Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization*

Plasmas are a source of unbound electrons for charge neutralizing intense heavy ion beams to allow them to focus to a small spot size and compress their pulse length. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length $\sim $ 0.1-1 m would be suitable. To produce one-meter-long plasma, sources based upon ferroelectric ceramics are being developed.$^{ }$ They can be scaled to large volumes and operate at low neutral pressures. The source utilizes the ferroelectric ceramic BaTiO$_{3}$ to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic, and high voltage ($\sim $ 5 kV) will be applied between the drift tube and the front surface of the ceramic. A prototype ferroelectric source 20 cm long has produced plasma densities of 5x10$^{11}$ cm$^{-3}$. It was integrated into the previous Neutralized Transport Experiment (NTX), and successfully charge neutralized the K$^{+}$ ion beam. Presently, the one-meter-long source is being fabricated. It will be characterized and integrated into NDCX for charge neutralization experiments.