v0.11.0

New Features

• Adds functionality to optimize for omnigenity. This includes the OmnigenousField
  magnetic field class, the Omnigenity objective function, and an accompanying tutorial.
• Adds new objectives for free boundary equilibria: BoundaryError and
  VacuumBoundaryError, along with a new tutorial notebook demonstrating their usage.
• Objectives Volume, AspectRatio, Elongation now work for
  FourierRZToroidalSurface objects as well as Equilibrium.
• MagneticField objects now have a method save_mgrid for saving field data
  in the MAKEGRID format for use with other codes.
• SplineMagneticField.from_mgrid now defaults to using extcur from the mgrid file.
• When converting a near axis solution from QSC/QIC to a desc Equilibrium, the
  least squares fit is now weighted inversely with the distance from the axis to improve
  the accuracy for low aspect ratio.
• Adds a bounding box to the field_line_integrate defined by bounds_R and bounds_Z
  keyword arguments, which form a hollow cylindrical bounding box. If the field line
  trajectory exits these bounds, the RHS will be multiplied by an exponentially decaying
  function of the distance to the box to stop the trajectory and prevent tracing the field
  line out to infinity, which is both costly and unnecessary when making a Poincare plot,
  the principle purpose of the function.
• Adds a new class DommaschkPotentialField which allows creation of magnetic fields based
  off of the vacuum potentials detailed in Representations for Vacuum Potentials in Stellarators
  https://doi.org/10.1016/0010-4655(86)90109-8.

Speed Improvements

• CoilSet is now more efficient when stellarator or field period symmetry is used.
• Improves the efficiency of proximal optimizers by reducing the number of objective
  derivative evaluations. Optimization steps should now be 2-5x faster.
• Improved performance of Zernike polynomial evaluation.
• Adds a bounding box to the field_line_integrate defined by bounds_R and bounds_Z
  keyword arguments, which form a hollow cylindrical bounding box. If the field line
  trajectory exits these bounds, the RHS will be multiplied by an exponentially decaying
  function of the distance to the box to stop the trajectory and prevent tracing the
  field line out to infinity, which is both costly and unnecessary when making a Poincare
  plot, the principle purpose of the function.

Bug Fixes

• Fix bug causing NaN in ForceBalance objective when the grid contained nodes at
  the magnetic axis.
• When saving VMEC output, buco and bvco are now correctly saved on the half
  mesh. Previously they were saved on the full mesh.
• Fixed a bug where hdf5 files were not properly closed after reading.
• Fixed bugs relating to Curve objects not being optimizable.
• Fixed incorrect rotation matrix for FourierPlanarCurve.
• Fixed bug where plot_boundaries with a single phi value would return an
  empty plot.

Breaking Changes

• Renames the method for comparing equivalence between DESC objects from eq to equiv
  to avoid confusion with the common shorthand for Equilibrium.
• Minimum Python version is now 3.9

Github Commits