Particle trapping in a spherical symmetric magnetic field

The trapping of charged particles in a steady azimuthal magnetic field produced by a spherical uniformly distributed current was investigated. The equations of motion describing the dynamics of the charged particles in that field are solved numerically. An analytical study based on the guiding center, first order orbit theory, is developed. The results obtained from both approaches are presented and related to the available experimental observations. It is found that the azimuthal magnetic field configurations acts as a trapping system for both the electron and the ions. It is observed that the initial conditions assigned to the electrons play a determining role in the trapping and loss of the particles. On the other hand, the energy given to the electrons and the current generating the magnetic field greatly enhances or inhibits both processes. Some of the results of this study are directly applied to the plasma focus discharge. Several characteristic features of that phenomenon are explained by the model