Quasi‐linear theory of anomalous resistivity

Abstract

Magnetic reconnection is a favored mechanism for understanding charged‐particle acceleration phenomena in space and laboratory plasmas. A change in magnetic field line topology is envisioned in magnetic reconnection to release the stored magnetic field energy. In order for this to take place, some form of dissipation to break the frozen‐in condition is required. Since the classical resistivity is often inadequate for collisionless plasmas, anomalous resistivity via charged particles interacting with fluctuating electromagnetic fields is customarily invoked. However, anomalous resistivity is often modeled rather than computed from theory. In this article, we formulate the theory of anomalous transport from first principles. It is found that the effect of fluctuations can be defined through three anomalous transport terms governing momentum and energy transport and the resistivity. To illustrate the utility of these derived equations, examples that bear relevance to the consideration of breakdown in the frozen‐in condition in magnetic reconnection are discussed.