1. Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB, United Kingdom
2. Division of Fusion Plasma Physics, KTH Royal Institute of Technology, Stockholm SE-100 44, Sweden
3. Institute of Plasma Physics of the CAS, Za Slovankou 3, 182 00 Prague 8, Czech Republic
4. Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany
5. York Plasma Institute, Department of Physics, University of York, York YO10 5DD, United Kingdom