Chaotic Behavior and Halo Development in the Transverse Dynamics of Heavy Ion Beams

This paper reviews results obtained from recent analytical and numerical investigations of chaotic behavior and halo development induced by charge density inhomogeneities in the transverse dynamics of heavy ion beams. In particular, a test-particle model is used to investigate the charged-particle dynamics in an intense, matched, heavy ion beam with nonuniform density profile propagating through an alternating-gradient quadrupole magnetic field in the space-charge-dominated regime. It is shown that self-field nonlinearities due to transverse nonuniformities in the beam density not only can result in chaotic ion motion but also can cause halo formation. For heavy ion fusion applications, these results indicate that accurate density profile control is critical in preventing heavy ion beams from developing halos.