1. Department of Industrial Engineering, University of Rome “Tor Vergata”, Via del Politecnico 1, Roma 00133, Italy
2. National Institute for Laser, Plasma and Radiation Physics, Magurele-Bucharest RO-077125, Romania
3. Consorzio RFX (CNR, ENEA, INFN, Universita’ di Padova, Acciaierie Venete SpA), Corso Stati, Padova 35127, Italy
4. Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Lisbon 1049-001, Portugal