1. Budker Institute of Nuclear Physics, 11 Lavrentieva Prospect, Novosibirsk 630090, Russia
2. Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090, Russia
3. Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne, Switzerland