Motion of ions in an electron cyclotron resonance plasma

The motion of ions emerging from an electron-cyclotron-resonance plasma source has been investigated. Trajectories have been calculated by solving the ion equations of motion in a divergent magnetic field and an electrostatic longitudinal accelerating field which has to be evaluated self-consistently. The trajectory calculations have been combined with a Monte Carlo procedure for choosing the initial ion phase space variables in order to study the propagation of the ion distribution function. It is shown that outside the chamber the spatial profile of this distribution is increasingly broadened with distance from the second magnet due to the diverging magnetic field lines, while at the same time the ions gain energy from the electrostatic field. For an argon plasma a mean ion beam energy of about 16 eV with respect to the plasma source potential results at the target plane in a distance of 60 cm from the source.