Saturn Magnetopause Shadowing Test-particle Simulation Code
Year: 2026
Type: dataset
Abstract: This record provides the Python source code associated with the manuscript "Effects of Magnetopause Boundary Conditions on Energetic Particle Loss from Saturn's Magnetosphere" by Jiwoo Seo. The script calculates and displays the trajectory of one energetic electron or proton near a simplified, locally planar Saturn magnetopause. The model combines a Saturn-local-time-dependent magnetospheric magnetic field, a finite-width magnetopause layer, and a prescribed northward or southward magnetosheath magnetic field. The package contains one file, Saturn_MP_Shadowing_Test_Particle_Simulation.py. It requires NumPy and Matplotlib. All fitted field parameters are defined in the file; no external data files or project modules are required. Edit the settings in main() and run the file with Python. 1. main()Selects the particle species, kinetic energy, solar wind dynamic pressure, starting Saturn local time, magnetopause thickness, and magnetosheath field. It computes the initial relativistic speed and time step, launches the particle from the magnetospheric edge of the layer toward the magnetosheath, calls integrate(), and plots the sampled trajectory. The main panel shades the magnetopause layer; an inset shows the initial gyromotion. The default case is a 500 keV electron at 15 SLT with a 16,900 km layer and a southward magnetosheath field. 2. field_bz()Returns the local magnetic-field component B_z in tesla at an x–y position. On the magnetospheric side, it evaluates a pressure-dependent field profile using Saturn local time inferred from the local y position. It linearly interpolates across the magnetopause layer and uses a uniform field on the magnetosheath side. The fitted magnetospheric field magnitude is greatest at 12 SLT. 3. integrate()Integrates one relativistic trajectory using half-step position drifts and an exact-angle magnetic rotation of the momentum (a Boris-C-style update; Zenitani & Umeda, 2018). It obtains B_z from field_bz() at each step. It returns sampled x–y coordinates in Saturn radii for the main panel (xy) and a more densely sampled early-time inset (inset_xy). Integration stops at the specified y limit or maximum step count; no automatic escape classification is performed. 4. Constants and fitted parametersThe file defines the physical constants and particle rest energies used by the simulation. FIT contains the field-profile parameters beta and B0 for four solar wind dynamic pressures: 0.05, 0.10, 0.20, and 0.50 nPa. ALPHA controls the dawn–dusk asymmetry. The script selects one fitted parameter set per run; it does not refit the magnetic-field model. This is a configurable single-trajectory example of the manuscript's local test-particle model. It includes only a z-directed magnetic field: the physical magnetopause-normal component B_n is zero, and no electric field is included. It does not reproduce the manuscript's nonzero-'B_n' parameter survey, observational processing, or all figures. The code variable bn is a magnetic-field normalization scale, not the physical normal component B_n. ReferenceZenitani, S., & Umeda, T. (2018). On the Boris solver in particle-in-cell simulation. Physics of Plasmas, 25(11), 112110. https://doi.org/10.1063/1.5051077 FundingThis work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIT) (RS-2025-16069997).
Author: Seo, Jiwoo
Language: English
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225704366