Drop tower setup for dynamic light scattering in dense gas-fluidized granular media

摘要

Investigation of dynamics in dense granular media is challenging. Here wepresent a setup that facilitates gas fluidization of dense granular media inmicrogravity. The dynamics is characterized using diffusing wave spectroscopy.We demonstrate that agitated granular media reach a steady state withinfractions of a second in drop tower flights. The intensity autocorrelationfunctions obtained in microgravity show a remarkable dependence on samplevolume fraction and driving strength. A plateau in correlation merges at lowvolume fractions and strong driving, while correlation decays only very slowlybut continuously at high packing fractions. The setup allows to independentlyset sample volume fraction and driving strength, and thus extends thepossibilities for investigations on dynamics in dense granular on ground.