Numerical and experimental study on mitigation of electromagnetic pulses at the XG-III laser facility

Laser-target interaction generates intense electromagnetic pulses (EMPs), which severely interfere with physical diagnostics and even damage equipment. Since EMP generation is mainly attributed to electron emission and return current along the target holder, numerical simulations and experimental verification are combined to reveal the contributions of these two sources. The results indicate that a conductive target holder radiates EMPs with a higher magnitude of 189.5 kV/m than 88.9 kV/m for an insulating one. A double-layer aluminum shielding cage can effectively reduce EMPs from 314.21 kV/m to 58.46 kV/m. In contrast, polytetrafluoroethylene (PTFE) is hardly able to withstand the EMP penetration. The simulations are well verified by experimental results. These findings are helpful for developing effective strategies to mitigate EMPs at large laser infrastructure and ensure the safety of experimental setups.