MODELING OF OSCILLATORY AND RETURN TRAJECTORIES OF ELECTRONS IN A GRADIENT MAGNETIC FIELD MAGNETRON GUN
DOI:
https://doi.org/10.32782/KNTU2618-0340/2021.4.1.14Keywords:
electron beam, magnetron gun, bifurcation, electron dynamics, gradient magnetic field, mathematical modeling, experimental dataAbstract
The motion of electrons in a cylindrical magnetic field with variable strength along the field axis is considered. Mathematical and numerical models of transformation of experimental data by analytical functions are used. In order to obtain precision characteristics, we studied the formation of a 55 keV beam in the longitudinal and radial directions during its transportation in the magnetic field of a solenoid. It is shown that the motion of electrons can be compared with an optical model of the transmission of light rays in a medium with a gradient coefficient depending on the radius. A software tool was developed, the use of which made it possible to simulate the main dependences of the motion of an electron beam in a given solenoidal magnetic field. The results of numerical simulation of electron trajectories in a gradient magnetic field of a magnetron gun with a secondary emission cathode are presented. The formation of a beam with energy of 55 keV in the radial and longitudinal directions during its transportation in a solenoidal magnetic field with a large gradient is considered. The operating modes of the gun are obtained in which the particle experiences the "bottleneck" effect and completes its movement by returning to the cathode region.. The influence of the initial conditions during emission on the occurrence of the return effect has been studied. It is shown that for a given electron energy and a fixed magnetic field, the parameter determining the particle reflection is the polar angle of entry relative to the axis of the cylindrical magnetic field. The dependence of the formation of the final distribution of particles on the amplitude and gradient of the magnetic field along the axis of the system is investigated. The results of numerical simulation on the motion of a tubular electron flow are presented. The possibility of controlling the longitudinal coordinate of the electron return point has been studied. The characteristics of the resulting electron beam are considered on the basis of a model of electron flow motion.
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