Plasma is referred to a group of positive ions and electrons with an electric charge created by electrical discharge and plasma is known as the fourth state of matter besides other three states of materials (solid, liquid and gas). It was found by Crooks in 1879, first introduced to physics by American scientists, Irving Langmuir and Tonks, to describe the form of matter in the gas discharge tube.
When gas is applied with a greater energy, it becomes plasma with ionized elements. It is a good electrical conductor. Through ingenious magnetic field, plasma can be captured, moved and speed up. The physical development of plasma provides new technique and workmanship for material, energy, information, environment space, space physics, geophysics and other science. Plasma is a kind of matter form that mainly composes of free electrons and charged ions, and widely exists in the universe.
In an ordinary gas each atom contains an equal number of positive and negative charges; the positive charges in the nucleus are surrounded by an equal number of negatively charged electrons, and each atom is electrically "neutral". A gas becomes plasma when the addition of heat or other energy causes a significant number of atoms to release some or all of their electrons. The remaining parts of those atoms are left with a positive charge, and the detached negative electrons are free to move about. Those atoms and the resulting electrically charged gas are said to be "ionized". When enough atoms are ionized to significantly affect the electrical characteristics of the gas, it is plasma.
In addition to being important in many aspects of our daily lives, plasma are estimated to constitute more than 99 percent of the visible universe.
