# Supply Systems of Non-Thermal Plasma Reactors. Construction Review with Examples of Applications
## 1 Introduction  
Non-thermal plasma, commonly known as \"cold\", has been used for almost two hundred years. Its main source in the nineteenth century was arcing, and the first application, already at the beginning of the nineteenth century, arc lamps, which illuminated the streets of the world metropolises, such as Paris, London and New York [1; 2]. The industrial applications of plasma electrical discharge were initiated by the brothers [PERSON] and [PERSON], who built the first ozonizer (1857) and electric arc furnace (1878). At the beginning of the 20 th century, first in Nice (1907) and then in Sankt Petersburg (1908), plasma reactors with barrier discharges were introduced to drinking water treatment technology. The technology of using electric discharges to produce ozone is still used today, and so far there is no alternative [3]. The basis for the division of plasma applications for technological purposes is its interaction with gas molecules, which results in a change in the chemical properties, momentum and energy of plasma particles. The transformation of physical and chemical properties of plasma particles is the basis of chemical technologies such as surface modification, etching, thin film deposition, powder production, ozone generation, plasma gas and wastewater treatment, thermal waste treatment and others. The momentum and energy transformations of plasma particles are used practically to obtain plasma beams for biomedical engineering (plasma sterilization), laser technologies, rocket propulsion, for radiation generation and in plasma light sources [1; 2; 3; 4]. In industrial practice, metallurgy and plasma light sources are among the oldest but still successfully used plasma technologies. The last decades of the twentieth century have brought new applications for already used electrical discharges, which have always been the main source of plasma for technological purposes. These include such large areas of application as: microelectronics, technologies for producing semiconductors, superconductors, organic, bio- and nano-materials. The twenty-first century is the era of new materials and technologies for their production, which are currently based mostly on plasma and laser technologies. The latter are closely related to plasma, which is often a medium that strengthens the laser beam (pumping lasers), and are included directly in the plasma technology [1; 2; 3]. At present non-thermal (NT) plasma treatment is widely applied in environmental processes of air, water and soil decontamination and in biology and medicine. Environmental applications include:  
* Decomposition of nitrogen and sulfur oxides in flue gases and volatile organic compounds (VOCs) emitted during various industrial processes--many hazardous organic compounds are readily attacked by exciting species, free radicals, electrons, ions, and/or UV photons generated in low temperature plasma [5; 6; 7];
* Generation of hydrogen H and elemental sulfur S from hydrogen sulfide H\({}_{2}\)S;
* Conversion of the greenhouse gases (CO\({}_{2}\), C\({}_{2}\)H\({}_{4}\)) to synthesis gas or liquid fuels and their vaporization [8; 9; 10];
* Water purification by ozone treatment. The ozone synthesis typically takes place in electrical discharges in air or oxygen. They produce strongly oxidizing agents, such as OH*, H*, O*, O3, and hydrogen peroxide H\({}_{2}\)O\({}_{2}\). Moreover, the strong electric fields of electric discharges and UV radiation are also lethal to several kinds of microorganisms in water [5; 11];
* Removal of hazardous organic pollutants from waste water--pulsed corona discharges, dielectric barrier discharges (DBDs), and contact glow discharge electrolysis techniques are being studied also for the purpose of water cleaning;
* Soil treatment--the afterglow of discharges that generate a non-thermal plasma in air or in oxygen is the source of sterilization agents, like ozone, NO, activated oxygen and nitrogen, and is a reasonable alternative to conventional chemical methods [12; 13; 14; 15].