The virtual particle EM PIC method for modelling microwave devices

Further developments and applications of the virtual particle (VP) PIC algorithms are presented. The schemes are obtained by minimizing the Maxwell-Vlasov action integral after it has been approximated using finite elements in both space and time. The algorithms are energy and charge conserving, even for finite timestep. The main difference from conventional PIC schemes is that current is assigned from virtual particles placed at specially selected points in time on particle orbits. It is this feature which leads to exact charge conservation. Results presented show that the advantages of the VP method carry over into general curvilinear coordinates. The problems of efficiently treating electron emission and EM power extraction are discussed, and simulation results from a cylindrical implementation of the VP method are given