Turbulent Multiscale Interactions between Tearing Modes, Trapped-Electron Modes, and Zonal Flows

Area of Science:

• Plasma Physics
• Fusion Energy Research
• Computational Physics

Background:

• Magnetohydrodynamic (MHD)-scale tearing modes (TMs) and ion-gyroradius-scale trapped-electron modes (TEMs) are key players in fusion plasma dynamics.
• Understanding their interactions is crucial for achieving stable fusion conditions.

Purpose of the Study:

• To simulate and analyze the nonlinear interactions between MHD-scale TMs and ion-gyroradius-scale TEMs in a fusion plasma.
• To investigate the impact of these interactions on plasma transport and stability.

Main Methods:

• Global gyrokinetic simulations were employed.
• Fixed equilibrium profiles were used for consistency.

Main Results:

• Unstable core TMs nonlinearly coupled with and transferred energy to smaller-scale stable TMs near the plasma edge.
• Magnetic stochasticity induced by edge TMs eroded TEM-generated zonal flows.
• This erosion led to a significant increase in electrostatic flux.

Conclusions:

• The interaction between macroscale TMs and microscale TEMs suggests a pathway for controlling plasma microturbulence.
• Modifying the current profile presents a potential method for managing these interactions and improving plasma confinement.