What is a plasma ?

Plasma

A plasma is usually defined as a discharged gas which consists of positive ions and electrons.
It is well known that a matter has three stats. As the temperature of the matter gets higher, it changes its state from solid (liquid) to liquid (gas). What happens, if the temperature of the gas gets much higher ? Electrons bound in the molecules or atoms of the gas get enough energy to escape from the particle and the ions and electrons become dominant components of the matter (gas). And the ionized gas shows some features, which are not observed in usual states. Those features may be characterized by key words like Debye length, plasma oscillations, dispersion, instability, etc.
Thus, a plasma is sometimes called "the fourth state of a matter".

plasma diagram

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