High-current plasma lens: role of aberrations

Abstract

Influence of spherical and momentum aberrations of the electrostatic plasma lens (PL) on the focusing character of the intense ion beam on the target is analyzed. The beam form of a focused beam depending on the noncompensated space charge and finite azimuthal velocity at the PL exit is founded. The minimum focused beam radii are calculated for different system parameters. These radii are shown to depend on the beam particles charge to mass ratio. The radial profile of focused multicharged ion beams having unhomogeneous stepped form was founded out experimentally. This effect is most distinct near PL focus and grows when the PL magnetic field does. Tlus emerge a principle possibility to use the PL for ion charge state analysis.