Ion Heating and Flow Driven by an Instability Found in Plasma Couette Flow

Area of Science:

• Plasma Physics
• Magnetohydrodynamics
• Astrophysical Plasmas

Background:

• Plasma Couette flow is crucial for understanding astrophysical phenomena.
• The Hall effect becomes significant in weakly magnetized, pressure-dominated plasmas.
• Previous studies have not fully explored instabilities in this specific plasma regime.

Purpose of the Study:

• To report the first observation of instability in weakly magnetized, pressure-dominated plasma Couette flow within the Hall regime.
• To investigate the coupling between Hall currents and low-frequency electromagnetic modes.
• To understand the mechanism of ion heating in this plasma.

Main Methods:

• Experimental observation of plasma Couette flow.
• Spectroscopic measurements to analyze ion heating.
• Development of linear theory to model the observed instability.

Main Results:

• First observation of instability in Hall regime plasma Couette flow.
• Identification of strong Hall currents coupling to a low-frequency electromagnetic mode.
• Spectroscopic evidence of a threefold increase in ion temperature due to resonant Landau damping.
• Linear theory predicts positive growth rates at finite beta and stabilizing effects at very large beta.

Conclusions:

• The observed instability is driven by high-pressure profiles in a Hall regime plasma.
• Resonant Landau damping is the mechanism responsible for ion heating.
• The derived linear theory accurately describes the instability and its dependence on plasma beta.