Velocity space diffusion in Q-machine plasmas
Measurements of test particle diffusion in velocity space are reported. Test particles are created and examined using the method of optical tagging, an extension of laser-induced fluorescence. In quiet plasma conditions ( delta n/n>or=0.01%) results show diffusion to be linear with density in agreement with classical theory. Measurements taken in the presence of drift waves ( delta n/n approximately=6%) show resonant particle interactions. Applications to magnetospheric phenomena are discussed.