Pic Code Simulations of Collective Effects in the Space- Charge-dominated Beam of the University of Maryland Electron Ring (umer)

Numerical simulation using particle-in-cell codes is a powerful tool in understanding the nonlinear dynamics of space-charge-dominated beams. The University of Maryland Electron Ring (UMER) will explore the transport of beams with intensity previously inaccessible to circular machines. The ring will also function as a testbed for accelerator codes. Applications such as heavy ion fusion and colliders require the preservation of beam quality during transport over large distances. This need for low beam emittance and small particle losses constrains the design and fabrication of the lattice and the injector. Furthermore, the non-zero energy spread leads to dispersion in the circular lattice. Simulations using the WARP code address these issues: the magnets, including the fringe field nonlinearities, are modeled realistically; dispersion matching is attempted; and effects of lattice and beam errors are examined. The simulations aid in understanding experimental results, such as the transverse density waves observed in the injector.