About Plasma It's confirmed that there are 3 physical forms of material existence in human living environment. They are solids, liquids and gass. And any physical form can exist in different states due to the influence of environmental factors. Plasma is the fourth form of material existence. It's composed of ionized conductive gases, including six typical particles, which are electron, positive ion, negative ion, atom or molecule at excited state, atom or molecule at ground state, and photon. Plasma is composed of those positive and negative charged particles and neutral particles, and is a kind of quasi-neutrality gas with collective behavior. It's called plasma when the total negative electric charge equals to the total positive electric charge. 99% visible materials in universe may exist in plasma state, including fixed stars. Plasma can be natural or man-made. For example, the lighting during rainstorms is plasma phenomena, because the high voltage difference between cloud layer and ground makes the air ionized. And neon light and fluorescent lamp are from man-made plasma. The gases in light tube are ionized into plasma state.