1. Colorado State University 1 , Fort Collins, Colorado 80523, USA
2. Lawrence Livermore National Laboratory 2 , Livermore, California 94550, USA
3. STFC Central Laser Facility, Rutherford Appleton Laboratory, Harwell Campus 3 , Didcot OX11 OQX, United Kingdom
4. XUV Lasers 4 , Fort Collins, Colorado 80523, USA