Application of RF electric field to a charged-particle trap in toroidal geometry

In a toroidal magnetic configuration, charged particles have long orbit lengths Kondoh and Yoshida (Nucl. Instr. and Meth. in Phys. Res. A 382 (1996) 561), and hence, a slow method of modulating the kinetic energy can be applied to confine the particles in the trapping region. Numerical simulation shows that a spatially inhomogeneous radio-frequency electric field induces effective diffusion of the particles toward the trapping region.