Project Rat News

Stay up-to-date on the latest and greatest of Project Rat

The New Version of the Rat GUI, and thanks to NT-TAO for sponsering the time-dependent particle tracking!

April 15th, 2024

Since Rat GUI version 2.017.3 we have time-dependent particle tracking in the Rat GUI, and we are please to say that this feature was sponsered by nT-tao. Thank you very much nT-tao for sponsering this feature! Click on the video on the right to see results of the Particle Tracker in the Rat GUI with particles moving in both a magnetic and electric field. The electric field originates from the changing magnetic field; the self-fields of the particles are currently not included.

nT-tao logo.

Today we have released an update as well, which includes the improvement of the Adiabatic Quench Calculation. It is now optional to calculate the normal-zone-voltage based on a calculation of the normal-zone-propagation along a one-dimensional line, based on the selected material properties. This is especially useful for HTS materials.

If you are already using the Rat GUI you should have received an email about the update, if not, please let us know. We'll be releasing a tutorial video about the updated Adiabatic Quench Calculation soon.

The New Version of the Rat GUI: Important Notice!

February 17th, 2024

We continue our year with a major update as we release the new version of the Rat GUI today. In the latest version, there have been significant changes aimed at improving accuracy, especially in geometries involving non-rectangular cross-sections and Frenet-Serret frames. Therefore, it is important to note that you may see a slight change in the calculation results for geometries that use non-rectangular cross-sections or Frenet-Serret frames. If you have any questions regarding this update, please contact us via email.

The first change in Rat is the way line current elements are created. This has been refined to better handle non-rectangular cross-sections and Frenet-Serret frames, thereby enhancing overall accuracy. Also the way the Frenet-Serret frame calculates the velocity of the space curve has changed.

A Stellarator in the Rat GUI

This results in more stable results, especially on the transitions between different sections in geometries. The current density calculation inside Rat is also changed to deal better with non-rectangular cross-sections and Frenet-Serret frames. Additionally, when offsetting from a Frenet-Serret Path, using a Path Offset or Path Cable, the Darboux generators are re-calculated to ensure that the cross-section remains constant.

Next, modifications have been made to the integration of the force density over the coil in the Mesh Calculation post-processor. These changes aim to increase accuracy, particularly when dealing with non-rectangular cross-sections and Frenet-Serret frames. When using a Frenet-Serret frame on a Path that has straight sections in it it will only apply the Frenet-Serret equations to the curved parts and keep the existing straight sections unchanged. This allows to use Frenet-Serret in a wider variaty of cases, for example in a Cloverleaf Coil.

Another key improvement pertains to the calculation method for the local radius feature in CCTs. It no longer normalizes the magnet length and utilizes the radius at position zero when setting the amplitude of harmonics with an angle. This adjustment ensures more precise calculations.

In terms of practical functionality, adjustments have been made to the Cable Path in layer wound configurations to ensure the correct winding direction, with provisions for flipping direction in older models.

To complement these updates, a variety of new examples have been added to showcase the capabilities of the software, including Cosine-Theta coils, an LHC-dipole, a Stellerator, and Iter, among others. These examples are categorized for easy access in the Example Menu. Furthermore, extra examples for iron applications, such as Transformer and Actuator, have been included to demonstrate the versatility of the software in different contexts.

Lastly, various bugs causing crashes in the GUI under certain conditions have been addressed, along with improvements to the stability of FreeCAD export functionality, although further refinements to the FreeCAD export function are still in progress. The bug fixes include: a bug in crashing the GUI when making a new HTS Tape or HTS Core, a bug in the Distmesh crashing the Rat GUI when the element size function is zero somewhere, a bug causing the GUI to crash when the geometry generated is completely NaN or Inf. This should normally not happen, but we've added a catch just in case. We fixed a bug in the Custom CCT Path causing it to miscalculate the length of the magnet when using a certain number of sections per turn. This length is used when bending the magnet to a certain arc-length. The stability of FreeCAD export is improved, although it is still not perfect. A bug fixed in Edge Coils such that the orientation vectors are re-calculated (this is optional). This is useful when using imported Paths for the Edges from XYZ files. Finally, the Rat GUI now deals with the file separator being different on Windows when porting a model file from and to Linux or MacOs.

New in the Rat GUI: Introducing the Adiabatic Quench Calculation to the Rat GUI

December 12th, 2023

Our latest software update includes several enhancements and fixes. We've integrated an adiabatic quench calculation along with the necessary protection circuit, and a tutorial video will be added to the website soon.

But there is more. The track calculation post processor now features data and coil clipping, which has also been extended to both the Cartesian and Polar Grid Calculation post processors. There's a new capability to extract the clipping plane in the mesh calculation post processor. We've enhanced the polar grid calculation post processing by adding cylindrical coordinates, along with an option to write these coordinates and field to a file. For improved analysis, the mesh calculation output now includes relative reluctivity and permeability properties, which are especially useful in checking the saturation of an iron yoke. Particle emitters have been updated to allow setting kinetic energy in eV, providing an alternative to using total beam energy. We've also introduced new path group types: sub, array, dash, stair cable, and map, for which tutorials and manuals will be available soon.

