An Anisothermal plasma is a plasma

Plasma (physics)

In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 which thermal state can be approximated by more than one temperature for the different degrees of freedom

Degrees of freedom (physics and chemistry)

A degree of freedom is an independent physical parameter, often called a dimension, in the formal description of the state of a physical system...

 of the plasma.
The degrees of freedom refer to translation (kinetic energy

Kinetic energy

The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

), rotation, vibration of each particle type.

Examples of anisothermal plasmas can be found among low-pressure plasmas that are excited by high frequency electric field

Electric field

In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

s, see frequency classification of plasmas

Frequency classification of plasmas

Electrical discharges applied in a plasma source for the generation of plasmas can be classified by the frequency of the exciting field. A rough classification is:*Direct current discharge *Pulsed DC discharge...

. They generally exhibit hot electron

Electron

The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

s that are powered by the alternating electric field, and a neutral and ion

Ion

An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

 component, which is significantly colder due the low efficiency of the energy transfer between light electrons and heavy neutrals and ions.

The term nonthermal plasma

Nonthermal plasma

A nonthermal plasma is in general any plasma which is not in thermodynamic equilibrium, either because the ion temperature is different from the electron temperature, or because the velocity distribution of one of the species does not follow a Maxwell-Boltzmann distribution.- Applications :In the...

 includes anisothermal plasmas and means that the different degrees of freedom of the plasma are not in thermal equilibrium

Thermal equilibrium

Thermal equilibrium is a theoretical physical concept, used especially in theoretical texts, that means that all temperatures of interest are unchanging in time and uniform in space...

.