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Change Log / Release Log for fbpic

0.10.1

This is a bug-fix release.

It deals with the fact that FBPIC happens to be incompatible with Numba version 0.42. FBPIC will now raise an error when Numba 0.42 is detected, and the user will be prompted to install Numba 0.41.

In addition, the code can now perform particle sub-sampling in the openPMD diagnostic.

0.10.0

This release introduces various improvements to FBPIC:

New features:

  • It is now possible to tune the amount of smoothing applied on the charge and currents produced by the macroparticles; see #268.
  • The documentation of the boosted-frame technique has been expanded. A new function allows to easily compute the number of PIC iterations that need to be performed in the boosted frame ; see #294.
  • The user can now set the name of the folder where the checkpoints are saved ; see #305.
  • The continuous injection of plasma (with moving window) is now more robust. This can in particular suppress noise that some users might have observed in the up-stream, continuously injected plasma, for very long simulations.

Bug-fixes:

  • There was a bug in the laser antenna when using multiple CPUs/GPUs. This bug has been fixed ; see #309.
  • The FlattenedGaussianLaser had bugs, esp. when initializing it out of focus. This is now fixed ; see #305 and #299.

0.9.5

This is bug-fix release. It corrects a bug that was happening exclusively for cubic shape deposition, when using the CPU (i.e. the bug does not occur on GPU) ; see #297 In addition, this release adds a safe-guard for the sign of the charge, for Gaussian beams #295, and for the sign of the Galilean velocity #293.

0.9.4

This release introduces various improvements to FBPIC:

  • The initial space-charge calculation produced unphysical fields for high-energy beams with space-charge. This is now fixed ; see #289

  • More flexible ionization API: The user can now store the electrons from different ionization levels into different species. In addition, the user can now set a maximum level of ionization ; see #288 and #283

  • Improved restart from checkpoints: for safer use, the restart now requires that the number of species is the same in the simulation (when calling restart_from_checkpoint) and in the checkpoint file. (New species can nonetheless be added after calling restart_from_checkpoint.) ; see #278

  • The plasma can now be initialized with a non-zero temperature (see the documentation of the method add_new_species) ; see #277

  • There is a new diagnostic (SpeciesChargeDensityDiagnostic), which allows to have the charge density of one given species ; see #287

Minor fixes:

  • More efficient CPU execution by treading the erase function ; see #276
  • When using FBPIC_DISABLE_THREADING=1, the code will not need to compile for each execution, thereby allowing faster turnaround ; see #279

0.9.3

This is a minor release.

It fixes a few bugs:

  • the restart mechanism for an arbitrary number of azimuthal modes ; see #275. Before this, restarting simulations worked only when using up to 2 azimuthal modes.
  • the diagnostics of rho for multi-GPU simulations ; see #265

In addition, this release introduces the possibility to inject a laser from a moving antenna ; see #262.

It also introduces a minor change in the LaserProfile API: the user should now pass the propagation direction (i.e. forward-propagating or backward propagating) to the laser profile directly ; see #260.

0.9.2

This is a bug-fix release. It fixes a bug in the initial space-charge calculation, that was introduced in version 0.9.1. (Previous versions do not have this bug ; see #254 for more details.)

In additional more laser profiles were added. This includes:

  • Donut-like Laguerre-Gauss laser profile #257
  • Flattened Gaussian laser profile #244

0.9.1

This is a minor release, which includes miscellaneous improvements to fbpic:

Bug fixes:

  • The restart mechanism now works with ionizable particles. (See #237)
  • For multi-CPU/GPU simulations using the Galilean scheme, the stencil extent and corresponding number of guard cells is now properly calculated. (See #240)

In addition, various improvements have been made to the documentation. (See #239 and #240.)

Finally, the charge/current deposition is now more efficient on CPU, when multiple species are used (See #234)

0.9.0

This version improves several features related to creation and continuous injection of particles.

