# Modification of Insulating Properties of Surfaces of Dielectric High-Voltage Devices Using Plasma
## 3 Current State of the Research and Solutions for the Surface Strength of Insulators
In investigating the mechanism of electrical breakdown in liquids, researchers have sought to measure the electrical strength value \(E_{\mathrm{p}}\) that is characteristic of the pure liquid itself; ideally, the goal is to find an \(E_{\mathrm{p}}\) value that is free from the influence of any external factors such as electrode composition, the condition of the electrode and dielectric vessel surfaces, and the measurement site configuration. In [31], very reproducible results are provided, allowing the correlation of the electrical strength \(E_{\mathrm{p}}\) with the molecular structure of two homologous series of liquid hydrocarbons. This line of research was followed by a more recent project from 2010 [32]; the concept addressed the measurement and evaluation of selected electrical characteristics of nanocomposite materials. The electrical breakdown voltage value \(U_{\mathrm{p}}\) and the surface resistance value \(R_{\mathrm{s}}\) in PE/SiO\({}_{2}\) nanocomposites were evaluated, and a comparison of the results [32] showed that the dispersion of small numbers of electrical nanocharges could improve the observed properties of the synthetic insulator. Another stream of research on the nanostructure of materials usable as dielectrics was addressed in [33]. Different contents and particle sizes of Cr\({}_{3}\)C\({}_{2}\) in composite materials were tested. The topic of nanocomposite structures was developed in [34]. The electrical strength \(E_{\mathrm{p}}\) of nanocomposites containing low-density polyethylene (LDPE) filled with TiO\({}_{2}\) nanoparticles was investigated and also evaluated. The surface modification of the TiO\({}_{2}\) nanoscale was shown to have a significant impact on the electrical strength during stress tests. The authors' research focuses on improving the surface electrical parameters of insulators through surface changes in the order of micrometers or at the atomic and molecular levels. Such modification is not expected to radically increase the breakdown strength with intensity \(E_{\mathrm{p}}\) through orders of magnitude; rather, the procedure aims to provide the possibility of an additional technological improvement in a device which has approached the limits of breakdown testing. The modification must have a long-term effect and must not be demanding in terms of technology or funding. Plasma discharge treatment at an atmospheric pressure nevertheless offers such an additional refinement of the insulator-dielectric surface. As shown above, these technologies are employed in other industrial domains; thus, the authors' research has centered on generating a suitable plasma discharge by a device usable in relevant branches of the industry [35; 36]. Current techniques [37; 38] deliver some plasma discharge parameters and evaluations that can be used as procedures and approaches to reduce the surface discharge in a device or apparatus. These options include, above all, the precise adjustment of the electromagnetic-electric field vectors [39; 40] and the parameters of the dimensions and nature of the materials, observing the manufacturing technology. Among the experimental projects published to date [21; 38; 41], a very promising direction lies in creating layered materials at the interface of dielectrics and forming nanomaterial composites with a subsequent increase in the surface strength \(E_{\mathrm{p}}\).