Develop robust TGK-based construction of a constant PADC

Develop numerical techniques for the Taylor–Green–Kubo formalism that enable construction of a constant pitch-angle diffusion coefficient from pitch-angle rate-of-change correlation functions despite late-time noise accumulation in full-orbit simulations.

Background

Method M2a applies the Taylor–Green–Kubo integral of the correlation function of the pitch-angle rate of change. The authors show that the correlation functions become noisy at late times, and integrating them accumulates noise, preventing identification of a constant PADC from this method in their setup.

This indicates an unresolved methodological challenge: achieving stable TGK-based PADC estimates that are robust to noise.