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Fixed-boundary QA vacuum
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This is an example calculation for a fixed-boundary QA vacuum equilibrium with 7
subvolumes. The relevant files are in ``examples/optimization/qa_vac_vol7``
with the input file ``init.toml`` which includes the profiles and initial
interface geometry which is obtained by interpolating the plasma boundary
inwards.

The flag ``lconstraint=3`` means that the invariant profiles are:

1. Pressure (in each subvolume)
2. Toroidal flux ``tflux`` (in each subvolume)
3. Integrated toroidal current ``ivolume`` (in each subvolume)
4. Integrated toroidal surface current ``isurf`` (on each interface)

This is a vacuum case so the currents and pressures are 0.

The calculation is run using the command ``calc_spectre_field.py init.toml``.
This can be done:

1. Locally: for instance using the script ``local_job.sh``
2. Using job scheduling: with slurm on a cluster as is done in the script
   ``slurm_job_jed.sh``. Note that the Slurm directives are cluster dependent.

During optimization, one can monitor the progress using scripts in
``scripts/minimization_monitoring`` which allow tracking iterations and
inspecting intermediate states.

After the equilibrium calculation, the following files are generated:

- ``init.h5``: output HDF5 file with the final interfaces, field, and various
  diagnostics
- ``init_opt.toml``: a restart TOML file that is equivalent to ``init.toml``,
  except it contains the optimized interface geometry which is now in force
  balance
- ``out.txt``: a text file with the output log, including the iteration
  information along with the initial and final error in the field and force

To analyze the result, one uses ``init_opt.h5`` which contains the equilibrium
field and allows for analysis and plotting using the class ``SPECTREout`` or
scripts in ``scripts/postprocess``. Alternatively, one can use ``init_opt.toml``
for further optimization, paramater changes, or additional Poincare tracing.

.. toctree::
   :maxdepth: 1

   analysis_qa_vac_vol7