Calculation of aberrations of a space charge lens and its possible applications

Electron space-charge lenses and spherical aberration correctors are studied theoretically. Many interesting features of space charge devices are revealed by considering some simple, but physically reasonable models. A `toroidal sub-beam' algorithm has been developed to model the evolution of the current and charge density distributions of charged particle beams taking into account space charge and initial thermal velocity effects. It is shown that a number of simple space charge distributions can compensate a large range positive spherical aberrations. Some practical structures of the space charge lenses are presented.