Confinement-Induced Transformation: Structural Dynamics and Layer Transition in Two-Dimensional Dusty Plasma*

In this work, the structural changes in a two-dimensional dust crystal using a novel method are demonstrated wherein the radial confinement of the dust system is adjusted while maintaining all other plasma discharge conditions constant. The experiments are performed in the DPEx-II device within a DC glow discharge Argon plasma setting [1]. Initially, the dust crystal displays a monolayer, hexagonal lattice within a confining circular ring at the interface of the plasma-cathode sheath. When the confinement strength around the ring is reduced, the crystal's hexagonal structure buckles, transitioning into a bilayer system with a square lattice pattern [2]. This reduction in confinement leads to the formation of various crystalline domains, showing ongoing structural adjustments. The duration of these rearrangements using the bond-orientational correlation function is measured, which shows that the dynamic and cooperative particle movements within the layers catalyze these changes over time [3]. 

References: 

[1] S. Arumugam, P. Bandyopadhyay, S. Singh, M. G. Hariprasad, D. Rathod, G. Arora, and A. Sen, Plasma Sources Sci. Technol. 30, 085003 (2021).

[2] Swarnima Singh, P. Bandyopadhyay, Krishan Kumar, and A. Sen. Phys. Rev. Lett., 129:115003 (2022).

[3] Chi Yang, Chong-Wai Io, and Lin I Phys. Rev. Lett. 109, 225003 (2012).

A.S. is thankful to the Indian National Science Academy (INSA) for the INSA Honorary Scientist position