An Evaluation of Different Numerical Methods to Calculate the Pitch-angle Diffusion Coefficient from Full-orbit Simulations: disentangling a rope of sand
arXiv:2410.21001 · doi:10.3847/1538-4357/ad8b4a
Abstract
The pitch-angle diffusion coefficient quantifies the effect of pitch-angle scattering on charged particles propagating through turbulent magnetic fields and is a key ingredient in understanding the diffusion of these particles along the background magnetic field. Despite its significance, only a limited number of studies have calculated the pitch-angle diffusion coefficient from test particle simulations in synthetic magnetic turbulence, employing various, often quite different, techniques for this purpose. In this study, we undertake a comparative analysis of nine different methods for calculating the pitch-angle diffusion coefficient from full-orbit simulations. Our objective is to find the strengths and limitations of each method and to determine the most reliable approach. Although all nine methods should theoretically yield comparable results, certain methods may be ill-suited for numerical investigations, while others may not be applicable under conditions of strong turbulence. Through this investigation, we aim to provide recommendations for best practices when employing these methods in future numerical studies of pitch-angle scattering.
References in corpus (14)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- A comprehensive comparison of relativistic particle integrators
- Structure-preserving second-order integration of relativistic charged particle trajectories in electromagnetic fields
- Second order structure function in fully developed turbulence
- Novel aspects of cosmic ray diffusion in synthetic magnetic turbulence
- A generalized two-component model of solar wind turbulence and ab initio diffusion mean free paths and drift lengthscales of cosmic rays
- Pitch-angle scattering in magnetostatic turbulence. I. Test-particle simulations and the validity of analytical results
- Cosmic-ray pitch-angle scattering in imbalanced MHD turbulence simulations
- Determining pitch-angle diffusion coefficients from test particle simulations
- An fully implicit scheme for numerical integration of the relativistic particle equation of motion
- Pitch-Angle Diffusion and Bohm-type Approximations in Diffusive Shock Acceleration
- Pitch-angle scattering of energetic particles with adiabatic focusing
- Pitch-angle scattering in magnetostatic turbulence. II. Analytical considerations and pitch-angle isotropization