The Study Of Thermal-electric Problem Of High Power Millimeter-Wave Sheet Beam Device

With the development of microwave electronic systems,vacuum electronic devices need to advance towards high frequency,high power,high gain,wide band and miniaturization.The millimeter wave vacuum electronic devices can meet this demand.Its unique advantages make it has broad applications and important research significance in radar,communication,guidance,remote sensing of the earth,radiation measurement,medical examination,electronic countermeasures and other aspects.The Sheet Beam Extended Interaction Oscillator(SBEIO)can be flexibly applied to various airborne and spaceborne microwave weapons due to its small size.For SBEIO,the effect of thermal characteristics exists throughout the entire tube.As one of the basic components of SBEIO,sheet beam electron gun can produce sheet beam for its interaction with high-frequency electromagnetic field.The gun of SB-EIO equipped with a directly heated tungsten cathode operates at a high temperature(above 1000?).The thermal deformation of components of the electron gun happens inevitably in such a high temperature environment.However,the cathode and focusing electrode of the electron gun are very sensitive to the size change.If the deformation reaches a certain range,it will directly affect the quality of the electron beam resulting in a huge deviation from the ideal status of the emission trajectory.Therefore,the thermal and structural properties of the electron gun must be analyzed and estimated during the design process.The core component of SBEIO is the resonant cavity.During its operation,the wall current will lead to ohmic loss.In addition,the electrons intercepted by the wall will result in a high temperature rise on the cavity wall.The corresponding thermal deformation will have a great impact on the operating frequency,efficiency and output power of the resonator.Therefore,it is necessary to conduct effective heat dissipation on the resonator to make the device work stably.To sum up,the analysis of thermal-electric problem of the SBEIO is of great referential significance for the practical engineering production.In this paper,the thermal analysis of W-band SBEIO's electron gun and high frequency structure is mainly carried out.The main contents are as follows:1.Thermal analysis simulation and experimental test were carried out on the singlelayer thermo-substructure sheet beam electron gun.And an equivalent simulation method based on the experimental data is proposed.2.A three-layer folded thermosonic structure is studied,which can effectively improve the heating efficiency of the filament and reduce the thermal deformation of the electron gun.3.The influence of the thermal deformation of the cathode and the focusing electrode on the emission trajectory of the electron beam is analyzed.To correct the performance of electron beam to the desired state,the axial position pre-compensation and the application of the bias voltage of FE are studied.4.A heat dissipation structure combining jet and microchannel is proposed.The temperature distribution and pressure drop under different structure sizes are studied.The performance of the structure is compared with the traditional heat dissipation structure and the microchannel structure.5.The deformation analysis of the jet-microchannel structure is carried out.The cavity temperature is reduced and the thermal deformation is weakened by the structural modification.