Test-Ion Diffusion in a Magnetized Plasma
Cross-field transport of barium test ions is studied in a Q-machine plasma. Test particles are produced and tracked in their motion by an optical tagging method. The comparison between the measured tag signal and a simple theoretical simulation yields a quantitative evaluation of the ion diffusivity. Diffusion is supported by classical mechanisms. The injection of different noble buffer gases modifies the plasma parameters in such a way that the diffusion remains classical but its magnitude is considerably reduced.