V.I. Ponomarenko - Dr.Sc. (Phys.-Math.), Professor, Department of Experimental Physics, V.I. Vernadsky Crimean Federal University (Simferopol), Institute of Physics and Technology. Е-mail: vponom@gmail.com V.V. Popov - Ph.D. (Phys.-Math.), Associate Professor, Department of Experimental Physics, V.I. Vernadsky Crimean Federal University (Simferopol), Institute of Physics and Technology. E-mail: slavapop@gmail.com I.M. Lagunov - Senior Lecturer, Department of Experimental Physics, V.I. Vernadsky Crimean Federal University (Simferopol), Institute of Physics and Technology. E-mail: lagunov.igor@gmail.com