Mode-spectral analysis of 2D Coulomb clusters with fluctuating charges

The mode spectra of small $N = 3, 7, 12$ clusters of dust particles with fluctuating charges are analyzed. Particular attention is paid to the influence of correlated and uncorrelated charge fluctuations on the oscillation mode spectra of these clusters. It is found that the main signature of the correlated charge fluctuations is the shift of the lowest-frequency (shear) mode; other modes are split/shifted according to their mode number and the weight of the shear and compressional parts in their oscillation pattern. This is useful for diagnostics as the character of dust charge fluctuations extracted from the analysis of the cluster mode spectra provides important information on the plasma correlation length