Magnetic-field extraction and filamentation of high-current electron beams

Beam extraction simulations for high-voltage, immersed source accelerators are compared with analytic theory and experiment. dynadIsc, a new nonlinear beam propagation code, is described and applied to the initial few meters of propagation in 1 atm air. The dynadIsc results indicate that filamentation is the fastest growing instability. The filamentation changes the beam current density profile from an annular to a quasi-uniform distribution