# Investigations of Working Characteristics of Transferred Arc Plasma Torch Volume Reactor
## 3 The Results of the Experiment
The formation of an arc in a thinner location of a nonconductive coating is associated with the formation of a negative surface charge, which prevents electrons from leaving towards the anode. On a thinner layer, this potential is lower; therefore, the conditions for an arc formation are more favorable here. The values of the electrical potential difference are also influenced by the changing distance between the plasma torch and the surface of the treated material, as part of the liquid phase material is removed and, in addition, the relief of the liquid surface is constantly changing [24]. The change in potential difference is also influenced by the fact that evaporation takes place during the melting of the processed material, which changes the composition and density of the gas inside the reactor. As the treated material evaporates, the electric arc becomes increasingly diffuse (more scattered than when there is no material to be treated in the reactor), which affects the dynamics of the potential difference. Looking at all these reasons for the change of electrical potential, it is difficult to quantify their impact. A scanning electron microscope was used to evaluate the external structure of the primary raw clay/hydroquinone material and the waste generated after the plasma chemical process in the plasma chemical reactor. The obtained SEM imaging results are shown in Figure 6. Figure 6a is a view of the primary feedstock before entering the reactor. As observed, the structure of the primary raw material consists of various irregularly shaped microformations. While analyzing this SEM image, it was observed that the geometric dimensions of irregularly shaped structures are very different and vary in the range of 1-10 \(\upmu\)m. Melting, boiling and evaporation of the feedstock take place inside the reactor during the plasma chemical process (these processes are the main ones that change the surface relief of the processed material). Therefore, it is natural that the amount of primary raw material is significantly reduced by melting or vaporization. Figure 6b shows an image of a material that is already processed during the plasma chemical process. The surface structure comprises various irregularly shaped microstructures. In this case, due to the effect of the process conditions, the microformations have smaller geometrical dimensions than the primary raw materials. The geometric dimensions of various microstructures vary approximately in the range of 0.5-5 \(\upmu\)m.  
In order to neutralize certain harmful substances (e.g., hydroquinone), it is necessary to use a secondary carrier so that the substance to be neutralized can be easily injected into the plasma chemical reactor. In this case, a dry clay powder mixed with hydroquinone was used as the carrier. The EDS method was used to estimate the chemical composition of this primary raw material. The results of the EDS studies are presented in Figure 7. As the results of the estimation show, the primary raw material comprises silicon 13.55%, calcium 6%, aluminum 5.7%, carbon 9.16%, iron 1.45%, potassium 1.77% and magnesium 1.34%. The analysis of the results shows that the material contains about 62% oxygen. Part of the free oxygen is concentrated in surface micropores. The rest of the oxygen is accumulated in the form of oxides, as part of the processed raw material does not comprise pure metals but  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Electric Arc Potential Difference**} \\ \hline
**Time, min. ** & **1** & **2** & **3** & **4** & **5** \\ \hline
6 & 2,9 & 3,12 & 3,2 & 2,4 & 2,2 \\
12 & 12,6 & 13,5 & 13,8 & 13,9 & 13,8 \\
17 & 30 & 30,6 & 30,1 & 27,7 & 28,5 \\
25 & 54 & 50 & 50,1 & 51,3 & 52,1 \\
35 & 63 & 69 & 68 & 63 & 4 comprise metal oxides instead. Some of the oxygen present at high temperatures can act as a catalytic gas, forming volatile compounds and accelerating the decomposition reactions of the material being treated.