# Investigations of Working Characteristics of Transferred Arc Plasma Torch Volume Reactor
## 1 Introduction  
The problem of waste generated by the development of industrial production and advanced modern technologies is becoming increasingly important. As the consumption of goods and services grows, increasing amounts of secondary raw materials such as various plastics, rubber, medical and chemical waste, etc. are generated [1; 2; 3]. Today's science faces new challenges, the solutions of which are related to the sustainable use of waste in the production of various products and equipment, as well as the neutralization and conversion of hazardous waste into environmentally friendly materials. Another important issue that researchers are paying increasing attention to includes energy resources [4; 5; 6; 7]. Fossil fuel resources are known to be finite and the use of fossil fuels poses problems such as environmental pollution and the promotion of the greenhouse effect. Therefore, there is an increasing focus on the use of secondary raw materials and waste alternative energy sources, for example, how to safely use waste heat for heating or electricity generation through the incineration, neutralization or other recycling of secondary raw materials [8; 9; 10]. There are many developed methods for neutralizing waste of various origins, such as incineration, pyrolysis and so on. However, most of these methods have a significant drawback as the process temperature reaches only 1500 \({}^{\circ}\)C, whereas, for hazardous wastes such as furans, chlorine or sulfur compounds and various carbon derivatives, these temperatures are not sufficient for neutralization or recycling processes. In order to neutralize or recycle particularly hazardous and hardly breaking waste, the process temperature must reach at least 1800 \({}^{\circ}\)C and above [8; 9; 10; 11; 12]. It is not possible to achieve such ambient temperatures using the traditional methods mentioned above. Alternatively, various types of plasma, such as RF plasma, arc discharge formed by plasma torch and other sources can be used to address this problem. Using various types of plasma, the process temperature can be around 5000 \({}^{\circ}\)C or even higher. Such temperatures are fully sufficient for the realization of all waste conversion and neutralization processes. However, in order for the waste neutralization process to be fully realized using a plasma environment, it is necessary that waste and other materials remain in the plasma environment for at least 1-2 s. To meet this condition, plasma-chemical reactors of various constructions are designed and developed and the waste particles inside them are retained for the required time and neutralized [13; 14]. In practice, volume plasma chemical reactors, non-transferred arc or transferred arc plasma-type reactors, etc., are commonly used. While using plasma neutralization technologies, the end result of waste neutralization is usually a gas. Using plasma technology, the main component of the system is the torch. Torches of various designs, such as AD/DC-type torches, short-term pulsed arc torches, microwave torches, laser-induced plasma torches and others, can be used to obtain thermal plasma [15; 16; 17]. The AC arc discharge ensures high energy density and a high temperature range between the two electrodes. At sufficiently high gas flows, the plasma extends in the form of a stream of ionized gas in a sufficiently large volume, which may be limited by the geometric dimensions of the reactor chamber. This design feature ensures that waste particles will remain in the reaction zone for the required time (1-2 s) and will be completely decompose into the gaseous form. Arc plasma generators are divided into nontransferred arc torch and transferred arc torch. Non-transferred arc torch electrodes do not participate in the processing of secondary raw materials and have the sole function of plasma generation. The material to be treated in the transferred arc reactor is placed in a metal grounded vessel that acts as an anode for the system [17; 18; 19].