Structural reset and non-equilibrium steady states in a dusty plasma under impulsive forcing

Abstract

This work investigates the response of a vortex-structured dusty plasma to a short, intense perturbation produced by a coaxial plasma jet operated at 1 kV. The jet delivers an impulsive forcing that accelerates dust grains far beyond their thermal velocities, leading to the complete loss of the coherent two-vortex organization. Despite this disruption, the cloud reassembles and a new non-equilibrium steady state (NESS) emerges. The macroscopic recovery extends over approximately 0.4–0.5 s, more than an order of magnitude longer than both the Epstein damping time and the local cage-reconstruction time, showing that the reorganization is governed by collective structural processes rather than single-particle dissipation. The post-perturbation state differs systematically from the initial one: the vortex core radii increase by 68%–83% and the circulation by 44%–56%, while the effective kinetic temperature of the flow-subtracted velocity fluctuations decreases by 27%. A global directional imbalance also emerges, with Ty/Tx increasing from 0.95 to 1.16. Four additional independent sequences spanning 250–450 mTorr show that destruction and collective reassembly of the vortex-organized cloud are reproducible, while the morphology of the reconstructed state varies between recordings. At 1 kV (250 J) the vortex organization is erased yet the cloud reassembles; at 2 kV (1000 J) the same source expels it irreversibly. The 1 kV event therefore defines a structural-reset regime in which strong impulsive forcing produces a quantitatively distinct NESS through collective reassembly rather than simple relaxation.