With the advancement of high-intensity laser (HIL) technology, laser-induced plasma can produce short-lived nuclear isomers, which hold significant research value in fields such as nuclear-excitation mechanisms, nuclear clocks and radioactive medicine. However, due to intense electromagnetic pulses (EMPs) and X-rays, the detection of the short-lived isomers is still challenging today. To address this, an optical-fiber-coupled scintillator detection method is proposed in this study. The method can overcome the dilemma that traditional real-time detection methods face when struggling with the complex electromagnetic and radiation environment generated by HIL experiments, enabling real-time detection of characteristic signals on the nanosecond time scale during experiments. Employing a PW-level femtosecond laser-pumping ${}^{83}$Kr to the $7/2+$ metastable state, which has a half-life of 156.94 ns, the de-excitation gamma-rays were detected successfully by the proposed detection system for the first time. This method addresses critical challenges in EMP-dominated HIL environments, enables investigations of ultra-fast nuclear processes and further advances experiments related to high-repetition-rate intense lasers.

The generation of intense radio-frequency and microwave electromagnetic pulses (EMPs) by the interaction of a high-power laser with a target is an interesting phenomenon, the exact mechanisms of which remain inadequately explained. In this paper we present a detailed characterization of the EMP emission at a sub-nanosecond kilojoule laser facility, the Prague Asterix Laser System. The EMPs were detected using a comprehensive set of broadband diagnostics including B-dot and D-dot probes, various antennas, target current and voltage probes and oscilloscopes with 100 and 128 GS/s sampling. Measurements show that the EMP spectrum was strongly dependent on the laser energy: the maximum frequency of the spectrum and the frequency of the spectrum centroid increased with increasing laser beam energy in the signals from all detectors used. The highest observed frequencies exceeded 9 GHz. The amplitude and energy of the detected EMP signals were scaled as a function of laser energy, power and number of emitted electrons.

Understanding the physics of electromagnetic pulse (EMP) emission and nozzle damage is critical for the long-term operation of laser experiments with gas targets, particularly at facilities looking to produce stable sources of radiation at high repetition rates. We present a theoretical model of plasma formation and electrostatic charging when high-power lasers are focused inside gases. The model can be used to estimate the amplitude of gigahertz EMPs produced by the laser and the extent of damage to the gas jet nozzle. Looking at a range of laser and target properties relevant to existing high-power laser systems, we find that EMP fields of tens to hundreds of kV/m can be generated several metres from the gas jet. Model predictions are compared with measurements of EMPs, plasma formation and nozzle damage from two experiments on the VEGA-3 laser and one experiment on the Vulcan Petawatt laser.