Operation of a 120-MW ion beam source using an Applied-Bθ ion diode

The operation of an Applied-Bθ ion diode has been studied at voltages up to 1.8 MV and diode currents of 250 kA. Peak ion currents up to 80 kA were observed at diode current efficiencies of up to 33% during the 60 ns power pulse. Ion and electron flow patterns have been carefully measured which indicate electron loss at locations far removed from the anode-cathode gap and ion current density enhancement at the inner anode radius due to motion of the cathode electron sheath. Numerical simulations performed with particle-in-cell codes agree well with the experimentally determined diode parameters including electron dynamics and ion and electron fluxes.