Modernizing Interplanetary Particle Transport: Time-Dependent Diffusion, Turbulence, and Heliospheric Boundary Effects A Contemporary Extension of the Krimigis and Parker Diffusion Frameworks for the Dynamic Heliosphere

This study presents a comprehensive modernization of the classical interplanetary particle diffusion models originally developed by Parker and Krimigis. By integrating timedependent diffusion coefficients, turbulence-modulated scattering, particle drifts in the heliospheric magnetic field, and heliospheric boundary effects, the updated transport framework captures the dynamic and anisotropic nature of particle propagation in the solar wind. The model successfully reproduces key observational features, including the temporal and spatial profiles of solar energetic particle (SEP) events and cosmic ray modulation across the termination shock as measured by missions such as Parker Solar Probe and Voyager. These findings underscore the necessity of moving beyond steady-state diffusion approximations to accurately model energetic particle transport across the heliosphere. This work establishes a refined theoretical foundation that can inform future studies of space weather phenomena, cosmic ray physics, and heliospheric particle dynamics.