Particle Source

The Excitation section of CHARGE allows you to add a particle flux source for internal or coupled charging simulations. This source is capable of being incorporated in the FEM solver of CHARGE allowing for the particle transport source code to simulate its interaction with matter. The types of particles used in CHARGE by this feature are electrons, protons, positrons, alpha and photon. The source can be defined to be active for the entire simulation or just a portion. Multiple particle sources can be added to allow the user freedom to create the total environment they desire and allow for multi-species interactions.

The source can be set up with one of several geometries and directions, which can be either Boxed, Cylindrical, Spherical, or Planar.

Instructions

In the Excitation section, click on the Particles button and then Add Particle Source to add a particle source to the Simulation tree under Sources. The source properties menu will come up with its available options in the HUD.
Expand the sections of the properties and edit the options to your liking. Follow links in the overlay to learn more about select properties.
When finished, click OK to complete the particle source definition.

General

Options

Entry	Meaning
Particle Type	The particle type for the source
Spectrum Type	Set the spectrum type for the particle source.

General

General Options Summary

General settings for the particle source tool.

General Options

Entry	Meaning
Number of Particles	The number of particles fired per time step.
Number of Time Steps	Total number of time steps.
Atomic Number	Atomic Number of an Ion.
Nucleon Number	Nucleon Number of an Ion.
Charge	Charge Value for an Ion.
Nuclear Excitation	Nuclear Excitation for an Ion.

Geometry Options

Entry	Meaning
Source Geometry	Set the shape of the geometry for the particle source.
+X	Add a source from the positive X-direction.
+Y	Add a source from the positive Y-direction.
+Z	Add a source from the positive Z-direction.
-X	Add a source from the negative X-direction.
-Y	Add a source from the negative Y-direction.
-Z	Add a source from the negative Z-direction.
Plane	Set the plane that will be used for the particle source.
Divisions	Set the number of divisions to be used for the particle source.
Plane	Set the plane that will be used for the particle source.
Direction	Set the direction of the plane in the positive or negative direction.
Incidence Type	Set the type of incidence for the spherical particle source.
Surface Deviation	Set the maximum deviation from the true surface position (in meters) when tessellating the surface source.
Angle Deviation	Set the maximum deviation from the true surface normal (in radian) when tessellating the surface. The normal vector determines the direction of the particle momenta.
Max. Aspect Ratio	Set the maximum permitted aspect ratio for the tessellation of the surface source.
Max. Edge Length	Set the maximum permitted edge length (in meters) for the tessellation of the surface source.
Reverse Source Direction	For the surface source, reverse the direction of the momentum vector for generated particles.
Charge Density	An analytical charge source applied to all FEM bodies in the simulation. The small charge of 1 e-15 C/(m3*s) is applied to initialize the FEM in a numerically stable state when the transport or the PIC isn't active. As a testing method, the analytic source is used to test the connectivity of the mesh by setting an artificial charge on a few FEM time steps, with some boundary conditions. This will create potential gradients that will allow the user to see in the results if all bodies are well connected.

Energy Spectrum

Energy Spectrum Options

Entry	Meaning
Path to input file	Path to input file.
Spectrum Energy Bins	-
Satellite Name	Name of satellite to be imported from STK.
Writes particle source spectrum from STK data	Button to sync particle source with STK file.
In Sync	Toggle to show if STK file has been synced.
Override File Currents	Set the current density that will be used for a single time step in place of the current density defined in the imported spectrum file.
Integral Flux Time	Time adjustment made to the manual entry of energy bins.
Spectrum Energy	Set the initial energy for particles generated from this source.
Current	Set the current density that will be used for a single time step in the spectrum file.
Current	Set a 'current density' that will be used for a single time step in the spectrum file, but rather than using Amps (Coulombs per second) per unit area, the current density is defined as number of particles (n) per second per unit area.