FASTRAD® Modules, discover all the functionalities:

Interface and Modeling

Create and handle 3D radiation models, import, export and modify entire STEP models

Graphical User Interface

Framework: menus, toolbar buttons, property dialog boxes, hierarchy tree
2D/3D viewer and easy object handling (rotation, translation, etc.)
Insertion of simple shapes (box, cylinder, cake, sphere, …)
Hollow out and merge operations on all shapes (including STEP) for creating complex shapes
Material definition interface with a database

CAD Toolkit

Advanced STEP import

Import models written in STEP format (AP209, AP214, AP214_is, partially AP203). Compatible STEP files can be generated by CAD tools.

Different options are available:

Import the full model or only a part of it
Upload the model progressively as it is imported (allows a heavy model to be imported on a computer with a limited RAM)
Information on the material can be retrieved from the AP214_is format.

Models can also be imported and exported in GDML format.

Component Database Interface

Extended Modelling

Sector analysis

Perform essential calculations by sector analysis (ray-tracing), calculate six face equivalent thickness, post-process results to optimize shielding

Sector analysis (ray-tracing)

Calculation by sector analysis can be performed on any FASTRAD® model containing simple and complex shapes.

Ray-tracing calculation tool capabilities include:

Single or multi-environments definition
Estimation of various quantities : TID, TNID, current, custom
Isolated detectors or 2D/3D mappings
Two calculation methods : slant path or minimum path
Multi-threading option
Optimized and/or detailed post-processing file

Six faces equivalent thickness

Sector analysis post-processing

The crossed thicknesses calculated by sector analysis can be displayed thanks to color-coded rays indicating the most critical locations in terms of radiation shielding (Figure 1).

Figure 1 – Display of the smallest crossed thicknesses

The rays can be projected on a box allowing the creation of spot shielding (Figure 2).

Figure 2 – Projection of crossed thicknesses on the unit to build a optimize shielding i.e. spot shielding.

2D/3D mappings calculated with Ray-tracing can be displayed on the model.

Figure 3: display of a 2D mapping on the surface of a PCB

Monte Carlo calculations & Scripting module

FASTRAD® gives you the keys to the most precise tool, the Monte Carlo particle transport calculation. Both Forward and Reverse methods are available. This tool provides dose, flux and charge deposition outputs

The Monte Carlo particle transport is based on the tracking of particle interactions with matter, based on the interaction cross sections. It considers material composition and particle behavior, allowing to get a higher level of accuracy. Calculation can be run on several threads (parallelization) to increase calculation speed.

The precision of the Forward Monte-Carlo tool can also be increased by adding the hadronic physics add-on. This allows for a better precision for the tracking of high energy protons and is compulsory for the tracking of heavy ions.

The scripting module allows to customize and optimize the use of FASTRAD® by interacting with the main FASTRAD® entities through scripts.

3D Forward Monte Carlo transport

This module allows to perform calculations using a Forward Monte Carlo algorithm. Primary electrons, protons and photons as well as secondary electrons, positrons and photons can be considered with the standard tool. When the hadronic physics add-on in installed, other particles (heavy ions, neutrons, …) are also tracked.

Several sources of particles can be defined at the same time. A wide range of source geometries can be defined, based on the model geometry or from virtual shapes.

Particle trajectories can be visualized and interaction properties are displayed when a track is selected (Figure 4).

The 3D mapping module allows calculation of deposited energies, transmitted integral flux and associated errors in sensitive zones previously specified. With this tool, critical zones can easily be identified (Figure 5).

3D Reverse Monte Carlo transport

TID and TNID can be estimated by using the Reverse Monte Carlo particle transport method for incident electrons and protons.

For complex 3D models, including different geometrical scales, the particle transport calculation becomes very time-consuming with the standard (Forward) Monte Carlo approach. The Reverse Monte Carlo approach gives a powerful solution for faster accurate calculations.