New features:

  • New species can now be created with the new method add_new_species of the Simulation object. (See 228) This is particularly useful for simulations involving ionization. (See 231)
  • Macroparticles with zero weight will not be created anymore. This saves time and memory when running simulations where the plasma dens_func is 0 over long distances (223). In addition, a warning is now printed if the dens_func returns negative values (227).
  • Electron bunches can now be injected through a plane, in order to avoid space charge effects over long distances in the boosted frame (186).
  • MPI communications involve less synchronization (#217) and include support for GPUDirect (226). Note that this is for testing purposes for the moment. Multi-GPU/multi-CPU are still not officially supported.
  • The default number of guard cells and damp cells has been increased. (229)

Miscellaneous:

  • The style of warnings has been changed (227).
  • This new release includes the cross-deposition scheme (202). This is for testing purposes for the moment.
  • The arrays z and r of the interpolation grid are now calculated on the fly. (215)

Bug fixes:

  • The restart from checkpoint were slightly incorrect, due to an incorrect size of the grid, by one cell size (224). This is now fixed.
  • Continuous injection (with moving window) used to be incorrect for particles with different number of particles per cell in z. This is now fixed. (230)
  • Injection of a Gaussian bunch in the boosted frame did not involve checking that the particles are in the correct local subdomain. This is now fixed. (232)

0.8.0

This version allows FBPIC to run with an arbitrary number of azimuthal modes. (The previous versions only worked with 2 modes: m=0 and m=1.)

This version also includes various improvements:

New features:

  • Threading (on CPU) was only activated for numba 0.34 and numba 0.36. It is now also activated for versions above 0.36. (See #199)
  • The code can now run in parallel with the use_true_rho option (See #210)
  • When using verbose_level=2, multi-CPU simulations now print the node on which each MPI rank is running. (See #209)

Bug fixes:

  • The moving window used to only work in one direction. It can now work in both. (See #206)
  • In a multi-GPU run, the out-of-memory errors will stop the whole simulation, instead of having other GPUs waiting indefinitely for the one GPU that crashed. (See #212)
  • Version 0.7.1 introduced a minor bug in the GPU current deposition, which lead to slight differences between the CPU and GPU results. This has now been fixed. (See #216)
  • There was a minor bug in the restart code, which did not update the arrays of positions of the grid. This was only likely to affect restarts followed by the initialization of a laser (a rare case). This now fixed by calculating these arrays on the fly. (See #215)
  • The field and particle diagnostics will now automatically convert the input period to an integer, which avoids erratic behavior if a float was provided. (See #198)

0.7.1

This is bug-fix release. It fixes two bugs that were introduced in version 0.7.0:

  • The first bug only affected simulations performed on CPU (not on GPU), and typically lead to spuriously high charge density on the axis (see #191).
  • The second bug affected restarts from a simulation checkpoint, and typically lead to incorrect continuous injection of plasma and/or simulations crashing at restart time (see #192).

These two bugs are fixed in version 0.7.1.

0.7.0

This version incorporates various new features, optimizations and bug fixes. See below for a details.

New features:

  • The messages printed by FBPIC to the terminal have been improved. The Simulation class now supports a verbose_level argument, in order to choose the desired level of information #158.
  • More self-consistent initialization of the laser field #150. The laser initialization now supports arbitrary laser profiles and is always exactly divergence-free, even for MPI-decomposed simulations. More laser profiles will be implemented and documented in the next release.

New optimizations:

  • The code performs fewer Hankel transforms per iteration, and is thus faster #161.
  • Faster functions for removal/addition of particles on GPU #179

Bug fixes:

  • The position where plasma starts to be injected (for simulations with moving window, featuring no plasma initially in the box) has been corrected. This mainly affects boosted-frame simulations. #160
  • When restarting simulations from checkpoints, there was a bug in the particle weights, which is now fixed. #178
  • The current and charge density are now written in the fields diagnostics for iteration 0, whereas they were previously set to 0 in the diagnostics for this iteration. #178
  • The boosted-frame particle diagnostics used to fail in some cases on GPU due to an out-of-bound access, which is now fixed. #169

Changes related to the installation process:

  • FBPIC can now use numba 0.36 with threading #167 and #170.
  • FBPIC is now able to load MKL on Windows #177 and has better support when MKL fails to load #154.
  • FBPIC can now run without having MPI installed (for single-GPU or single-CPU node simulations) #143

0.6.2

This is a bug-fix release. It corrects an important bug that was introduced in version 0.6.1 for the Hankel transform on GPU.

