Fluorescent Tubes

[The Natural Philosopher]

The wikipedia also refers to unknown entities like 'viable renewable technology' in several places.

Its a useful resource, but not always written to the highest standards of honesty or accuracy.

[Andrew Gabriel]

An arc is a current flow in a plasma.

Plasma includes an arc, but it just means atoms have become disassociated so the charged particles are not locked together and are free to conduct electricity (in this case, electrons disassociated from their nucleus). Thus a plasma includes other situations such as high temp/pressure states where there's no arc (no current flow). Under some definitions, a solid metal is also a plasma (because the electons are mobile), but it's not normally useful to include this.

and it isn't - it's an electron beam in an otherwise vacuum.

Arc has jargon meaning in lighting, physics, and electronics, and they're all subtly different, and not well defined.

However, in the context of lighting, an arc is a current passing through a plasma, and includes fluorescent tubes, HID lamps, neons, carbon arc lamps, etc.