Time dependent measurements and calculations of field profile in the PBFA-II ion diode

Summary form only given. The reduction of the effective anode cathode (AK) gap during an applied-B ion diode pulse is driven by the diamagnetic effect of E/spl times/B drifting electrons in the sheath between the virtual cathode and the anode, and may be assisted by fluctuations that enable electrons to cross magnetic field lines. The dynamics of the sheath and the resulting AK gap are manifested in the time and space dependence of the electric field across the gap. The authors are studying the electric field profile in the PBFA-II (particle beam fusion accelerator II) ion diode with the goal of improving the understanding of acceleration gap dynamics, leading to improved power coupling to the ion beam. The field profile measurements have been compared with calculations performed using two different computer codes QUICKSILVER and TWO-QUICK.