1. Institute of Physics, CAS, Prague, Czech Republic
2. Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague, Czech Republic
3. Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic
4. Institute of Plasma Physics, CAS, Prague, Czech Republic
5. Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland
6. Service des Basses Températures, INAC-CEA, Grenoble, France