Project Rat News

Rat GUI Version 2.024.1 Released

July 3rd, 2026

Today we are releasing Rat GUI version 2.024.1. This release contains many changes across visualization, post-processing, import and export, meshing, field calculations, and the nonlinear solver. It also includes a large internal overhaul of the field engine and solver libraries used by Rat GUI.

A new experimental volume rendering post-processor has been added for Cartesian and polar grid fields. It can be used as an alternative to the PostGrid isosurface view. The opacity editor has also been updated. It now uses draggable control points over a field histogram, similar to ParaView. This editor is available in PostGrid, PostMesh, PostVolume, and PostTracks.

The post-processing workflow has been improved in several places. Colorbars now have a small help and close overlay. PostTracks has an independent time bar. Post-processor windows now have icons, and they can be renamed from the right-click menu. Viewport output and exported images should also look sharper on high-DPI screens.

Import and export support has been expanded. Rat GUI can now export inductance matrices to VTU, length tables to CSV, and polar grids to mgrid files for Simsopt. A SIMSON importer for Simsopt coil JSON files has also been added. Many exports now run in background file I/O threads, so the user interface should remain responsive during file writing.

This release also adds important modeling and physics improvements. Force and torque calculations have been expanded across the modeling stack. Surface-force-density output for ParaView has been added. The nonlinear field reconstruction has been reworked, with magnetization stored at Gauss points and recovered to the nodes. Two reconstruction modes are available: FAITHFUL and SMOOTHED. The default mode is SMOOTHED.

The field engine and nonlinear solver have received major performance work. The MLFMM field engine has been restructured and GPU support has been expanded. The nonlinear solver has been optimized to reduce memory bandwidth limits on large models. These changes should make large field calculations and nonlinear solves faster and more scalable, especially when GPU computation is used.

Existing models may need a short review after updating. Nonlinear field and force results can change because the field reconstruction method has been improved. The node-merge tolerance has also changed. It is now relative to the local element size, and old absolute values are ignored. Please re-check this setting for older models.

Rat GUI version 2.024.1 is available for Windows, macOS, and Linux on the download page. If you have any questions or run into issues, please contact us at info@rat-gui.com.

New Rat GUI Update – Visualization, Stability & Workflow Improvements

April 7th, 2026

Today we are releasing a new version of the Rat GUI focused on improving visualization, stability, and overall workflow. Many changes are aimed at making the software more responsive and intuitive, while also improving accuracy under the hood.

A major visual improvement is the new transparency rendering using depth peeling. This replaces the previous multi-sampling approach and results in much more accurate and predictable transparency, especially for complex coil geometries. Additionally, coil transparency can now be adjusted directly via the color picker, giving you more control over how models are visualized.

We have also introduced a selection outline instead of coloring the full mesh, as shown on the left. This allows you to keep the original mesh coloring visible while editing, making it easier to interpret results at a glance. This option can be enabled from the View menu, under Glowing Selection Edges.

Working with multiple viewports is now clearer thanks to a new active viewport indicator in the top-right corner, refer to the figure on the right.

You can also enable axes visualization via View → Toggle Axes to better understand model dimensions. This same option is available for the viewport of the Mesh Calculation's post-processor.

Under View, one can now also enable dynamic background, which makes the background color changes when the model is rotate from the viewport. And the bloom or glowing effect inside the GUI can be enabled/disabled from the View menu now.

The Distmesh workflow has been significantly improved. Mesh generation is now more stable and uses gradient-based methods instead of finite differences. You can inspect cross-sections directly through the 2D plot viewer, and overall robustness has been improved.

In the mesh calculation post-processor viewport you can now hover with the mouse to directly read field values, making inspection much faster. Additionally, have added a spherical harmonics table in the post-processor of that calculation.

Adiabatic Quench Update

The adiabatic quench model has received major improvements, and the documentation has been significantly expanded. We highly recommend reviewing the updated manual section: Adiabatic Quench Documentation. A bug has been identified in the Adiabatic Quench Calculation, which has been fixed in this update. However, this might result in slightly different results for peak temperatures and detection times.

Performance & Responsiveness

The GUI is now more responsive during heavy operations. Mesh creation and file I/O are moved off the main CPU thread, meaning Rat keeps rendering frames while computations are running. This results in a smoother experience, especially for large models.

