Magnetic field influence on laser-produced ion stream

Laser-produced plasma has been proposed to be an efficient source of ions which can be used for different applications (e.g., particle accelerators and ion implantation technology). In this article we present a study of the influence of an axial magnetic field on angular distributions of ions emitted from tungsten plasma produced using a 1 ns Nd:glass laser beam of energy 0.2-2 J at intensities of 1010-1011 W/cm2. Investigations were performed at magnetic field induction of 1.2 T. An electrostatic ion energy analyzer and a set of ion collectors located at different angles with respect to the target normal were applied for measurements of the ion stream characteristics. The results of measurements of angular distributions of ion emission show that the magnetic field causes a significant increase of a current density in ions close to the magnetic field axis (parallel to the target normal). The maximum current density of ions that expand in the magnetic field and considerably lower maximum current density of freely expanding ions increase fast with an increase of laser pulse energy. Simple Monte-Carlo simulations of laser-produced ions that expand freely and those expanding in the presence of an axial magnetic field are compared