The results show that the microchannel structure can greatly improve the power capacity of the SBEIO.3.The jet cooling structure is studied for a SBEIO with high power capacity.The heat dissipation structure of the high frequency structure is optimized,and the analyses of thermal and thermal deformation are also carried out.4.In order to achieve a W-band SBEIO with low voltage and high power capacity,a high frequency resonant cavity with 4π modes is proposed.The high-frequency resonant cavity working in 4?-mode has large longitudinal dimension relative to the cavity operating in 2?-mode,which can achieve low voltage operation and is conducive to the heat dissipation of high frequency structure.In this paper,the high-frequency resonant cavity working in 4?-mode is optimized.The particle simulation is carried out by PIC,and the feasibility of the resonant cavity working in 4-mode is verified.