3-D particle simulations of applied-B ion diodes

Summary form only given. The 3-D particle-in-cell (PIC) code QUICKSILVER is being used for full 3-D simulations of an applied-B ion diode. The principal goal of the simulations is to investigate how inhomogeneities in the Ly-direction (corresponding to azimuthal variations in the cylindrical system) affect the stability of the diode, since linear analysis has indicated that instabilities are possible. Preliminary simulations have demonstrated a violent instability which rapidly saturates in only a few ion transit times. Near saturation of the instability, the onset of several phenomena is observed. First. one sees the growth of large variations of the ion current in the y-direction. Second, the energy spectrum of the beam passing through the gas cell foil broadens, and the beam divergence in the y -direction also grows. Finally, one sees electron loss to the anode, resulting in a diode efficiency of 85-90%