Primary and secondary electrons, primary protons and secondary photons (Bremsstrahlung) are considered.

The radiation environment is defined by several spectra of electrons and protons (no limit).

The particle transport simulation is performed according to the materials assigned to the point or volume targets. Note that the Reverse Monte Carlo method is dedicated to an isotropic environment.

As for the Forward method, the Reverse Monte Carlo method allows to display particle trajectories and interaction properties by double-clicking on one step of the particle path. The 3D mapping module allows to display deposited energies, charge deposition rate in dielectrics, transmitted flux and associated errors in sensitive volumes.

Depth curve

This tool allows for the calculation of depth curves, i.e. radiation-related quantities as a function of shielding thickness. The environment and a few calculation parameters (including a list of thicknesses and the shielding material) are the needed inputs and the calculation is then run with successive Monte-Carlo calculations, one per thickness.

Four quantities can be calculated: Total Ionizing Dose (TID), Displacement Damage Equivalent Fluence (DDEF), current density and fluence.

The depth curve calculation can be done for different geometry and detector types: solid sphere, shell sphere, point or volume detector.

As a result, a summary file is created that can then be used as the input for the sector analysis.

Scripting module

A script language has been integrated into FASTRAD®. It allows to interact with the main FASTRAD® entities. It also allows to perform parameterized tasks, to deal with custom file formats, etc.

A Script Integrated Development Interface allows to write a new script. A Script Portfolio is available in order to store script files and execute them quickly.

The possibilities offered by the script are limitless!

Internal Charging

By using FASTRAD®, the same geometry used for the dose analysis can be used for the internal charging analysis. The Reverse Monte Carlo method allows to consider the real geometry of the spacecraft while maintaining a reasonable calculation time.

The 3D internal charging analysis in FASTRAD® relies on two types of simulation: Monte Carlo particle transport, for current density and charge deposition calculation and Finite Element Analysis (FEA), for potential and electric field calculation. For the latter, the two methods need to be coupled.

Incident current density

The calculation of the incident current density, by using the Reverse Monte Carlo method, allows to rapidly identify an element potentially sensitive to electrostatic discharge, like coaxial cables, PCB or connectors, among several units.

Identification of the most critical components among several units in the spacecraft.

A surface mapping can be used to get the incident current density on a surface.

Incident current density on the PCB displayed by using a surface mapping.

Point detectors can also be used, to get the incident current density at a specific location. The current density is estimated for a field of view of 180° on the external face on which the point detector is placed. This is only available by using the Reverse Monte Carlo method.

Charge and dose deposition rates

The charge and dose deposition rates are needed to get the potential and electric field generated by internal charging. They can be provided from uniform values or from a mapping.

The Monte Carlo results can be scored in three different types of mesh: cartesian, cylindrical and tetrahedral.

An example of using the 3D mapping features on a specific element like a connector is displayed hereunder. The charge and dose deposition rates are scored in a tetrahedral mesh by using the Reverse Monte Carlo method.

(a) Electronic unit with connectors. (b) Zoom on the J03 connector. (c) and (d) Charge and dose deposition rates inside the connector obtained from a Reverse Monte Carlo particle transport.

Time-dependent charge and dose rates

A factor ranging from 0 to 1 can be applied to the magnitude of the charge and dose rates. This factor must be given with respect to the time of the electrostatic simulation. It can be used for charge and dose rates that come from a uniform spatial distribution or from a mapping. It allows the user to modulate the magnitude of the charge and dose rates to better represent realistic conditions in space.

Electric field

The 3D time-dependent electric field generated inside dielectrics or on floating conductors can be calculated and displayed in FASTRAD®.

The electrical potential and electric field are computed in 3D using the finite element method. This method requires a volume mesh that is created in FASTRAD®. The charge deposition rate calculated by a Reverse or Forward Monte Carlo particle transport is the source term for the calculation of the electric field. The potential and the electric field can be displayed in 3D to assess the risk of electrostatic discharge.

