M. M. Nazarov, P. A. Shcheglov, A. A. Garmatina, M. V. Chashchin, Z. Ch. Margushev, K. A. Bzheumikhov, A. V. Mitrofanov, D. A. Sidorov-Biryukov, A. M. Zheltikov, V. M. Gordienko, V. Ya. Panchenko
- National Research Centre “Kurchatov Institute”, Moscow
- Federal State Budget Scientific Establishment “Federal Scientific Center “Kabardino-Balkarian Scientific Center of the Russian Academy of Sciences”, Nalchik
- Institute on Laser and Information Technologies, Branch of the Federal Research Centre ‘Crystallography and Photonics’
- Russian Quantum Center, Skolkovo, Moscow
- Faculty of Physics, Lomonosov Moscow State University
- Department of Physics and Astronomy, Texas A&M University
Abstract: We demonstrate experimentally that when a copper foil is exposed to femtosecond sub-relativistic laser pulses, the intensities characteristic X-rays (XRs), terahertz (THz) radiation, and the second optical harmonic increase simultaneously with decreasing foil thickness. The generation efficiency of XRs and THz radiation, as well as of the 3/2 harmonic, depends with different degrees of nonlinearity on the laser pulse intensity and duration. The general behaviour of the measured signals is determined by the two-plasmon decay instability, the contribution of hot electrons and their recirculation in the observed processes.
Keywords: characteristic X-rays, terahertz radiation, electron recirculation, sub-relativistic intensity.
Received: 24.05.2022