Nonthermal Plasma Technology.

All substances change from solid to liquid, and from liquid to gas when energy or heat is added. This change is called phase change and occurs at constant temperature. When energy is added to the gas, electrons emerge from the neutral particles and become ions. The state in which many ions and electrons are intermingled is called "plasma" (Fig. 1) (1-4). The change from gas to plasma is based on an ionization reaction. The energy needed for the reaction is in the range of 1-50 eV, which is generally much more than latent heat energy in the phase change (0.01 eV). Therefore, the change from gas to plasma is not strictly classified into the phase change. However, plasma is often called the fourth state, whereas solid, liquid, and gas are the other states of substance. Plasma is generally defined as an ionization gas, which is electrically neutral macro-scopically (the local number density of ion ni is equal to the number density of electrons nnie). Both ion and electron particles in plasma are moved by the heat. In particular, the speed of electrons is much more than other particles because of their small mass and mobility. [ABSTRACT FROM AUTHOR]