1. Laboratoire de Physique des Plasmas (CNRS, Ecole Polytechnique, Sorbonne Universités, UPMC Univ Paris 06, Univ Paris-Sud), Ecole Polytechnique, 91128 Palaiseau, France
2. Department of Physics and Technology, V.N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine