1. Center for Free Electron Laser Science (CFEL)Deutsches Elektronen‐SynchrotronHamburg 22607 Germany
2. Department of PhysicsUniversität HamburgHamburg 22761 Germany
3. Institute of PhysicsUniversity of PécsPécs 7624 Hungary
4. MTA‐PTE High‐Field Terahertz Research GroupPécs 7624 Hungary
5. Szentágothai Research CentreUniversity of PécsPécs 7624 Hungary
6. The Hamburg Centre for Ultrafast Imaging (CUI)Hamburg 22761 Germany