The transition from the magnetic focusing of the relativistic electron beam to the ion-focused regime

The REB dynamic in the region of the transition from magnetic focusing to the ion one has been examined, The azimuth-symmetric system has been considered. The field calculations have been performed under, long-wave approximation. For beam description the Vlasov equation has been treated by the particle method The emittance and the current of the beam after the transition region have been determined as a function of the ion channel radius; the channel density, the electron energy. the transfer region length. The transition from the focusing by the longitudinal magnetic field to the ion focused regime has been shown to be worthwhile when beam electron energies are so that the self beam field influence is negligible. The beam parameters after consistence period has weak dependence on the transition region length (if it is larger than two betatron lengths) and on the character of the magnetic field reduction. A t the consistence region the ion channel radius must be larger than the beam radius at least during the initial time intervals.