Link do spotkania w aplikacji Microsoft Teams: https://tiny.pl/2rb65r5k

Abstract

The interaction of laser radiation with solid matter at intensities above 10¹⁵ W/cm² gives rise to the ionization of matter, creating plasma on the surface of the target, and leads to production of accelerated particles and X-ray photons. In the experiment at the Prague Asterix Laser System (PALS), the hot electrons and bremsstrahlung are characterized from the interaction of sub-nanosecond and kilo-joule class laser pulse with thin metal foil targets of different materials (Cu, Ta, Ti, Sn, Pb). The laser intensity varied between 4 × 10¹⁵ and 3 × 10¹⁶ W/cm² at the target focus however target thickness was chosen in the range of 1–100 μm. The energy distribution functions of electrons were measured by an angular array of magnetic spectrometers indicating the electron temperature in the range between 30 keV and 80 keV. The bremsstrahlung spectrum was characterized using a scintillator-based spectrometer. The experimental results reveal the temperature scaling and instability threshold in hot electron and bremsstrahlung radiation. In addition, the measured data show the laser-energy scaling of the total flux of hot electrons in the forward and backward directions with respect to the laser vector and conversion efficiency of the laser energy to the energy carried by hot electrons. Moreover, the temperature of hot electrons as well as the unfolded bremsstrahlung temperature using a Monte Carlo code found to be consistent with signals of the scintillator detector. The intensity scaling shows that the electron flux increases discontinuously with increasing laser intensity from ∼1−2 × 10¹⁶ W/cm² with the consequent of parametric instabilities in the production of hot electrons. For the given laser and target parameters, the nonlinear behavior of observed signal and relevant physics are also described in detail.