THE EMISSION AND TRANSPORT OF INTENSE RELATIVISTIC ELECTRON BEAMS

A 2-D CEBQ code in cylindrical geometry and a ENVLOP code used to simulate the emission and transport of intense relativistic electron beams in LIA are described in this paper. The CEBQ code simulates all electron trajectories in a diode considering effects of space charge and external electric and magnetic field. Poisson equation is solved with the finite element method suitable to complex boundary and clouds in-cell method is used to calculate charge deposition. The problem of β> 1 in numerical simulation is better overcome by using the conservation of canonical angular momentum. Two techniques are employed to improve numerical instability and to steep up the convergence of iteration: subrelaxation iteration for charge density and pervence. ENVLOP code calculates beam envelope in drift region in a linear approximation. We present the computed results for 1.5 MeV injector and discuss the effects of guiding magnetic field on beam envelope.