Magward — Orbital Radiation Console

Live: https://bmazin.github.io/Magward/

Magward is an interactive calculator for the orbit averaged radiation flux on an Earth-orbiting spacecraft carrying a high temperature superconducting (HTS) coil for active magnetic shielding, inspired by the directional shielding concept of Hellmann, Olatunji, Parashar & Pollock, IEEE Trans. Appl. Supercond. 35(5), 3800305 (2025).

The left panel sets the orbit (altitude, inclination), spacecraft size, and magnet parameters (coil radius, ampere-turns, standoff distance, with a red warning when the coil field exceeds practical REBCO limits). The viewscreen shows an animated three.js Earth with the trapped radiation belts rendered volumetrically from the same model that drives the numbers — the inner proton belt in warm tones, the electron belts in cool tones, the South Atlantic Anomaly sweeping past as the Earth rotates — plus the spacecraft on its orbit track. Below, a log-log spectrum shows the orbit averaged differential flux per component — trapped electrons and protons, galactic cosmic rays, gammas, and secondary neutrons — with shielded (solid) versus unshielded (dashed) curves, and integral totals in the sidebar legend.

Run locally

Static site, no build step:

python3 -m http.server 8123
# open http://localhost:8123

Tests (physics anchors, ground-truth comparisons): node --test tests/*.test.js

Physics

• Trapped particles — NASA AE8MAX/MIN and AP8MAX/MIN omnidirectional integral fluxes as full 2D (E, L, B/B₀) tables generated directly from the model (tools/gen_aep8_2d.py, via radbelt). Geographic position maps to (L, B/B₀) through an effective eccentric dipole whose offset (700 km toward 19°N 148°E) is fitted so orbit averages match IGRF-based evaluation (tools/validate_orbit_avg.py: within 0.6–2.3× across ISS, polar, MEO, and GEO test orbits). Known residual: the SAA renders about 20° north of its true latitude — a tilted-dipole limitation.
• Magnetic shielding, applied by true rigidity R = pc/Ze, two components:
  1. Störmer forbidden zone — omnidirectional exclusion below R_St = 7.49 V·(m/A·m²)/((d+a)/m)², the whole-craft cutoff. This is the term that rewards large dipole moments (coil radius squared) and close coils, and it reproduces Earth's 14.8 GV equatorial cutoff as a limit.
  2. Directional wake — the defocusing-lens effect demonstrated in the paper (impulse approximation validated against their GEANT4 anchors), applied only over the arrival-direction sector the coil actually covers. Its cutoff scales with NI·d/a; coil radius cancels by Ampère's law. The magnet is assumed aligned with the local geomagnetic field; trapped particles arrive near 90° pitch angle, matching the paper's optimal geometry.
• Galactic cosmic rays — force field modulation (Vos & Potgieter 2015 LIS; φ = 550/1100 MV), sharp Störmer geomagnetic cutoff per orbit sample, Earth shadow. Protons plus He (A = 4) and a heavy group (A = 12) placed on the shared total kinetic energy axis with the 1/A Jacobian; modulated He/p ≈ 0.05.
• Gammas — cosmic X-ray background (Gruber et al. 1999) within its ≥3 keV validity range, plus an Earth albedo term. Unaffected by the magnet.
• Neutrons — an empirical ISS-scaled proxy anchored to BTN-Neutron measurements (~0.1 n/cm²/s baseline, ~50 in the SAA), driven by the shielded charged fluxes, with the atmospheric albedo term scaled by the Earth disk solid angle. Not a materials transport calculation.

This is an estimator, not a transport code. Trapped fluxes carry the AE8/AP8 factor ~2 class accuracy on top of the dipole-mapping residuals above; the wake model is an impulse approximation; the GCR cutoff has no east-west asymmetry or penumbra.

Repository layout

index.html  css/  js/           the app (vanilla ES modules + three.js via CDN)
js/physics/                     the engine: dipole, trapped, gcr, magnet,
                                gamma, neutron, orbit averaging
tests/                          node --test suite: model anchors, paper anchors,
                                IGRF ground-truth comparisons
tools/                          table generator + validation scripts (python,
                                needs radbelt)
reference/                      generated AE8/AP8 tables and provenance

Credits and license

Built with Claude Code. Earth textures from the three.js examples (NASA imagery). Trapped radiation models: NASA AE8/AP8 via nasa/radbelt. LCARS design language after Michael Okuda's TNG computer displays.

BSD 3-Clause License.