Current neutralization and plasma polarization for intense ion beams propagating through magnetized background plasmas in a two-dimensional slab approximation

A two-dimensional electromagnetic Particle-in-Cell (PIC) simulation model is proposed to study the propagation of intense ion beams with beam width w _b small compared to the electron skin depth c/ω _pe through background plasmas in the presence of external applied magnetic fields. The effective electron gyroradius w _ge is found to be an important parameter for ion beam transport in the presence of magnetic fields. In the beam regions, the background plasmas respond differently to the ion beam of width w _b < w _ge and w _b > w _ge for the given magnetic field and beam energy. For the case of beam width w _b < w _ge with relative weak external magnetic fields, the rotation effects of plasma electrons are found to be significant and contributes to the significant enhancement of the self-electric and self-magnetic fields. While for the case of beam width w _b > w _ge with relative strong external magnetic fields, the rotation effects of plasma electrons are strongly inhibited and a well neutralization of ion beam current can be found. Finally, the influences of different beam widths, beam energies and magnetic fields on the neutralization of ion beam current are summarized for the cases of w _b < w _ge < c/ω _pe, w _ge < w _b < c/ω _pe and w _b < c/ω _pe < w _ge.