1. AWE plc 1 , Reading RG7 4PR, United Kingdom
2. School of Mathematics, University of Bristol 2 , Bristol BS8 1UG, United Kingdom
3. Lawrence Livermore National Laboratory 3 , Livermore, California 94550, USA
4. Plasma Physics Group, Blackett Laboratory, Imperial College London 4 , London SW7 2AZ, United Kingdom
5. Los Alamos National Laboratory 5 , Los Alamos, New Mexico 87545, USA