3-Dimensional Dusty Plasma in a Strong Magnetic Field: Observation of Rotating Dust Tori

Abstract

The paper reports on the dynamics of a 3-dimensional dusty plasma in a strong magnetic field. An electrostatic potential well created by a conducting or non-conducting ring in the rf discharge confines the charged dust particles. In the absence of the magnetic field, dust grains exhibit a thermal motion about their equilibrium position. As the magnetic field crosses a threshold value (B $>$ 0.02 T), the edge particles start to rotate and form a vortex in the vertical plane. At the same time, the central region particles either exhibit thermal motion or $\vec{E}\times \vec{B}$ motion in the horizontal plane. At B $>$ 0.15 T, the central region dust grains start to rotate in the opposite direction resulting in a pair of counter-rotating vortices in the vertical plane. The characteristics of the vortex pair change with increasing the strength of the magnetic field (B $\sim$ 0.8 T). At B $>$ 0.8 T, dust grains exhibit very complex motion in the rotating torus. The angular frequency variation of rotating particles indicates a differential or sheared dust rotation in a vortex. The angular frequency increases with increasing the magnetic field from 0.05 T to 0.8 T. The ion drag force and dust charge gradient along with the E-field are considered as possible energy sources for driving the edge vortex flow and central region vortex motion, respectively. The directions of rotation also confirm the different energy sources responsible for the vortex motion.

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References in corpus (3)

• Experimental observation of self excited co--rotating multiple vortices in a dusty plasma with inhomogeneous plasma background
• Collective dynamics of large aspect ratio dusty plasma in an inhomogeneous plasma background: Formation of the co--rotating vortex series
• Comparative Study of the Surface Potential of Magnetic and Non-magnetic Spherical Objects in a Magnetized RF Discharge Plasma

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• A review on the Vortex and Coherent Structures in Dusty Plasma Medium
• Ring structural transitions in strongly coupled dusty plasmas
• Perspective: The dusty plasma experiments a learning tool for physics graduate students
• D-Mag: a laboratory for studying plasma physics and diagnostics in strong magnetic fields
• 3D tracking of particles in a dusty plasma by laser sheet tomography
• Comparative Study of the Surface Potential of Magnetic and Non-magnetic Spherical Objects in a Magnetized RF Discharge Plasma