Applied-B field ion diode studies at 3.5 TW

The performance of 7 and 14 cm radius, applied B-field, focusing ion diodes is investigated on the Proto II accelerator at a diode power of 3.5 TW. The ion production efficiency of the 14-cm diode is determined to be approximately 80% for the 30-ns power pulse used. When a 2 Torr air background gas was used in the beam propagation region between the diode and the target, the ion beam was observed to be approximately 70% magnetically neutralized in regions of approximately 20 kG transverse B-field and ≥95% in regions of no B-field. The local and global divergence of the 1.4-MV beam were each determined to be approximately 1°. Local source power brightness of >1.5×1013 W/cm2/rad2 is inferred.