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

TL;DR

This paper introduces a drop tower setup that enables the study of dense granular media dynamics in microgravity using diffusing wave spectroscopy, revealing how sample volume and driving strength affect particle correlations.

Contribution

The novel setup allows independent control of volume fraction and driving strength, extending research capabilities for dense granular media in microgravity conditions.

Findings

Steady state achieved within fractions of a second in microgravity.

Correlation behavior depends on volume fraction and driving strength.

Distinct correlation decay patterns observed at different packing fractions.

Abstract

Investigation of dynamics in dense granular media is challenging. Here we present a setup that facilitates gas fluidization of dense granular media in microgravity. The dynamics is characterized using diffusing wave spectroscopy. We demonstrate that agitated granular media reach a steady state within fractions of a second in drop tower flights. The intensity autocorrelation functions obtained in microgravity show a remarkable dependence on sample volume fraction and driving strength. A plateau in correlation merges at low volume fractions and strong driving, while correlation decays only very slowly but continuously at high packing fractions. The setup allows to independently set sample volume fraction and driving strength, and thus extends the possibilities for investigations on dynamics in dense granular on ground.