Description
Interaction of high-power lasers with matter is accompanied by intense electromagnetic pulses (EMP), which can interfere with diagnostics and damage sensitive electronics, requiring mitigation. At the same time, intense EMPs offer potential for advanced applications. In fundamental plasma physics, laser-driven EMP remains of intrinsic interest, as its generation mechanisms are not yet fully understood.
At the PALS laser facility (1315 nm, 200–300 ps, up to 700 J on target), EMP has been systematically studied for solid, foam, and gaseous targets in both near- and far-field regions. Using a comprehensive broadband diagnostic setup (B-dot and D-dot probes, antennas, target current and voltage probes, low-loss cables, and oscilloscopes with 100 GS/s sampling rate and 33 GHz bandwidth), we observed an exceptionally broad EMP spectrum extending up to 20 GHz. Both peak and centroid frequencies strongly depend on laser intensity, determined by pulse energy and focal spot size, for both polarizations.
At maximum intensities (~2 × 10¹⁷ W/cm²), the neutralization current reached 10 kA. Far-field antenna measurements indicate a total emitted multi-GHz EMP power on the order of GW, corresponding to ~0.1% of the laser pulse energy. The electric field strength at 1 m from the target reached approximately 1 MV/m.
The observed spectral dependence on laser intensity suggests that EMP generation is closely related to plasma dynamics and electron oscillations, whose energy distributions are strongly intensity-dependent.
This research is supported by the Grant Agency of the Czech Republic (Grant No. GM23 05027M), Czech Republic’s Ministry of Education, Youth and Sports project Prague Asterix Laser System (LM2023068) and the EUROfusion Consortium - Euroatom Research and Training Program (Grant No.101052200-EUROfusion). The involved teams have operated within the framework of the Enabling Research Project AWP24-ENR-IFE.02.CEA-01 “Magnetized ICF”.
[1] J. Cikhardt, P. W. Bradford, M. Ehret, S. Agarwal, M. Alonzo, et al:
Comprehensive characterization of electromagnetic pulses driven by a sub-nanosecond kilojoule laser, High Power Laser Science and Engineering 13, e57 (2025)
[2] V. Horká-Zelenková, J. Krása, M. Toufarová, J. Cikhardt, P. Devi, et al: “Electromagnetic pulses, optical emission and chemical change associated with high-power laser-induced dielectric breakdown of gaseous sulphur hexafluoride”, High Power Laser Science and Engineering 13, e77 (2025)
[3] P Rączka, J. Cikhardt, M. Pfeifer, J. Krása, M. Krupka, et al:
“Measurement of strong electromagnetic pulses generated from solid targets at sub-ns kJ-class PALS laser facility”,Plasma Phys. Control. Fusion 63, 085015 (2021)
[4] J. Cikhardt, J. Krása, S. Agarwal, M. Alonzo, P.W. Bradford,
M.Červeňák, et al: “Study of electromagnetic pulses with frequencies exceeding 10 GHz at the kilojoule sub-nanosecond laser facility PALS”, submitted to Plasma Phys. Control. Fusion in November 2025