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.

• Received 21 February 1995

DOI:https://doi.org/10.1103/PhysRevE.51.R5216