Cold atmospheric plasma
Plasma is a partially ionized gas and is called the fourth state of aggregation. In general, it is produced by heating matter to over 100,000 degrees. In nature, plasma can be found in the form of flashes or aurora borealis as a natural short-term electrical discharge. Plasma is a partially ionized gas. Electric arcs, the dielectric barrier, as well as corona and piezoelectric direct discharges ionize gases at atmospheric pressure creating “artificial” plasmas. The charged particles – electrons and ions – accelerate to very high energies. Only a small fraction of the gas molecules is turned into energetic electrons and ions; the rest of the gas remains neutral and cold.
In the case of cold atmospheric plasma, its temperature reaches only 50°C. When there is arc discharge, the arc volume reaches temperatures of 6.000 – 12.000°C. However, after leaving the discharge volume, the gas quickly cools down to 250-45°C. When processing speeds are set accordingly, these temperatures do not damage the surfaces treated. While the plasma remains cold, the very energetic electrons and ions collide with the gas molecules, producing large quantities of short-lived chemical species, such as atomic H, N and O species, OH and ON radicals, ozone, nitrous and nitric acids, as well as various other molecules in metastable excited states. They make this type of plasma chemically very active.
Upon contact with the treated surface, the chemically active cold atmospheric plasma initiates a multitude of physical and chemical processes. The main reaction agents are highly reactive short-lived neutral chemical species. Additionally, when the electric discharge touches the treated surface, the latter is also irradiated by VUV light and bombarded by the energetic electrons and ions. Although the quantities of the charged particles are small, their highly reactive nature strongly enhances the cleaning effect.
Advantages cold atmospheric plasma
- Very good for temperature sensitive materials and surfaces
- Can be used on the skin without any problems
- Generation at atmospheric pressure
- No waste as only electricity and ambient air are needed
- Chemically very active
