Thermodynamic potential in local turbulence simulations

Area of Science:

• Plasma Physics
• Computational Fluid Dynamics
• Thermodynamics

Background:

• Reduced local equations are common in tokamak turbulence computations.
• In these models, kinetic and magnetic energy are often neglected in the energy functional.
• This leads to a lack of constraints on velocity and field fluctuations.

Purpose of the Study:

• To identify conserved quantities beyond the standard energy functional in reduced plasma models.
• To derive new constraints on velocity and magnetic field fluctuations.
• To demonstrate the applicability of these constraints across different kinetic and fluid models.

Main Methods:

• Utilized the generalized grand canonical potential as a conserved quantity.
• Applied this potential to reduced local equations relevant to tokamak turbulence.
• Examined the conservation properties for Boltzmann, gyrokinetic, and fluid equations.

Main Results:

• The generalized grand canonical potential is conserved in reversible processes within these reduced models.
• This conserved potential provides constraints on velocity and field fluctuations that are not captured by the energy functional alone.
• The method is shown to be effective for Boltzmann, gyrokinetic, and fluid descriptions.

Conclusions:

• The generalized grand canonical potential offers a valuable tool for analyzing fluctuations in reduced plasma physics models.
• It provides a more complete set of conserved quantities, enhancing the accuracy of turbulence simulations.
• This approach is broadly applicable to various kinetic and fluid plasma models.