An Automatic Magnetic Field Measurement System For Traveling Wave Tube

Traveling Wave Tube(TWT)has become the most widely used microwave amplifier in the fields ofin characteristics.Its working principle is to use electronic beam to transfer its o radar,communication,electronic countermeasures,etc,due to its wide frequency band and high ga wn energy to microwave signals to realize signal amplification.However,there is a spatial repulsive force between electrons.If electrons are not constrained,TWT will inevitably be burned.The TWT magnetic system is used to focus the electrons,which directly affects the power,bandwidth,and stability of TWT.It is of great significance to measure the distribution of axial magnetic field intensity of the magnetic system,whether in the design stage or in the production and assembly stage.The traditional method of measure manual magnetic field intensity measurement method adopted by domestic TWT manufacturers has some problems,such as low measuring accuracy,long testing time and low testing efficiency.Therefore,it is very important to develop a set of practical automatic measurement system for axial magnetic field intensity of TWT magnetic system to solve the above problems.In this paper,the research progress of magnetic field measurement methods for TWT permanent magnet system at home and abord is deeply studied,and the advantages and disadvantages of various magnetic field measurement methods are analyzed.On the basis of manual measurement,combined with the existing conditions of the laboratory.the design scheme for the automatic system of TWT magnetic system is determined.The scheme is mainly divided into hardware system and software system.The hardware system includes data acquisition subsystem,motion control subsystem,fixture subsystem and data processing subsystem.At the same time,according to the needs of data acquisition,a set of alignment subsystems for axial centering of probes and magnetic systems is designed.The software system includes motion control module,user management module,data acquisition and display module,measuring result processing module and so on.This subject takes virtual instrument technology as the core,and the development and debugging of software are based on Labwindows/CVI and its function library.In order to realize the position control of the electronic control translation table and the data acquisition control of the probe,the testers input motion control parameters on the test software,and the software automatically generates control commands and sends them to the instrument through serial port.During the measurement process,the software panel will display the information about position and the magnetic field in real time.After the measurement,the software will automatically output the 2D curve of the magnetic field intensity varying with the position.In addition,all test information will be automatically saved on the computer for users to view and call.At last,the subject makes an actual measurement of an experimental sample and imports the measurement result into the microwave tube simulation software MTSS.Furthermore,the numerical simulation of beam-wave interaction is carried out by using MTSS and measured magnetic field data,and then the result is compared with the situation of the external theoretical magnetic field to complete the error analysis.The experimental results show that the automatic measurement system of TWT axial magnetic field developed in this paper works stably.The measurement results are accurate and efficient,and are of great significance to improve the production efficiency,save evelopment cost and improve performance of TWT.