Halo formation induced by density nonuniformities in intense ion beams

Abstract

A test-particle model is used to investigate the charged-particle dynamics in an intense matched 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.