Abstract
A new model of relativistic Applied-B ion diodes is presented that appears to explain a previously discovered empirical scaling law. The model is based on a self-consistent calculation of the diamagnetic effect of virtual-cathode location coupled with the assumption of a uniform electron-density profile in the sheath. The success of this model greatly increases our understanding of the undesirable phenomenon of impedance collapse in applied-B diodes and suggests a simple measure for improving their performance.