v0.14.0

What's Changed

• Updates default parameters for partition support size in the singular surface integrals.
• Enables tracking multiple field lines in Bounce2D.
• Adds desc.objectives.LinkingCurrentConsistency for ensuring that coils in a stage 2 or single stage optimization provide the required linking current for a given equilibrium.
• desc.objectives.Omnigenity is now vectorized and able to optimize multiple surfaces at the same time. Previously it was required to use a different objective for each surface.
• Adds a new objective desc.objectives.MirrorRatio for targeting a particular mirror ratio on each flux surface, for either an Equilibrium or OmnigenousField.
• Adds the output quantities wb and wp to VMECIO.save.
• Changes implementation of Dommaschk potentials to use recursive algorithm and symbolic integration, improving agreement of numerical results with the literature.
• eq.solve and eq.perturb now accept LinearConstraintProjection as objective. This option must be used without any constraints.
• Allows non-proximal optimizers to handle optimizing more than one Equilibrium object simultaneously.
• Renames compute quantity sqrt(g)_B to sqrt(g)_Boozer_DESC to more accurately reflect what the quantiy is (the jacobian from (rho,theta_B,zeta_B) to (rho,theta,zeta)), and adds a new function to compute sqrt(g)_Boozer which is the jacobian from (rho,theta_B,zeta_B) to (R,phi,Z).
• DESC/JAX version and device info is no longer printed by default, but can be accessed with the function desc.backend.print_backend_info().

New Features

• Adds Bounce integral methods with desc.integrals.Bounce2D.

• Adds Effective ripple desc.objectives.EffectiveRipple and Gamma_c desc.objectives.Gamma_c optimization objectives.

• Adds new compute quantities for partial derivatives in different coordinate systems.

• Adds a new profile class PowerProfile for raising profiles to a power.

• Adds an option scaled_termination (defaults to True) to all the desc optimizers to measure the norms for xtol and gtol in the scaled norm provided by x_scale (which defaults to using an adaptive scaling based on the Jacobian or Hessian). This should make things more robust when optimizing parameters with widely different magnitudes. The old behavior can be recovered by passing options={"scaled_termination": False}.

• Adds a new objective desc.objectives.CoilIntegratedCurvature for targeting convex coils.

• Adds the example "reactor_QA", which is similar to "precise_QA" but with self-consistent bootstrap current at finite beta.

• desc.objectives.CoilSetMinDistance and desc.objectives.PlasmaCoilSetMinDistance now include the option to use a softmin which can give smoother gradients.

• Adds a new function desc.coils.initialize_helical_coils for creating an initial guess for stage 2 helical coil optimization.

• Adds desc.vmec_utils.make_boozmn_output for writing boozmn.nc style output files
  for compatibility with other codes which expect such files from the Booz_Xform code.

• Adds a new objective desc.objectives.ExternalObjective for wrapping external codes with finite differences.

• Allows specification of Nyquist spectrum maximum modenumbers when using VMECIO.save to save a DESC .h5 file as a VMEC-format wout file

• Adds an option to VMECIO.save to specify the grid resolution in real space.

• Performance Improvements

• A number of minor improvements to basis function evaluation and spectral transforms to improve speed. These will also enable future improvements for larger gains.

• proximal- optimizers use a single LinearConstraintProjection and this makes the optimization faster for high resolution cases where taking the SVD (for null-space and inverse) of constraint matrix takes significant time.

• Chunking/batching can now be used in more places. Note that this might change the default behavior and you might get OOM (out of memory) errors.

  • Adds batching feature to parallelize singular integrals used in free boundary solves.
  • Adds chunk_size option to compute magnetic field methods to increase performance. Users may need to update their scripts to pass in bs_chunk_size=20 or some other reasonable number if out of memory occurs as the default attempts to perform the entire computation at once.
  • desc.objectives.CoilSetMinDistance and desc.objectives.PlasmaCoilSetMinDistance now have a dist_chunk_size option to break up the distance calculation into smaller pieces to save memory.
  • Changes hessian computation to use chunked jacfwd and jacrev, allowing jac_chunk_size to now reduce hessian memory usage as well.

Bug Fixes

• Small bug fix to use the correct normalization length a in the BallooningStability objective.
• Fixes I/O bug when saving/loading _Profile classes that do not have a _params attribute.
• Minor bugs described in #1323.
• Corrects basis vector computations made on surface objects #1175.
• Allows keyword arguments to be passed to GenericObjective and ObjectiveFromUser.
• Fixes bug where save_in_makegrid_format function did not correctly account for CoilSet objects with NFP>1 or sym=True attributes, and so would not save all the coils.
• Fixes issue with interpolator for singular integrals #1522 and additional checks 1519.
• Fixes the coil currents in desc.coils.initialize_modular_coils to now give the correct expected linking current.
• desc.objectives.PlasmaVesselDistance now correctly accounts for multiple field periods on both the equilibrium and the vessel surface. Previously it only considered distances within a single field period.
• Sets os.environ["JAX_PLATFORMS"] = "cpu" instead of os.environ["JAX_PLATFORM_NAME"] = "cpu" when doing set_device("cpu").
• Fixes bug in desc.input_reader.desc_output_to_input utility function for asymmetric equilibria profiles, where the full profile resolution was not being saved.
• Fixes bug when passing only sym into .change_resolution for FourierRZToroidalSurface, ZernikeRZToroidalSection and FourierRZCurve.
• Fixes bug that was setting ObjectiveFunction._things_per_objective_idx incorrectly. Now each _Objective can define a unique order that it expects to use parameters for multiple "things".
• Fixes bug that occurs when an NAE solution used with NAE constraints is asymmetric, but has a symmetric axis.
• Fixes bug in FourierCurrentPotentialField.change_Phi_resolution where N_Phi would be changed to M_Phi if N is not explicitly passed into the method.
• Fixes bug when setting current for a MixedCoilSet with an arbitrary tree structure.
• Corrects Cholesky factorized least-squares solve for wide matrices used in root finding.
• Fixes bug in the formula for computing "P_fusion".

Breaking Changes

• Adds support for Python 3.13 and removes support for 3.9 since new JAX versions require minimum Python 3.10.

Full Changelog: v0.13.0...v0.14.0