Producion of intense focused ion beams in a spherical magnetically insulated diode

Abstract
A magnetically insulated ion diode has been constructed with a spherically focusing geometry. The diode has been operated at voltages of ∼250 and ∼500 kV, with impedances adjusted to 2–3 and 7–10 Ω, respectively. The pulse length was ∼85 ns. Total ion currents were ?30% of the diode current. In the high‐voltage case, a focal current density of 2100 A/cm2 was obtained; this is ≳90 times the anode ion current density. Auxilliary magnetic fields were used to steer the beam, with the beam deflection as calculated for a single proton. The diode design and diagnostic techniques are described, as well as possibilities for improvements suggested by our data.