Electron resonant interaction with whistler-mode waves around the Earth's bow shock II: the mapping technique

TL;DR

This paper introduces a new mapping technique to model electron distribution changes due to nonlinear resonant interactions with intense whistler-mode waves near Earth's bow shock, extending previous probabilistic methods.

Contribution

It develops a generalized mapping approach that captures non-diffusive electron scattering by long wave-packets, improving modeling of wave-particle interactions.

Findings

The technique accurately predicts electron distribution evolution.

Comparison with numerical integration validates the method.

Handles nonlinear resonant effects beyond quasi-linear theory.

Abstract

Electron resonant scattering by high-frequency electromagnetic whistler-mode waves has been proposed as a mechanism for solar wind electron scattering and pre-acceleration to energies that enable them to participate in shock drift acceleration around the Earth's bow shock. However, observed whistler-mode waves are often sufficiently intense to resonate with electrons nonlinearly, which prohibits the application of quasi-linear diffusion theory. This is the second of two accompanying papers devoted to developing a new theoretical approach for quantifying the electron distribution evolution subject to multiple resonant interactions with intense whistler-mode wave-packets. In the first paper, we described a probabilistic approach, applicable to systems with short wave-packets. For such systems, nonlinear resonant effects can be treated by diffusion theory, but with diffusion rates different from those of quasi-linear diffusion. In this paper we generalize this approach by merging it with a mapping technique. This technique can be used to model the electron distribution evolution in the presence of significantly non-diffusive resonant scattering by intense long wave-packets. We verify our technique by comparing its predictions with results from a numerical integration approach.