Additionally, we've resolved an issue where GPU computation wasn't properly enabled when opening models saved on MacOS on a Windows computer with an NVIDIA GPU, and fixed a bug related to the iron solver when using tetrahedrons and reflecting or mirroring the iron mesh.

As always, please feel free to reach out to us when you have any comment or question!

Rat GUI is now available for macOS

October 29th, 2023

We are happy to announce a significant update to the Rat GUI, now available for download. This version introduces an improved iron solver with improved field calculation capabilities, as we have transitioned to analytically calculating surface integrals. This ensures a more accurate result of the magnetic field near the surface of objects composed of non-linear materials and permanent magnets. Alongside these advancements, we have also addressed important bug fixes to provide a smoother user experience.

For our macOS users, we’re excited to release a beta version of Rat GUI, compatible with both Apple Silicon and other configurations. The user manual has been updated to include a comprehensive installation guide for macOS, ensuring a hassle-free setup. We would like to bring to your attention a known issue in the macOS version, where the Rat GUI might respond differently after taking a screenshot using the "CMD+SHIFT+5" shortcut. This behavior can be reset by pressing "CMD+SHIFT" on the keyboard.

Finally, we have adopted SuperLU for the preconditioner of non-linear matrices.

The Non-Linear Solver is Now Available (and Open Source!)

August 20th, 2023

We're excited to share the newest version of the Rat GUI, now featuring a significant addition: the Non-Linear Solver. This enhancement facilitates the calculation of the magnetic field for non-linear materials, providing a broader range of applications for our users.

Open Source for the Community

Staying true to our philosophy of community collaboration, we've decided to make the Non-Linear Solver's source code open source. This decision reflects our belief in collective growth, transparency, and the power of shared knowledge.

Draft Manual Release

To assist users in understanding the Non-Linear Solver, we're introducing a draft of our manual. Notably, Chapter 6 (HB-Meshes) delves into objects with non-linear properties. In addtion, Chapter 8 (Distmesh Cross-Section) introduces methods to design almost any shape, which can be very usefull when modeling iron yokes for instance. As the manual evolves, we plan to release weekly updates. Keep an eye on our tutorials page for these updates and additional resources, or click on the image of the manual on the right.

Connect with Us on LinkedIn

We're extending our online presence! Join us on LinkedIn to stay informed about updates, interact with our team, and connect with other Rat users and supporters.

Updates to our EULA & Terms

As the Rat GUI grows, it's crucial that our documentation evolves with it. Our updated EULA and Terms now include new third-party licenses and underscore our commitment to user privacy. Any information shared with us for support purposes remains confidential, reflecting our dedication to trust and security.

Your feedback is essential, and we genuinely appreciate our user's continued support and insights. As always, you can always send us an email with any comment or question you may have.

Rat GUI Manual Figure

Rat GUI With Iron

Little Beast Engineering LinkedIn

Recent Rat GUI Improvements

March 22nd, 2023
Progress with Iron Solver

We've made some strides with our iron solver. Jeroen is now able to calculate the field inside iron based on the field from surrounding coils, thanks to this paper from Le-Van et al. This approach eliminates the need to mesh the air due to the utilization of an integral method. Preliminary tests confirm its reliability, showing consistent results for various meshes. These calculations, conducted in three dimensions, are efficiently completed within minutes. Our team is currently focused on incorporating this solver into the Rat GUI, aiming for its inclusion by September.

Rat GUI's Update Focus

Given the attention on the iron solver, this Rat GUI update primarily addresses bug fixes. Do check your inbox for our update email, and it might also be worth a peek in your spam folder just in case.

We hope these enhancements improve your experience with the Rat GUI and support your magnetic modeling endeavors.


Introducing Rat GUI Version 2.015.0

December 6th, 2022

We're pleased to present the latest release of Rat GUI, version 2.015.0. After taking some time for development, we've incorporated a range of new features. While we can't cover every detail here, a comprehensive list is available on our downloads page.

Highlights of the update

  • Enhanced Features: Our toolkit has expanded with more tools and functionalities. Details are available on our downloads page.
  • Valuable User Feedback: The evolution of Rat GUI is significantly influenced by our users' insights and comments. We appreciate your feedback and always welcome suggestions to improve.

We've sent an update e-mail to our Rat GUI community. If you haven't received it, please check your spam folder. If needed, you can contact us at If you're waiting for a response, occasionally checking your spam folder over the next three business days might be a good idea, as our e-mail occasionally ends up in there.

We hope you find the enhancements in Rat GUI version 2.015.0 valuable for your magnetic modeling tasks.

Updates to Rat GUI: Version 2.014.0

July 19, 2022

We're pleased to introduce Rat GUI version 2.014.0, bringing important updates to enhance user workflows and address known issues.

Key Updates
  • Error Detection Improvements: Invalid objects in the Model Browser will now be highlighted with an error message in a tool-tip that shows up when hovering over the invalid object in the Model Tree.
  • Upgraded Post-Processing: The Plane Calculation post-processing now allows for better visualization of coil cross-sections in the View Port. Additionally, users can represent the magnetic field with an improved vector plot, as shown in the image below.

