Experimental validation of the analytic model for the temporal decay of the density auto-correlation function in a strongly coupled dusty plasma

Abstract

In a recent theoretical work [Dhaka et al. Sci. Rep. 12, 21883 (2022)], the method of determining the transport coefficients of a system from the time dynamics of the density auto-correlation function (DAF) was extended to complex plasma systems using the framework of a generalized hydrodynamics model. An exact analytical form of the density auto-correlation function of the thermal level spontaneous fluctuations of a Yukawa system was obtained. In the present work, we provide the first experimental validation of this analytical model for a strongly coupled dusty plasma system. The dusty plasma is produced by introducing micron-sized melamine formaldehyde particles in radio frequency argon discharges, and the DAF of the spontaneous dust density fluctuations is determined by optically tracking the trajectories of the dust particles. The experimentally obtained DAF is found to show a trend that is consistent with our earlier theoretical and numerical predictions. It is further used to determine the microscopic rate of heat diffusion for various values of the fluctuation wave-number k and obtain an extrapolated value of the macroscopic heat diffusion rate in the limit k →0. The experimental validation lends strong support to our generalized theoretical model, which can be usefully employed now in a variety of strongly coupled systems.