Study of Gas-Fluidization Dynamics with Laser-Polarized 129Xe
  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. 
R. Wang, M. S. Rosen, D. Candela, R. W. Mair, and R. L. Walsworth