Ampfion hybrid diodes on Hydramite and PBFA-I

The Ampfion diodes are designed to have uniform behavior over the entire anode, and to generate ions efficiently by providing an insulating magnetic field which is enhanced by a series magnetic field coil[1–6]. In the Hybrid versions of this diode[2,4] the ions are supplied by surface-dielectric anodes like those used in other diodes. [7,8] In this presentation, three diodes will be discussed; a 20 cm focal length equatorial-feed or extraction diode for the 0.8 TW Hydramite pulser and 25 and 15 cm focal length polar-feed diodes for the PBFA-I pulser (∼10 TW at the diode terminals). The presentation will show progress toward the ultimate goals of high efficiency and small focus. More importantly, data will be presented which leads us to conclude that the diode is reasonably well understood. This includes data on the uniformity of the diode output, data showing the interaction of the relativistic electron cloud with the field coil, data showing the accuracy of focusing predictions, and other comparisons between data and theoretical modeling. One critical and poorly understood part of the diode is the anode. Anode turn-on delay will be discussed, along with the limitations it implies for our present technology.