Investigation of 3D Energetic Particle Transport Inside Quiet-Time Magnetosphere using Particle Tracing in Global MHD Model

Abstract

Due to the presence of a magnetic field minimum in the outer cusp region, energetic particles drifting toward dayside may experience large scale transport toward high latitude. Some particle maybe trapped at high latitude and then be scattered back. These particle orbits are termed as Shabansky orbits [Shabansky, 1971]. Particle trajectories inside the magnetosphere can be grouped into three classes: bouncing around the equator (trapped), going through Shabansky orbit or being elevated at dayside, and lost. Characterizing these three types of particle trajectory and their dependence on solar wind conditions can help understand the trapping and loss of energetic particles in the radiation belt. We developed 3D test-particle tracing codes to investigate particle transport in global MHD model magnetosphere. In the code, protons are traced with full-motion and electrons are traced with guiding-center approximation. In this paper, we lay out the framework of studying the trapping and lost regions systematically and effects of the enhancement of the solar wind velocity on these regions. We derived the so-called Shabansky Orbit Accessibility Map (SOAM) for both electrons and protons to visualize the three orbital characteristic regions as a function of the particle's initial position and pitch angle inside quiet-time magnetosphere.