1. Dutch Institute for Fundamental Energy Research (DIFFER), De Zaale 20, 5612 AJ Eindhoven, The Netherlands
2. Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne, Switzerland
3. CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom
4. Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, NW17, Cambridge, Massachusetts 02139, USA
5. York Plasma Institute, University of York, Heslington, York YO10 5DQ, United Kingdom