New Features

• Multipole cross-section design tool, access it by adding the Multiple Cross-Section to your Custom Coil
• Automatic Grading Calculation, add it to the Calculation Tree to access it
• Editor for Nb3Sn fit, access it by adding Nb3Sn as a material
• TikZ export for line calculations
• Optional colorbar in rendered images
• Version update notification via license server

FreeCAD & Geometry Improvements

FreeCAD export has been improved and now better supports geometries with holes (e.g. cooling channels or tubular conductors). The interface has also been simplified with more intuitive options.

Bug Fixes

This release includes several important bug fixes, including stability improvements in the Distmesh generator, fixes in the Curl pathgroup, restored bookmarks, and general robustness improvements across the application.

As always, we appreciate your feedback. If you have any questions or run into issues, feel free to contact us at info@rat-gui.com.

New Rat GUI Terms

February 19th, 2026

We have released an updated version of our General Terms and Conditions and our Individual Use Terms (together, the “Terms”). For more information on Rat GUI licenses, please consult our Licensing page.

The new Terms are dated 18 February 2026. As with all our terms, they will become effective thirty (30) days after publication. If you have any questions about the updated Terms, please contact us at info@rat-gui.com.

New Rat GUI update - License server overhaul and more!

October 10th, 2025

Today we released a new version of the Rat GUI with an improved license manager. Now you can easily see who on your team is using the license key—especially useful for larger teams with multiple licenses. There’s more: we’ve added a grace period for a missed heartbeat. A heartbeat occurs when the GUI pings the license server. The GUI will no longer be automatically deactivated if a heartbeat is missed, and users can now force a heartbeat from the license‑manager window.

We've also added new examples, like the Wendelstein 7-X stellarator, the Compact Muon Solenoid magnet system, and the magnets of the ATLAS Detector. Check them out in the GUI from "Home > Start from Example".

As always there are some bug fixes, and if you have any questions after downloading this new version, please feel free to contact us at info@rat-gui.com.

The Rat GUI is now part of Little Beast Software B.V.

February 5th, 2025

As part of a restructuring of Little Beast, we have divided our activities into two separate companies: Little Beast Engineering B.V. and Little Beast Software B.V.. We are pleased to announce that Rat is now part of Little Beast Software.

Nothing else changes — the Rat GUI will continue to be developed and supported by the same team, with the same owners, and under the same terms and conditions. You will receive the same service, updates, and support as you always have; only the company name handling the sales has changed.

As always, you can reach us with any questions at info@rat-gui.com.

Happy holidays! Rat GUI Update

December 18th, 2024

First of all, we would like to wish everyone happy holidays! May the coming year be as productive and rewarding as this one. As we wrap up 2024, we’ve prepared one final update for the Rat GUI, focused primarily on bug fixes. More details can be found on the download page. All users should have received an email with information about this update.

Additionally, you may notice that we’ve added a Linux AppImage to the download page. Please note that this is still in beta. If you have any feedback about using the AppImage on your Linux distribution, we would love to hear from you!

Fijne Feestdagen! (as we say in Dutch)

The new version of the Rat GUI

May 9th, 2024

This new version mainly has bug fixes and performance improvements. There is an important difference in the Particle Tracking Calculation; particle tracking now uses momentum instead of velocity. This is more stable when using high energy (>GeV) relativistic particles. Previously for high energy particles the default tolerances of the solver were too loose, and that resulted in some inaccuracies. The user was able to tighten the tolerances, and inprove the accuracy. Now that Rat uses momentum instead of velocity the accuracy is improved overall.

For many calculations the tolerances of different solvers are accesible to the user via the Node Editor. In general, one can tighten the tolerances bit by bit untill the results are not changing anymore, which indicates that the tolerance setting used are correct.

For more information on all improvements, see the changelog on the downloads page.

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.

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.

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.

MAJOR UPDATE:
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.

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 info@rat-gui.com. 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 info@rat-gui.com. We suggest checking your spam folder occasionally, especially if you're awaiting a reply within three business days.

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 info@rat-gui.com. 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

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.

New Interface & Updated HTS Fits in Rat GUI

April 14, 2022

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

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 info@rat-gui.com.

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.