Description of issue / requirement to address

This is a general issue to gather requirements for a set of functionality relating to equilibrium queries. Once we have a fairly complete list of required functionality, we can then discuss implementation and do the work.

At present a wide range of different tools are available in the equilibria module and in the BLUEPRINT StreamFlow object. The latter has some functionality which is not present in the new module, but is set to be deprecated.

Proposed solution

In my head, there are three generic categories of request for information on an Equilibrium object:

• Calculation of some floating point value, integral or otherwise: (e.g. psi at some point, internal inductance of the plasma, flux surface elongation)
• Queries as to where some physical feature lies in space: (e.g. finding the O, X-points, finding the LCFS, finding a flux surface based on some criterion)
• Queries related to the structure of the core plasma: (e.g. profiles, values plotted on a per-flux-surface basis)
  Implement functionality for the following equilibrium queries:

At present, these bits of functionality are strewn about between equilibria/physics.py, equilibria/find.py, and equilbria/flux_surfaces.py. I propose to compile a list of desired functionality, restructure these tools in a clearer way, and implement any missing features.

Desired functionality

TO BE UPDATED as part of this issue

Alternative solutions

We could carry on as is and add in pieces of functionality piecemeal, but we're already struggling with organisation and duplication of little helper functions and the like.

Additional context

Quite a few people probably want to have a say in terms of what is required, so @hsaunders1904 @markj997 @DarioV86 @je-cook @alexanderianblair @DanShort12 , please feel free to comment on this issue.