Help: Drift shell

Table of Contents	ECSS	Model Page
Background Information	Miscellaneous models
	Drift shell

Energetic charged particles trapped in the Earth's radiation belts are confined to surfaces called drift shells. The drift shell tool provides a way to visualize these surfaces and their parameters in a variety of 2-D and 3-D plots.

The input parameters and options for the models are described below. When the input form has been completed, pressing the button will start the calculation and bring up the "Results" page.

Model parameters

The only parameter for the internal field model (DGRF/IGRF) is the magnetic field epoch. If an external field is selected, the day of year, universal time and other parameters (depending on the selected model) have to be entered. The date and time for the external fields are not related to the epoch of the internal magnetic field; they are used for coordinate transformations.

The drift shell can be defined in two ways in SPENVIS:

by a pair of magnetic coordinates: L and B_m, B_m/B₀ or the equatorial pitch angle;
by specifying a point on the drift shell defined by a set of geodetic coordinates and a local pitch angle.

Results

The drift shell tool produces the files listed in the table below. A description of the file formats can be brought up by clicking on their description in the table.

The report file spenvis_dsp.html contains the input parameters and summary tables. The summary file spenvis_dss.txt contains the foot points, mirror points and equatorial point for each field line of the drift shell in geocentric coordinates. The complete field lines are stored in the output file spenvis_dso.txt in the form of the geocentric coordinates of a (variable) number of points, the local magnetic field intensity and vector components, the distance from the magnetic equator along the field line, and the radius of curvature of the magnetic field line.

**Output files generated by the drift shell tool**
File name	Description
`spenvis_dsp.html`	Report file
`spenvis_dss.txt`	Coordinates of foot points, mirror points and equatorial points
`spenvis_dso.txt`	Coordinates of field lines making up the drift shell

To generate plots, select the plot type(s), options and graphics format, and click the button. The current page will be updated with the newly generated plot files.

Last update: Mon, 12 Mar 2018