Hybrid ion diode theory and computations

Intense ion beams for inertial confinement fusion research are produced by diodes in which electron current is inhibited by strong magnetic fields. The insulating magnetic field in these diodes can be produced by the particle currents themselves or by an external field coil. The Hybrid ion diode incorporates a series field coil and a grooved epoxy filled anode to produce the pulsed ion beam. An extensive theory has been developed for this diode. [1,2] This theory has been applied in the design of three Hybrid diodes for use on the Hydramite and PBFA-I pulsers at Sandia National Laboratories. Both polar and equatorial versions of this diode concept have been tested. The design of these diodes will be discussed, including the description of various computer codes used in this process. The confirmation of various aspects of the theory for Hybrid diode operation will be discussed. A method for optimizing the diode focus will be described. A ray trace code has been written to investigate the focal properties of beams from these diodes and results will be given. Some particle-in-cell computations for specific diode designs will also be presented and compared with experimentally measured quantities.