3-D studies of the formation and stability of strong ion rings

We are engaged in conducting complex, 3-D simulations in support of the on-going experimental program, FIREX (Field-Reversed Ion Ring Experiment) launched at the Cornell University to produce an ion ring magnetic field-reversed configuration by injecting an intense annular proton beam across a plasma-filled magnetic cusp region into a neutral gas immersed in a ramped solenoidal magnetic field. Our previous axisymmetric PIC simulations performed with the. FIRE code have demonstrated that strong ion rings (with a self-magnetic field large enough to reverse the applied field on axis) can be created using this technique on the equipment designed and assembled at Cornell. We have created a new, parallel, object-oriented, 3-D, hybrid, PIC code, FLAME to study questions of extreme importance to the success of the FIREX program, namely, the 3-D injection of a powerful ion beam into a strongly magnetized plasma, formation of a field-reversed ring, and the stability, and equilibrium of such rings to toroidal perturbations. Using FLAME we have investigated the stability of the ring formation during the injection phase and at later times when the ring is virtually stopped and the applied magnetic field is nearly reversed. Our simulations have revealed the effect of toroidal aberrations in the axially ramped magnetic field on the ion ring formation.