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Higher-order nonequilibrium term: Effective power density quantifying evolution towards or away from local
M Hasan Barbhuiya1, Paul A Cassak1, Subash Adhikari1
1Department of Physics and Astronomy and the Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA.
Physical Review. E
|February 17, 2024
Summary
Researchers developed a new metric, the higher-order nonequilibrium term (HORNET) effective power density, to quantify energy conversion in non-equilibrium plasma systems. This new metric is crucial for understanding complex plasma dynamics beyond local thermodynamic equilibrium.
Area of Science:
- Plasma Physics
- Non-equilibrium Thermodynamics
- Computational Astrophysics
Background:
- Assessing energy conversion in fluids and plasmas often relies on comparing power densities.
- Quantifying energy conversion in systems far from local thermodynamic equilibrium (LTE) is a significant challenge.
- Existing methods struggle to capture the full picture of energy dynamics in non-equilibrium plasma systems.
Purpose of the Study:
- Introduce a novel metric, the higher-order nonequilibrium term (HORNET) effective power density.
- Quantify the rate of change of departure from LTE in phase space density.
- Enable quantitative comparisons of non-equilibrium effects with standard power densities.
Main Methods:
- Developed the HORNET effective power density metric.
- Utilized particle-in-cell simulations to calculate HORNET.
- Analyzed spatial variations and temporal evolution of HORNET in simulated plasma processes.
Main Results:
- HORNET was calculated for magnetic reconnection and decaying kinetic turbulence in collisionless magnetized plasmas.
- HORNET was found to be a significant fraction of internal energy change power densities (8-35% for reconnection, up to 67% for turbulence).
- Demonstrated that the evolution towards or away from LTE is dynamically important in these plasma systems.
Conclusions:
- The HORNET effective power density is a valuable tool for analyzing energy conversion in non-equilibrium plasmas.
- The study highlights the dynamic importance of deviations from LTE in astrophysical and laboratory plasmas.
- HORNET has broad applications for understanding various plasma phenomena where non-equilibrium effects are prevalent.
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