What is the plasma in a plasma cleaner?

　　As people's requirements for quality of life are getting higher and higher, the plasma surface treatment technology and process of plasma cleaning machines are gradually being valued by various industries; and as the carrier of this emerging process, the research and discussion on the structure, principle and application of plasma cleaning machines are very worth looking forward to!

The plasma in the plasma cleaning machine is essentially the same as the plasma produced in nature. It is another state of material aggregation that is different from solids, liquids and gases. People call it the fourth state of material existence. It is composed of ionized conductive gases, including six typical particles, namely electrons, positive ions, negative ions, excited atoms or molecules, ground state atoms or molecules and photons.

When a substance changes from a lower energy aggregate state to a higher energy aggregate state, it needs to be supplied with energy from the outside (such as heating, electric field, radiation, etc.). When it changes from a solid to a liquid or from a liquid to a gas, each particle needs 0.01eV (1eV=1.6022×10-19 joule) of energy. When the gas further absorbs energy from the outside, the molecular thermal motion further intensifies, the molecules dissociate into atoms, and the electrons in the atoms gain enough energy to break away from the electrons and become free electrons. The gas is ionized, and the ionized gas contains a large number of electrons, ions, and some neutral particles (atoms and molecules). The charge numbers of electrons and ions are almost equal, and it is electrically neutral in a macroscopic or average sense. Take water as an example:

When the temperature is below 0℃, water will be solid, that is, "ice"; when the temperature is between 0℃ and 100℃, water will become liquid, that is, "water"; when the temperature rises to above 100℃, water will become gaseous, that is, "water vapor". After heating to tens of thousands of degrees, it will become the fourth state of matter - plasma!

Whether it is atmosphere (normal pressure) or vacuum (low pressure), process gases are introduced when modifying the surface of materials, such as clean compressed air without water or oil, nitrogen, oxygen, argon, etc. with certain purity requirements. What is the difference between these gases and plasma?

In order to convert the ordinary process gas introduced into the cleaning machine into plasma, each particle requires about: (1~30eV (1eV=1.6022×10-19 joule) of energy, and the particles have high activity and energy density.

But it should be noted that ionized gas is not necessarily plasma. Although plasma and ordinary gas have some common characteristics, such as they both satisfy the gas state equation, they have completely different properties. Nitrogen plasma is also red in the vacuum plasma state. Under the same discharge environment, nitrogen plasma will be brighter than argon plasma and hydrogen plasma.