Simulation of injection and capture of beam electrons in small-size betatrons by the method of macroparticles

The simulation problem of self-consistent dynamics of electron beam in small-size betatrons has been considered. The description of numerical model developed on the basis of macroparticle method is presented. The results of process modelling of electron injection and capture on the acceleration mode in betatrons with axially-symmetrical and asymmetrical magnetic field are shown. Optimal input injection parameters by beam current and energy (20...40 keV and 0,1...1,0 А) providing the maximum number of the capture electrons are defined. The techniques of increasing capture efficiency due to using variations of external magnetic field and additional energy selection of circuital decelerating EMF of the captured electrons are numerically studied. It allows an increase in capture coefficient from 4 to 7,4 % and capture at the acceleration up to 7,4·1010 electrons