The influence of anode-plasma location on total current in self-magnetically-limited electron-beam diodes

The critical current for both planar self-pinched electron-beam diodes and rod-pinch diodes is shown to be affected by the location of anode ion production relative to the cathode location. Specifically, for cathodes that are thin compared with the A-K gap, anode ions produced upstream of the cathode enhance the critical current scaling factor α. On the other hand, when ions are only produced downstream near the point where the electrons first hit the anode at grazing incidence, α approaches the electrons-only value. This new interpretation helps to bring PIC simulation results into better agreement with experimental results for both types of diodes.