Gyacomo is a solver for the gyrokinetic Boltzmann equation in the delta-f flux-tube limit. It is based on a Hermite-Laguerre moment expansion of the velocity distribution function. The code supports kinetic and adiabatic electrons/ions, multiple geometries, advanced collision operators, and parallelization via MPI.
Originally developed at the Swiss Plasma Center, EPFL, Gyacomo is now open-source under the GNU General Public License v3.
Author: Antoine C.D. Hoffmann
Contact: ahoffmann@pppl.gov
gyacomo_cbc_Ti_torproj_movie.mp4
Movie of a cyclone base case (Dimits et al. 2000) simulation with Gyacomo, generated by the pygkyl library.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
It is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY—without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
If you use or mention Gyacomo in your work, please cite the following reference:
- Hoffmann, A.C.D., Frei, B.J. & Ricci, P. (2023). Gyrokinetic moment-based simulations of the Dimits shift. J. Plasma Phys. 89(6), 905890611.
doi:10.1017/S0022377823001320
Publications:
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Hoffmann, A.C.D., Frei, B.J. & Ricci, P. (2023). Gyrokinetic simulations of plasma turbulence in a Z-pinch using a moment-based approach and advanced collision operators. J. Plasma Phys. 89(2), 905890214.
doi:10.1017/S0022377823000284 -
Hoffmann, A.C.D., Frei, B.J. & Ricci, P. (2023). Gyrokinetic moment-based simulations of the Dimits shift. J. Plasma Phys. 89(6), 905890611.
doi:10.1017/S0022377823001320 -
Frei, B.J. (2023). A Gyrokinetic Moment Model of the Plasma Boundary in Fusion Devices. EPFL, Lausanne.
doi:10.5075/epfl-thesis-9960 -
Hoffmann, A.C.D., Frei, B., Giroud-Garampon, P., & Ricci, P. (2024). A gyrokinetic moment-based approach for multi-scale multi-fidelity turbulence simulations. Computational Challenges and Optimization in Kinetic Plasma Physics, Institute for Mathematical Science and Statistics Innovation, Chicago, IL.
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Hoffmann, A.C.D., Balestri, A., & Ricci, P. (2025). Investigation of triangularity effects on tokamak edge turbulence through multi-fidelity gyrokinetic simulations. Plasma Phys. Control. Fusion 67 015031.
doi:10.1088/1361-6587/ad9e6f -
Hoffmann, A.C.D. (2025). Nonlinear Simulation of Plasma Turbulence Using a Gyrokinetic Moment-Based Approach. EPFL, Lausanne, 2024.
doi:10.5075/epfl-thesis-10651
Gyacomo solves the gyrokinetic Boltzmann equation projected onto a Hermite-Laguerre velocity space basis. It supports flux-tube simulations in multiple geometries and includes kinetic effects, electromagnetic fluctuations, and advanced collisions using precomputed matrices from Cosolver (by B.J. Frei).
💡 This repository also includes personal post-processing MATLAB scripts. They're provided as-is and less documented — users are encouraged to write their own post-processing routines using the HDF5 output files.
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Run in parallel using MPI:
mpirun -np N ./path_to_exec Np Ny Nz
whereN = Np × Ny × Nz(parallelization in Hermite modes, binormal, and parallel directions). -
Run in single precision
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Handle kinetic or adiabatic electrons and ions
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Include perpendicular magnetic fluctuations
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Simulate in Z-pinch, s-alpha, circular, and Miller geometries
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Use various closures for linear and nonlinear terms
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Incorporate linear GK Landau, Sugama, and Lorentz collision operators
(requires precomputed matrices from Cosolver — ask for them!) -
Add background ExB shear flows (Hammett’s method)
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Use an adiabatic ion model (not fully verified)
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Include parallel magnetic field fluctuations (should be easy)
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Model finite ρ* (rhostar) effects (hard)
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Run without the futils library (easy, but tedious — ask for the zip!)
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Use shared memory parallelization (semi-working)
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Run global simulations (out of scope for now)
Detailed installation and usage instructions are available on the Gyacomo Wiki. You can analyze Gyacomo simulations either with matlab scripts stored here or with python Jupyter notebook with here.
🔧 Note: Some collision operators (Sugama, full Coulomb) require you to precompute matrix files using COSOlver and place them in the
Gyacomo/iCafolder before running simulations.
- Initial public release with GNU GPLv3
- Python post-processing utilities
- Installation tutorials
- Background ExB shear implemented
- Miller geometry benchmarked
- Support for SVD with LAPACK (for DLRA experiments)
- Perpendicular electromagnetic fluctuations (Ampère’s law, linearly benchmarked)
- Benchmarked for CBC against GENE (see
Dimits_fig3.m) - Sheared implementation via frequency transpose (kx → ky)
- Full 3D MPI parallelization (p, kx, z)
- Staggered grid for parallel odd/even coupling
- Adiabatic electron model
- Mirror force implementation
- 2D/3D hybrid mode (Nz=1 = 2D)
- Restart capability with different P, J
- GBS-style stop file procedure
- Parallelization in 2D (p, kr)
- Implementation of GK Dougherty and Cosolver-based collision operators
- New collisionality normalization (from νₑᵢ to νᵢᵢ)
- Versatile k_perp interpolation for Cosolver matrices
- Compatibility with MOLI MATLAB benchmarks
- First stable parallel release
- Nonlinear Poisson bracket term
- RK4 time solver
- Moment-hierarchy linear terms
- Fourier space linear Poisson equation
- Validation against Hasegawa-Wakatani system
- FFTW3 for convolution
- Support for Hermite and Hermite-Laguerre bases
- Start from GBS skeleton
Feel free to reach out for matrix files, help compiling, or contributing to the project!