Nonlinear dynamic processes in the electrostatic plasma lens and their influences on ion beam focusing

Summary form only given, as follows. The plasma lens (PL) is the axial symmetrical plasma-optical system, which transforms longitudinal electric field in to transversal one, the latter focuses and controls ion beams. The plasma lens is useful for fundamental investigations of properties of plasma-optical systems as well as for practical applications for ion beam focusing. Early the static and dynamic characteristics of a high-current plasma lens have been investigated experimentally. Now we consider high-current plasma lens hydrodynamic instability in nonlinear approximation theoretically. The specific characteristic of PL is the principally irremovable radial gradient of the magnetic field axial component in the ion beam focusing direction. It is shown that drift motion of electrons in variable electric fields, caused by it, is transformed into the set of single vortex structures. Computer simulations of appearance and dynamics such structures arc done. It is shown that evolutions of set of single vortex structures can led to creating of single stable large vortex in PL. This will affect characteristics of the focused ion beam and also the properties of focusing of wide-aperture low-divergence ion beams, for example it may evoke additional spherical and momentum aberrations. The role of spherical aberrations during the ion beam focusing, the methods of their removal and their using for changing radial profile of beam density have been determined. Estimations of maximum potential values, vortex velocity and size and also anomalous transition coefficients are done.