Kinetic microtearing modes and reconnecting modes in strongly magnetised slab plasmas

Abstract

The problem of the linear microtearing mode in a slab magnetised plasma, and its connection to kinetic reconnecting modes, is addressed. Electrons are described using a novel hybrid fluid-kinetic model that captures electron heating, ions are gyrokinetic. Magnetic reconnection can occur as a result of either electron conductivity and inertia, depending on which one predominates. We eschew the use of an energy dependent collision frequency in the collisional operator model, unlike previous works. A model of the electron conductivity that matches the weakly collisional regime to the exact Landau result at zero collisionality and gives the correct electron isothermal response far from the reconnection region is presented. We identify in the breaking of the constant-$A_{\parallel }$ approximation the necessary condition for microtearing instability in the collisional regime. Connections with the theory of collisional non-isothermal (or semicollisional) and collisionless tearing-parity electron temperature gradient driven (ETG) modes are elucidated.

arXiv commentSubmitted for publication

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• A Drift-Kinetic Analytical Model for SOL Plasma Dynamics at Arbitrary Collisionality
• Influence of 3D plasmoid dynamics on the transition from collisional to kinetic reconnection
• Electromagnetic gyrokinetic instabilities in STEP
• Electromagnetic instabilities and plasma turbulence driven by electron-temperature gradient
• Theory of the Drift-Wave Instability at Arbitrary Collisionality
• Nonlinear microtearing modes in MAST and their stochastic layer formation
• Linear Theory of Electron-Plasma Waves at Arbitrary Collisionality
• Plasmoid instability in the semi-collisional regime
• Linear Collisionless Landau Damping in Hilbert Space
• The physics of a small-scale tearing mode in collisionless slab plasmas
• New linear stability parameter to describe low-$\beta$ electromagnetic microinstabilities driven by passing electrons in axisymmetric toroidal geometry
• A Hybrid Gyrokinetic Ion and Isothermal Electron Fluid Code for Astrophysical Plasma
• Multiscale Modelling for Tokamak Pedestals
• A Parallel-Kinetic-Perpendicular-Moment Model for Magnetized Plasmas
• Destabilization mechanism of the collisional microtearing mode in magnetized slab plasmas
• The gyrokinetic field invariant and electromagnetic temperature-gradient instabilities in `good-curvature' plasmas
• Symmetries of a reduced fluid-gyrokinetic system
• Microtearing Turbulence and Its Role in High-Density-Gradient Plasmas in Wendelstein 7-X