@misc{oai:repo.qst.go.jp:00081437,
 author = {Pirozhkov, Alexander and Sagisaka, Akito and Ogura, Koichi and Timur, Esirkepov and Gonzalez izquierdo, Bruno and N. Shatokhin, A. and A. Vishnyakov, E. and Armstrong, C. and A. Pikuz, T. and A. Alkhimova, M. and A. Pikuz, S. and Yan, W. and M. Jeong, T. and Singh, S. and Hadjisolomou, P. and Finke, O. and Grittani, G. and Nevrkla, M. and Lazzarini, C. and Velyhan, A. and Hayakawa, Takehito and Fukuda, Yuuji and Kevin Koga, James and Ishino, Masahiko and Kondo, Kotaro and Miyasaka, Yasuhiro and Kon, Akira and Nishikino, Masaharu and O. Kolesnikov, A. and N. Ragozin, E. and Khikhlukha, D. and P. Tsygvintsev, I. and A. Gasilov, V. and Kumar, D. and Nejdl, J. and Margarone, D. and Sasorov, P. and Weber, S. and Kando, Masaki and Kiriyama, Hiromitsu and Korn, G. and Neely, D. and Kondo, Kiminori and Bulanov, Sergey and Kawachi, Tetsuya and Pirozhkov, Alexander and Sagisaka, Akito and Ogura, Koichi and Timur, Esirkepov and Gonzalez izquierdo, Bruno and Hayakawa, Takehito and Fukuda, Yuuji and Kevin Koga, James and Ishino, Masahiko and Kondo, Kotaro and Miyasaka, Yasuhiro and Kon, Akira and Nishikino, Masaharu and Kando, Masaki and Kiriyama, Hiromitsu and Kondo, Kiminori and Bulanov, Sergey and Kawachi, Tetsuya},
 month = {Dec},
 note = {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.
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[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 2020},
 title = {X-ray generation at intensities approaching 10^22 W/cm^2},
 year = {2020}
}