Warp has extensive provisions to define lattice elements which generate applied fields to focus, accelerate, and bend the beam (and/or the coordinate system). Most classes of lattice elements have many possible options and are compatible with both ring (multiple pass) and linear (single pass) architecture machines by setting appropriate periodicity conditions. Features of lattice elements such as apertures can be passed to the field solver when some (but not all) field solvers are used so correct boundary conditions are employed in calculation of beam self-fields. In the links below we cover, in turn, how to add lattice elements to describe most any applied field structure, how to add gridded field data, and how to make lattice elements time varying.
Adding lattice elements covers the basic methodology. Gridded field data provides more information on how to setup applied field elements with gridded field data that might be imported from various design codes or measurements, and time dependant lattice elements provides details on how essentially any lattice element can be made time varying. Time varying elements can be used to model rf cavities or pulse power driven induction gaps used to accelerate the beam.