DIFFUSE PLASMA DISCHARGE

What it is: Low-pressure, volumetric glow. 

The gas is conductive enough (or the pressure low enough) that the current spreads out evenly, filling the entire flask.

Visuals: Soft clouds, "Haze" or fog, uniform light, lack of defined edges.

Physics: Glow Discharge. 

The mean free path of electrons is long; they collide everywhere, exciting the gas in a volume rather than a line.

The Vibe: Ambient, Calming, "Atmospheric."