# Supply Systems of Non-Thermal Plasma Reactors. Construction Review with Examples of Applications
## 2 Non-Thermal Plasma Reactors  
Plasma reactors (PRs) are very unusual electrical devices. Their macroscopic characteristics are strongly non-linear and their work is generally carried out at high AC, DC or pulsed voltage, often with increased or high frequency. The discharge power, which is a measure of the efficiency of the plasma reactor, is regulated by the value of voltage or current, depending on the type of discharge, while the proper cooperation of the plasma reactor that in industrial applications is a high power device, with mains requiring additional devices such as reactive power compensation systems or filters, reducing distortion of the mains current.  
The reliable operation of the plasma reactor depends on the characteristics of the power supply system (PSS) and, on the other hand, the PSS responds to such an unusual receiver as the PR is. Therefore, the feed system must be designed and constructed together with the PR. In practice, various power sources are used to supply PRs, which can be divided into two main groups:  
* Transformer systems using the properties of magnetic circuits;
* Systems with power electronics elements.  
The above division is arbitrary, because both mentioned systems contain magnetic and power electronic elements. The latter, due to the enormous progress in the field of power electronics, are increasingly used to power plasma reactors. The use of the latest, fully controllable semiconductor components, such as GTO, MOSFET and IGBT transistors, allows the construction of power systems for plasma reactors with high power and high switching frequencies. Converter power supplies can provide the current-voltage characteristics and good current, voltage, power and frequency regulation required by the plasma reactor. They also enable automation of the plasma reactor operation by controlling the position of the electrodes, the composition and amount of the treated gas flow, and the plasma temperature.  
Recently, systems with impulse energy have been finding more and more applications in the processes of non-thermal plasma generation. Owing to the improvement of semiconductor and integrated circuit technologies, as well as the properties of magnetic materials, the use of pulse energy to power plasma reactors increases [46].  
To make a selection and design a PSS for a given plasma process, one needs to specify the requirements and parameters of the plasma receiver, the most important of which are:  
* Supply voltage--constant, sine, impulse;
* The presence of additional ignition system of the discharge or its absence;
* NTP reactor power and attainable power of the PSS;* The ability to adjust the current value and maintain its continuity in the entire area of the plasma reactor operation;
* Ability of the power source to work in automatic control and regulation systems and adjustment of parameters to various process gases and their mixtures;
* Correct cooperation with the power supply network;
* High efficiency;
* Simplicity and safety of use;
* Low capital and operating costs.  
These numerous requirements make the supply systems of non-thermal plasma reactors quite complex. In addition to the electricity supply system, they contain gas supply systems, gas velocity regulation and protection systems.