Cross-field transport of test ions is investigated in a linear Q-machine plasma. Test particles are created and followed in their motion by an optical tagging diagnostic scheme. Diffusion is demonstrated to be supported by classical mechanisms. When different noble buffer gases are injected, the plasma reacts in such a way that the diffusivity remains classical but its magnitude is considerably reduced.

• Received 26 December 1991

DOI:https://doi.org/10.1103/PhysRevLett.68.2925