Researches On Temperature Measurement Technology And Heat Dissipation Characteristics Of Slow-wave Structure Of Helix Traveling Wave Tubes

Helix traveling-wave-tubes(TWT)play an important role as microwave amplifier with wide-bandwidth,high power,and high efficiency,and now is being promoted to smaller size,higher power and higher reliability by development of military electronics industry.Slow-wave structure(SWS)is the key component of the energy exchange of helix TWT,which directly determines the performance of the whole tube.There will be a great heat flux on SWS when the helix TWT is in work,and this heat flux have to be dissipation through the rods and the shell outside the helix.Otherwise SWS will likely to be heat damaged.Therefore,contact thermal resistances between the three layers structures in SWS have a great influence on the reliability of the whole TWT.The electrical temperature measurement technology,based on electrical temperature sensitive parameters of semiconductor devices,can get the temperature changes by the changes of electrical parameters,has the advantages of fast,lossless and easy operation.In this paper,this method is applied to the measurement and research of the heat dissipation capability of SWS of helix TWT.And a set of thermal resistance test device of SWS of helix TWT is designed.The research mainly completed the following aspects:1.Based on forward voltage,the electrical temperature sensitive parameter of Schottky diode,a thermal resistances test instrument has been developed for SWS of helix TWT.The instrument mainly divided into computer software and hardware control circuit.The function of the computer software is mainly to control the hardware circuit through parameters input by users,and to calculate the measured data.And the hardware control circuit is mainly apply power to Schottky diodes and collect changes in junction voltage under the control of software.2.In order to apply the electrical temperature measurement technology used in semiconductor device to microwave device,a special thermal resistance test probe is designed to match the millimeter and sub-millimeter size of helix SWS.In measurement process the heat of the diode will conduct through the three layers of SWS and finally dissapated into atmospheric environment.In this way,the reflection from diode junction voltage changes to capacity of SWS has been achieved.3.Capacity of SWSs with helix diameter of 1.5mm,1.8mm and 2.5mm is tested utilizing the thermal resistances test instrument.The software of instrument processed the changes of Schottky junction voltage measured by hardware circuit and then the transient temperature rise response curve of Schottky junction was obtained.Furthermore,according to the structural function method,thermal resistance structure differential curve that can directly read the thermal resistance of each layer along vertical dissipation path was obtained.Finally,measurement and analysis of heat dissipation performance of SWS are realized.