Moderate energy metal ion beam focusing by a high-current plasma lens

Features of the electrostatic plasma lens (PL) in the regime of focusing of moderate energy (5-25 keV) high-current (up to 800 mA) wide aperture repetitively pulsed metal ion beam are investigated. It is shown that under these conditions use of the ohmic divider for fixing the external potentials on the PL electrodes is not effective because signification of electrons leakage. At the same time use of the RC- divider enables to sustain applied potentials permanent during the time of beam passing through. Some static characteristics in the PL volume are investigated. It is found that under condition of rigid fixation of potentials on the PL electrodes the electric field increase with a growth of passing ion beam current is restricted due to increase of the potential in the paraxial region of the beam. The estimations of limiting static electrical fields, which can be realized in the PL are made. These estimations are based on the model of quasi-neutral two-component PL with anomalous mobility of electrons. It is supposed that the anomalous mobility of electrons is caused by failure of electrons correlation when vortex-like structures appear in the hydrodynamic unstable plasma. The results of theoretical analysis are compared with experimental data.