The Study Of The Noise In Traveling Wave Tube

Traveling Wave Tube belongs to Linear injection device.Compare to some other vacuum tube,it's output power is lower but long band.The usage of the tube is very wide.Most satellites use TWT as output amplifier.In most radar system,several TWTs will be used producing high frequency pulse.In addition,other electronic devices will require such as crossed-field amplifier's driver stage.Because of the electron emission randomness,electrons always first or late,fast or slow go in to the High frequency interaction area.This will produce noise,and affect the output power of the electronic devices and High frequency interaction area.This paper aim to make theoretical analysis and computer simulation,at the same time study TWT's noise producing mechanism,and ways to control it.This paper's main content below:1.The noise of travelling wave tube was analyzed during formation,movement,accumulation,growth and has a huge impact on the power.The explanations of the formation mechanism of the noise in the traveling wave tube has an important significance.Based on the one-dimensional linear model,and the data of the existing traveling wave tube was used to calculate the noise coefficient changes with distance,and study the influence of different parameters on the noise factor.2.In order to calculate the nonlinear macro particle simulation program,we set the initial status of the noise.Free electron laser macro particles mode and Maxwell speed distribution law were used to set initial noise.The pseudo random number was used to randomize macro particles.The noise set solution program was applied,also traveling wave tube standard equation was used to calculate one-dimensional nonlinear noise.Noise power spectral density was calculated at the same time.3.Two different frequencies of the helix TWT had been designed.One was 26-40 GHz and the other one was 33-40 GHz helix.Using HFSS software and TAU software,33-37 GHz output power was above 100 w,37-40 GHz output power was above 80 w.26-40 GHz TWT was aim to have maximum output power,thus the output power in all of frequency point was over 200 w.4.According to the design of the helix TWT data,2.5 dimension helix TWT noise power calculation program was developed,by modifying the original FORTRAN program,this program can also calculate the noise power spectral density of the helix TWT.Different parameters connected to the noise were explored,and the feasibility of the method and reduce the noise were proposed.