We've informed our Rat GUI users about this update via email. If you didn't receive our email, please check your spam folder or reach out to us at We suggest checking your spam folder occasionally, especially if you're awaiting a reply within three business days.

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Rat GUI Update: Bug Fix for Version 2.013.3

June 22, 2022

We've addressed a glitch in the Frenet-Serret PathGroup found in Rat GUI version 2.013.3, enhancing its performance and reliability.

Key Fixes
  • Resolved the Frenet-Serret PathGroup bug.
  • Added a unit test to prevent similar issues in future releases.
For Our Users

If you use the Frenet-Serret equations, please update to the latest Rat GUI version for better results.

We've informed our Rat GUI users through email. If you haven't received it or need further assistance, contact us at Also, check your spam folder if you're waiting on a response, and we'll get back to you within 3 business days.

Rat GUI Update: Exciting Features for Coil Geometries

June 8, 2022

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Introducing Rat GUI's newest updates, focusing on advanced coil geometries for your projects.

Enhanced CCT Paths with Frenet-Serret Equations

Take advantage of the Frenet-Serret equations for dynamic custom CCT paths. This allows for precise no-hardway-bend coil geometries with HTS tapes, freeing you from traditional modeling constraints.

Improved FreeCAD Macro

Our updated FreeCAD macro ensures better handling of the Frenet-Serret frame and non-perpendicular tape edges. Plus, exporting non-rectangular conductors to FreeCAD is now simpler, using a loft connection method. More non-rectangular cross-section options are coming soon.

We appreciate your support and look forward to your feedback.

Refined CCT Wrapper Models: Your New Patch Is Here!

April 19, 2022

Post our recent Rat GUI update, we've optimized our software, especially around the CCT Wrapper Models.

Enhancements to CCT Wrapper Model
  • Unified Models: "CCT (skew)" and "CCT (ampl)" are now one, retaining backward compatibility.
  • Improved Definitions: CCT amplitude now operates independently of the number of poles.
  • Easy Model Transition: Older models saved with the latest Rat GUI automatically shift to the new format.
  • Flexible Geometry Settings: Define CCT geometry your way - by angle or amplitude.
  • Quick Model Access: Reach your last-used model straight from the Home Menu.

For clarity in the Canted Cosine Theta Model, we've added descriptive tooltips. We strive to better Rat GUI with every step, and your feedback fuels us.

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New Interface & Updated HTS Fits in Rat GUI

April 14, 2022
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Rat GUI's recent update introduces a white-themed design option, available in "Settings -> Themes". This change provides an alternative look for users who prefer a lighter interface.

In the material database, we've added the Fleiter-Bristow fit (refer to Appendix A.3 of this work). This is intended to provide an option that can be more precise in certain low field ranges. This new fit is supplemented with data from the Robinson Research Institute, Tohoku University, and Fujikura.

We've also made changes to the Custom CCT design process. Users now have the option to import paths from a CSV file. The addition of a barycentric rational interpolation algorithm aims to help in creating curves for pitch, radius, and harmonics.

Additional adjustments include more bending options for coils and CCTs and the introduction of the Plasma Ring Coil. We've also updated our calculation tools and data handling features to offer more versatility in designs.

If you didn't receive our update email and wish to stay informed about future changes, please contact us. For those new to Rat GUI, there's a thirty-day trial available here.

The First Update to Rat GUI

March 6, 2022
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We have released an update to the Rat GUI. For users who haven't received the update notice but want to be included in our mailing list, please get in touch. If you're unfamiliar with Rat GUI, a thirty-day trial is available. Learn more here.

Update Highlights

The recent update brings several new features and improvements:

The camera functionality now allows an orthographic view. This feature provides better control over the orientation axis of the viewport. We've also added an export function for Rat Models, enabling direct exports to Abacus mesh files. This is particularly helpful for those incorporating their magnet into platforms like Geant4 for particle physics simulations.

Custom CCT design has seen changes too. Users can now import paths from a CSV file. Additionally, the introduction of the barycentric rational interpolation algorithm aids in creating curves for Custom CCT attributes like pitch, radius, and harmonics.

The update also includes bug fixes, thanks to feedback from our users. If you come across any issues or have suggestions, please contact us at

For those still familiarizing themselves with Rat GUI, we're working on tutorials and a comprehensive user manual. In the meantime, any questions or assistance required can be directed to our email.

Introducing Rat GUI

February 14, 2022

We're pleased to announce the release of Rat Graphical User Interface (Rat GUI). The interface is designed to simplify interactions with Project Rat, making it accessible for both newcomers and experienced users alike.

What is Project Rat? It's a tool for magnet engineers, facilitating the modeling of magnets and calculating their electromagnetostatic properties. The integration of the Multi-Level Fast Multipole Method ensures a balance between accuracy and computational speed.

If you're interested in exploring Rat GUI, please contact us for a thirty-day trial version.

More information