0.6.1

This version allows FBPIC to run without mpi4py installed, in the case of single-proc simulations.

In addition, the current deposition on CPU, as well as the Hankel transform on CPU and GPU have been optimized and should have significantly faster execution time.

Finally, FBPIC now prints a message during just-in-time compilation.

0.6.0

This version allows FBPIC to use the MKL library for FFTs, on CPU. In most cases, this will result in faster code execution compared to the FFTW library, especially on CPUs with a large number of cores. FFTW can still be used with FBPIC if MKL is unavailable.

In addition, this version optimizes the number of thread per block on GPU for costly operations, which should also result faster code execution.

0.5.4

This is a bug-fix release. It fixes the initial space-charge calculation by ensuring that:

  • this calculation does not erase any pre-existing field (e.g. laser field)
  • this calculation gives correct results for multi-CPU/multi-GPU simulations as well

0.5.3

This is a bug-fix release. It ensures that threading is only used with the proper numba version (numba 0.34). It also fixes some issues with the MPI implementation (esp. in particle bunch initialization and charge conservation).

0.5.2

This is a bug-fix release, that solves an issue when using openPMD-viewer >= 0.6.0 to read the checkpoint files (for a restart simulation).

0.5.1

This is a bug-fix release, that solves an issue with the particle boosted-frame diagnostics, in the case where both the GPU and a moving window were used.

0.5.0

This version brings two majors changes to FBPIC:

  • The code now supports multi-threading on CPU (when using numba>=0.34), and is therefore much faster then it used to be on multi-core CPU architectures.

  • The code does not rely on the proprietary library accelerate anymore, and uses the open-source library pyculib instead. As a consequence, all the dependencies of FBPIC are now open-source.

In addition to these changes, several minor improvements have been made to the GPU code, including faster sorting routines (prefix_sum) and shorter compilation time (function signatures have been removed).

0.4.1

This is a bug-fix release, to solve an issue with the particle boosted-frame diagnostics, in the case where the GPU is used. The particle boosted-frame diagnostics now correctly run on the GPU.

0.4.0

This version incorporates ionization (ADK model). The implementation is Lorentz-invariant and thus works in the boosted-frame. The implementation is also fully compatible with GPU, MPI, openPMD diagnostics (including boosted openPMD diagnostics), and tracking (e.g. of the produced electrons)

In addition, several improvements were made to the code in general:

  • External bunches can now be loaded to the simulation from openPMD files, or from numpy arrays.
  • Particle tracking is now compatible with the boosted openPMD diagnostics.
  • The laser can now be injected in the simulation with a temporal chirp.

0.3.0

This version incorporates the 3rd order particle shapes, in addition to the pre-existing 1st order particle shapes. (2nd order particle shapes are not implemented.) In addition, particle tracking was implemented (i.e. particle can have unique IDs which are then output in the openPMD files.)

0.2.0

This version incorporates the Galilean scheme, in order to prevent the numerical Cherenkov instability for a plasma with uniform velocity. The user can now choose to run the simulation with either the standard PSATD, or with the Galilean PSATD scheme.

In addition, several improvements were made to the code:

  • The user can now choose to have each MPI rank run an independent simulation (e.g. for parameter scans). A corresponding example has been added docs/source/example_input.
  • The boosted-frame diagnostics can now be used in parallel simulations.
  • matplotlib was removed from the code's dependencies, and is not imported anymore, as it was sometimes slow to load.
  • The implementation of the particle periodic boundaries (for single-proc simulation) is more efficient. (The particle position is simply shifted.)
  • The option ptcl_feedback has been removed since it was seldom used.
  • The field push is now done with numba functions instead of numpy functions.