Theory for the Magnetic Particle–Field Interaction, Relativistic Interface
The Particle–Field Interaction, Relativistic Interface combines the Charged Particle Tracing, Electrostatics, and Magnetic Fields interfaces to model relativistic beams of charged particles that can create significant space charge density and current density distributions in the domains that contain the particles. The space charge density may, in turn, exert a significant electric force on the particles, whereas the current density contributes to the magnetic field in the surrounding domains, exerting a magnetic force on the particles.
If all charged particle beams are released at constant current, it is possible to significantly reduce the simulation time and computational cost by combining a time-domain calculation of the particle trajectories with a Stationary solver for the calculation of the electric potential and magnetic vector potential. The two calculations can then be performed using an iterative procedure that alternates between them until a self-consistent solution is attained.
An iterative solver loop that consists of a time-dependent solver for computing particle trajectories and a stationary solver for computing all other dependent variables can be set up automatically using the Bidirectionally Coupled Particle Tracing study step, described in the COMSOL Multiphysics Reference Manual.