(state of matter where atoms are not part of molecules and are ionized)
Plasma is a state of matter in addition
to solid, liquid, and gas. Plasma is gas-like
but the atoms are generally free of molecular bonds
and ionized. As a whole, a body of plasma is neutral,
but it includes positive and negative particles,
e.g., positive ions and electrons.
The "line" distinguishing plasma from gas
(i.e., "how much of the material needs to be ionized?")
has no universally-used precise definition,
but the general idea is that a gas is considered plasma
if it shows the distinct qualities of plasma,
which include electrical conductivity and
the generation of a magnetic field.
The plasma state is generally maintained by high temperature.
Much (perhaps most) of the matter in the universe is in
the plasma state.
Stars such as the Sun are sufficiently hot
as to ionize much of their matter
and the intergalactic medium through galaxy clusters is
generally highly ionized.
Plasma is used in technology such as neon
signs and plasma displays.
active galactic nucleus (AGN)
baryon acoustic oscillations (BAO)
coronal mass ejection (CME)
galaxy cluster (CL)
Herbig-Haro object (HH)
intracluster medium (ICM)
intergalactic medium (IGM)
interplanetary medium (IPM)
magnetic energy spectrum
partial ionization zone
radiative transfer (RT)
Reynolds number (Re)
Rosseland mean opacity
radiative transfer code (RT code)
equation of radiative transfer (RTE)
source function (S)
standard model of a flare
stellar model atmosphere
Sunyaev-Zel'dovich effect (SZ effect)