Generation and focusing of high power ion beam in magnetically insulated diode with applied B-field

Abstract

High-power ion beam (HPIB) generation and plasma formation processes in a magnetically insulated diode (MID) installed at a 3*10/sup 10/-W nanosecond accelerator are reported. The possibility of efficient HPIB ballistic focusing using the performed plasma in the HPIB transport region has been demonstrated. Several new diagnostics (spring pendulum and acoustic probe) were used to measure the plasma ablation pressure during the impact of the HPIB with the target. The plasma formation and its behavior in the diode gap were studied by a high-voltage probe, array of collimated Faraday cups, and streak image converter. The electron losses at the anode played the dominant role in the MID impedance behavior. The application of the active plasma source provided control of the HPIB characteristics and MID impedance behavior. The highest degree of HPIB focusing attained during the experiments with spherical-geometry diode electrodes was equal to 60. The ablation average pressures measured by spring pendulum gave several kilobars for 8-10 kA/cm/sup 2/ of HPIB density. The peak pressures attained tens of kilobars for respective HPIB current amplitudes.<>