Self-Consistent Effects of Space Charge Compensation on Intense Ion Beams

It is usually assumed that beams are partially space charge compensated for the design of high intensity, low energy beam transport. Such continuous beams are confined in space by means of magnetostatic lenses, the transverse matching into the RFQ accelerator being achieved with solenoids. Along this low energy transport, beam neutralization is kept almost constant, but severe problems can appear at the entrance of the RFQ where longitudinal bunching takes place. The electric field pulls out the neutralizing electrons, leading to a redistribution of the charged particles. We analyze theoretical solutions of this phenomenom in a self-consistent approach in view of minimizing emittance growth and halo development that could result.