During daily life, the most often contacted plasma is the sun, florescent lamp, neon light, and lightning, people’s common understanding of the plasma is a substance which emits light by itself.  Actually, plasma is composed of the electron, positive and negative charged ions, neutral gases, and free radicals, assuming substance of neutral electrical charge under normal circumstances, thus named “Plasma” by continental scientists, meaning the equal number of positively charged ions and negatively charged ions (mostly electrons) within a substance.  The definition of (Plasma) in Physics stated by physicians started in 1920s from the study of gas discharging electricity by Langmuir, which is the simplest method for Human workly created plasma.  The plasma state is the forth state of matter, after gaseous, liquid, and solid states, and represents the most abundant state for matter within the universe.

       The Plasma is a kind of partially ionized gas.   By applying voltage on 2 corresponding metal plates (Electrodes), the electron receives kinetic energy from the acceleration of the electric field, and during the movement process collides with other atoms and molecules thereby transferring energy across, due to the electron is a much smaller particle than the atom or molecule,  thus, the collision result does not increase the gases’ inertia, but enhances the PE (Potential energy), if the energy becomes large enough, would even cause the electron to escape the atom and produces a separate ion and electron.  Taking the response of Argon ionization as example, the equation can be shown as follows:

e- + Ar -> Ar+ + 2e-

      Through repeated electric field acceleration, the 2 electrons produced obtain enough energy to proceed with next round of dissociation, thus from 1 electron becomes 2, 2 become 4, and so increases geometrically, finally causing total dissociation collapse, and produces stable plasma, as displayed in diagram 1.

 

The common response to plasma dissociation in several ways as follows:
(1) Molecular dissociation
e- + A2 -> 2 A + e-
(2) Atomic ionization
e- + A -> A+ + 2e-
(3) Molecular dissociation
e- + A2 -> A2+ + 2e-
(4) Atomic excitation
e- + A -> A* + e-
(5) Molecular excitation
e- + A2 -> A2* + e-