1. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
2. Department of Nuclear Engineering, University of California-Berkeley, Berkeley, California 94720, USA
3. Department of Physics, University of California-Berkeley, Berkeley, California 94720, USA
4. Keldysh Institute of Applied Mathematics RAS, Moscow 125047, Russia
5. Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, 182 21 Prague, Czech Republic