Focusing studies of an applied Br extraction diode on the LION accelerator

The LION Accelerator, 1.5 MV, 4Ω, is being used to study the characteristics of an applied B_r extraction diode. The diode utilizes both an inner and outer cathode and has been observed to operate at high ion current efficiencies compared to previous extraction diodes. Typical efficiencies were measured to be ≈ 80% which compare very favorably with the efficiencies seen in applied B_z diodes. Here we report the results of a series of experiments examining the role of the inner cathode in electron loss and ion emission. In addition, operation with an argon gas cell is reported. The ion beam appears to be space-charge neutralized by the gas cell foil alone, and current neutralized when the gas cell pressure is above 100mT.