I'd love to start working on implementing the BRL theory into PlasmaPy as I don't see any implementations of it elsewhere. Unfortunately the full BRL theory from Laframboise's thesis is quite bulky so I'm not sure of the direct use of the raw theory. I think it should still be implemented but it might not be the most useful for quickly fitting curves. Chen has an algebraic curve that approximates BRL for probe potential less than plasma potential which is here: F. F. Chen, “Langmuir probe analysis for high density plasmas,” Physics of Plasmas, vol. 8, no. 6, pp. 3029–3041, Jun. 2001, doi: 10.1063/1.1368874. That could be more useful but isn't the true theory.

I'd like some input as to whether implementing the full BRL theory would be useful. If so, I can get started writing some code!

@rocco8773 — do you have any thoughts on this issue and @kuchtact's comment?

I say have at it. For now, put it into plasmapy.diagnostics. Depending on how expansive the code gets you (@kuchtact) can either create an appropriate file (e.g. brl.py) or a sub-directory (e.g. brl/). Once the functionality gets more hashed out, we can refactor the package/file structure appropriately.