Generation of bright sources of hard and soft x-rays is one of the most promising applications of high-power lasers. We report on our first experiment on achieving ultra-high on-target intensities, reaching efficient conversion of laser radiation to hard x-rays (towards the "Gamma Flash" regime [1-3]), and generating intense high-order harmonics [4]. Our international team (Japan, Czech Republic, Russia, UK) used the J-KAREN-P laser facility at KPSI QST, Japan [5-8] and irradiated solid targets with intensities close to 1022 W/cm2. We employed a broad range of diagnostics, including laser, plasma, secondary radiation (from NIR to MeV x-rays) and particle (e-, p+) diagnostics, and controlled the preplasma scale length, which is a critical parameter for both hard x-ray [1,3] and harmonic generation [4]. Here we overview the experiment and dedicated simulations, and show first results on hard x-ray and harmonic generation, x-ray spectroscopy, and preplasma analysis.We thank the J-KAREN-P laser operation group. We acknowledge financial support from ELI-Beamlines, High Field Initiative Project (CZ.02.1.01/0.0/0.0/15\_003/0000449) from the European Regional Development Fund, JSPS JP 17F17811 and 19H00669, QST-IRI, and QST Director Funds 創成的研究#16 and #20.[1]T. Nakamura, et al., Phys. Rev. Lett., 2012, 108 195001.[2]C. P. Ridgers, et al., Phys. Rev. Lett. 2012, 108, 165006.[3]K. V. Lezhnin, P. V. Sasorov, G. Korn, and S. V. Bulanov, Phys. Plasmas, 2018, 25, 123105.[4]U. Teubner and P. Gibbon, Rev. Mod. Phys., 2009, 81, 445.[5]A. S. Pirozhkov, et al., Opt. Express, 2017, 25, 20486.[6]H. Kiriyama, et al., Opt. Lett., 2018, 43, 2595.[7]H. Kiriyama, et al., Opt. Lett., 2020, 45, 1100.[8]H. Kiriyama, et al., Crystals., 2020, 10, 783.International Conference on X-Ray Laser 202