Example of the electric field distribution in a coaxial cable.

The first step, prior to obtain the potential and electric field, is to compute the charge deposition rate given in C/m³/s in 3D. The deposited energy is also computed in order to be used for the radiation induced conductivity.

The electric field is calculated by solving the potential in 3D. The numerical method can be iterative or direct. The simulation can be transient or steady-state. Boundary conditions for the potential must be assigned. When a conductor has no boundary conditions and is electrically isolated, it is considered as floating and can be charged.

Before running the FEA calculation, the method for the conductivity must be selected. Several methods are available.

The properties of the materials will be used depending on the selected conductivity model. Several features are available for setting the temperature and the conductivity of dielectrics.

FASTRAD® then calculates the potential and electric field and allows to post-process them in 3D. If a transient simulation is selected, the evolution of the electric field can be displayed at each time step. The maximum potential and electric field values are gathered in a result file. The maximum reached values can also be found directly in the 3D results by using the mapping features.

(a) and (b) Potential distribution at steady-state. (c) and (d) Electric field distribution at steady-state.

Conductivity

Constant and time-dependent temperature

In addition to the constant mode, a time-dependent temperature of the dielectric can be set. It will be used in the conductivity model that requires a temperature.

This new feature can be helpful if only the temperature of the dielectric is known, the conductivity will then be computed by FASTRAD®.

User-defined conductivity: time-dependent

A two-column file containing the time-dependent conductivity of a material can be used. This feature allows to consider for temperature variation in space during a mission.

User-defined conductivity: electric field-dependent

A two-column file containing the electric field-dependent conductivity of a material can be used. This feature allows to use existing measurements of conductivity as a function of applied electric field.

Export

The conductivity used in the electrostatic calculation can be exported and post-processed in 3D.

Capacitance

Radiation Protection

From low Earth orbit to space exploration missions, radiation stands out as a critical element to ensure the health and security of crews.

Radiation Protection for Crewed Missions

FASTRAD® is able to compute radiological quantities used to calculate radiation levels received by the body, tissue or specific organs. Hence, the equivalent dose, effective dose and many other radiation quantities defined by the International Commission on Radiological Protection (ICRP) and by the International Commission on Radiation Units and measurements (ICRU) can be estimated with FASTRAD® for any radiation environment in any geometric model.

The user can define different source types: single spectrum or a multi-ion source.

Transport of energetic particles – proton, electron, photon, neutron, positron, ions, alphas, deuton and triton – is performed with the Forward Monte Carlo method in FASTRAD®.

Figure 16 : Modeling of a human in a Martian habitat. In this cross section, the ground station is covered by a Martian regolith dome. FASTRAD® is able to simulate the transport of energetic particles coming from Galactic Cosmic Rays (GCR) and Solar Energetic Particles.

Figure 17 : FASTRAD® simulates the irradiation of the Martian habitat by solar energetic protons. The blue lines correspond to the trajectory of primary protons, the orange and yellow lines correspond to secondary neutrons and photons respectively.

Figure 18: Modeling of the International Space Station, low Earth orbit mission. FASTRAD® is able to model the transport of energetic particles (trapped particles, GCR, solar particles) through the shielding of the space station and estimate the dose received by the crew.

The goal of this functionality is to eventually optimize shielding to manage the risk of radiation on crews. The lifetime of a crewed mission can be designed to respect the ALARA approach (As Low As Reasonably Achievable). As an example, a Martian habitat has been mapped to estimate the effective equivalent dose received at different locations in the station.

Figure 21 : Mapping of the central module of the Martian habitat. Mappings allow to identify critical areas in terms of radiation related outputs (here the effective dose equivalent).

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FASTRAD® Modules, discover all the functionalities:

Interface and Modeling

Sector analysis

Monte Carlo calculations & Scripting module

Internal Charging

Radiation Protection

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