NUMERICAL MODELING OF AXISYMMETRICAL ELECTRON-BEAM DEVICES USING A COUPLED PARTICLE-FINITE ELEMENT METHOD

A coupled particle finite element method is developped for the numerical resolution of the time dependant relativistic Vlasov-Maxwell equations in axisymmetric geometries. The use of a conforming finite element method for the Maxwell solver supplemented with a mass-lumping technique leads to an explicit system for the computation of the electromagnetic fields compoments. For the Vlasov solver, a fully vectorized algorithm is used for the location of the particles in an unstructured mesh made up with triangles. The numerical values of the electromagnetic fields radiated by a dipole are compared with the analytical solution. The whole Vlasov-Maxwell solver is tested on a simplified free-electron laser electron injector, designed for an RF based free electron laser and the results are compared with those obtained with a finite difference code.