  We report initial NMR studies of gas dynamics in a particle bed fluidized by
laser-polarized xenon (129Xe) gas. We have made preliminary measurements of two
important characteristics: gas exchange between the bubble and emulsion phases;
and the gas velocity distribution in the bed. We used T2* contrast to
differentiate the bubble and emulsion phases by choosing solid particles with
large magnetic susceptibility, in order. Experimental tests demonstrated that
this method was successful in eliminating 129Xe magnetization in the emulsion
phase, which enabled us to observe the time-dependence of the bubble
magnetization. By employing the pulsed field gradient method, we also measured
the gas velocity distribution within the bed. These results clearly show the
onset of bubbling and can be used to deduce information about gas and particle
motion in the fluidized bed.
