Effect of magnetic field on the phase transition in a dusty plasma

TL;DR

This study investigates how an external magnetic field influences the structure and stability of plasma crystals in a dusty plasma, revealing that increasing magnetic fields can cause rotation, shear, and eventual melting of the crystal structure.

Contribution

It provides experimental evidence on the magnetic field-induced breakdown of plasma crystals and analyzes the dynamics leading to melting.

Findings

Magnetic field causes rotation of plasma crystals.

Higher magnetic fields induce shear and melting.

Pair correlation function confirms crystal melting.

Abstract

The formation of self-consistent crystalline structure is a well-known phenomenon in complex plasmas. In most experiments the pressure and rf power are the main controlling parameters in determining the phase of the system. We have studied the effect of externally applied magnetic field on the configuration of plasma crystals, suspended in the sheath of a radio-frequency discharge using the Magnetized Dusty Plasma Experiment (MDPX) device. Experiments are performed at a fixed pressure and rf power where a crystalline structure is formed within a confining ring. The magnetic field is then increased from 0 to 1.28 T. We report on the breakdown of the crystalline structure with increasing magnetic field. The magnetic field affects the dynamics of the plasma particles and first leads to a rotation of the crystal. At higher magnetic field, there is a radial variation (shear) in the angular velocity of the moving particles which we believe leads to the melting of the crystal. This melting is confirmed by evaluating the variation of the pair correlation function as a function of magnetic field.