1. The Department for Applied Physics, Perm National Research Polytechnic University, Perm 614990, Russian Federation
2. The Department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm 614990, Russian Federation
3. Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Shose, 1784 Sofia, Bulgaria
4. Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora, 1309 Sofia, Bulgaria