1. Centre for Advanced Instrumentation, Durham University, South Road, Durham DH1 3LE, United Kingdom
2. York Plasma Institute, University of York, York YO10 5DQ, United Kingdom
3. Dutch Institute for Fundamental Energy Research (DIFFER), De Zaale 20, 5612 AJ Eindhoven, The Netherlands
4. CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom
5. Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), 1015 Lausanne, Switzerland
6. Plasma Science and Fusion Center MIT, Cambridge, Massachusetts 02139, USA