Theory, lab and space experiments, and calculations related the physics of [plasmas](https://en.wikipedia.org/wiki/Plasma_(physics)), i.e., matter constituted by [ionized atoms](https://en.wikipedia.org/wiki/Ion).
The critical conditions necessary for a medium containing charged particles to be considered a plasma are:
- the collection of particles in a given volume, typically a Debye sphere, exhibit a collective fluid-like behavior;
- the Debye length be much smaller than the system size (i.e., avoid boundary/edge effects); and
- the plasma frequency be much larger than the collision rate between electrons and neutral particles.
Wikipedia has a rather large list of topics related to plasmas at https://en.wikipedia.org/wiki/List_of_plasma_(physics)_articles.
When to Use this Tag
plasma-physics covers the physical description of plasmas (ionized media). It should be distinguished from quark-gluon-plasma. It can be combined with other tags such astrophysics to precise what type of plasmas are involved.