Radiation Belt Invariants Library

Note

This package provides tools for radiation belt physicists to calculate the adiabiatic invariants K and L* from gridded models of Earth’s magnetic field. This package supports the T96 and TS05 empirical Tsyganenko magnetic field models, SWMF and LFM MHD simulation output, and data on an arbitrary structured grid.

[Paper] [Poster]

Table of Contents

• Release History
  • Full Changelog
• Methodology and References
  • What are the Adiabatic Invariants?
  • How are the Adiabatic Invariants Calculated?
  • References
• Citing
  • BibTex
  • MLA
• Reference/API
  • rbinvariantslib.invariants Module
  • rbinvariantslib.models Module

Installing

This module can be installed using pip and PyPI.

$ pip install rbinvariantslib

Brief Tour

Calculating L* from TS05

Below is code which calculates L* using the magnetic fields obtain from TS05 and placed on a regular grid, for a particle observated with a pitch angle of 60° observed at (-6.6, 0, 0) R _E (SM coordinate system).

from rbinvariantslib import models, invariants
from datetime import datetime
import numpy as np

# Get TS05 model input parameters from CDAWeb API
time = datetime(2015, 10, 2)
params = models.get_tsyganenko_params(time)

# Evaluate TS05 model on regular grid. This takes 10-15 sec.
axis = np.arange(-10, 10, 0.25)
x, y, z = np.meshgrid(axis, axis, axis)
model = models.get_tsyganenko(
    "TS05", params, time,
    x_re_sm_grid=x,
    y_re_sm_grid=y,
    z_re_sm_grid=z,
    inner_boundary=1
)

# Calculate L*. This takes 20-25 sec.
result = invariants.calculate_LStar(
    model,
    starting_point=(-6.6, 0, 0),
    starting_pitch_angle=60
)

print(f"L* = {result.LStar}")

Calculating K from SWMF

This code calculates the second adiabatic invariant K for a particle bouncing through (-6.6, 0, 0) R _E (SM coordinate system) and mirroring at at 50° magnetic latitude, using magnetic fields from SWMF simulation output in .out format.

from rbinvariantslib import models, invariants

model = models.get_model(
    "SWMF_OUT",
    "3d__var_1_e19971010-170000-000.out"
)

result = invariants.calculate_K(
    model,
    starting_point=(-6.6, 0, 0),
    mirror_latitude=50
)

print(f"K = {result.K}")