Simulation of an electron injection system used for medical linac In presence of the magnetic field

Electron injection systems are one of the foremost components of accelerators, which serves as a source of the electron beam. Linacs are widely used in the medical and industrial fields. However, most of these devices have to work in the presence of the magnetic field such as MRI linacs. The purpose of this work was to design of a triode structure (gridded) of Varian VTC6364 (diode gun) electron gun, based on the Vaughan method, and to analyze beam parameters in the presence of the magnetic lens. The theory and simulation of this method were investigated, and the gun model was developed by CST STUDIO commercial software. The performance and characteristics of the beam were analyzed in the different input voltage of the grid and lens current. Results of the simulation show that variation of the grid voltage cause changes in the beam current, perveance and beam waist position. Besides, the focal point of the electron gun shifts to the cathode under increment of the magnetic lens current. Changing in lens parameters also causes changes in the beam waist position and waist radius at both focal points

Keywords:

electron gun , magnetic lens , parametric simulations , accelerators