High‐current plasma lens and focusing of intense ion beams

The static and dynamic characteristics of a high‐current plasma lens (PL) with the two‐component quasineutral plasma medium formed by a wide‐aperture pulse periodical ion beam and secondary ion–electron emission, with the features of focusing and control of a well‐formed low‐divergent multiaperture ion beam by this lens are investigated experimentally in a wide energy range. It is shown that a careful selection of magnetic field geometry, the fixing electrode number, and the external potential distribution on them, according to theoretical plasmaoptics principles, allow a radial electrical profile in a volume of PL to be modified in a given way. This enables the reduction of the spherical aberration of the beam which is being focused. Experimentally and theoretically it is shown that the controlled introduction of spherical aberrations makes it possible to control a radial beam profile on a target and, in particular, to make it homogeneous. The results of low‐energy metal ion beams focused and controlled by PL are obtained. Lens collective processes caused by a principally unremovable magnetic field radial gradient in the ion beam focusing direction are investigated and it is shown that lens electron leakages are connected with these turbulent noises.