@misc{oai:repo.qst.go.jp:00066551,
 author = {ピロジコフ, アレキサンダー and ピロジコフ アレキサンダー},
 month = {Sep},
 note = {J-KAREN-P [1] is a high-intensity laser facility aiming at the highest beam quality and the highest irradiance for performing state-of-the art experiments at the frontier of modern science, including laser ion and electron acceleration, bright coherent x-ray generation, etc.
We have recently approached the physical limits of the beam quality: diffraction limit of the focal spot and bandwidth limit of the pulse shape [2]. In particular, we have measured the focal spot obtained with an f/1.3 off-axis parabolic mirror during 0.3 PW operation. The laser beam was attenuated by ten wedges with high surface quality confirmed with interferometry. The resulting focal spot had the effective radius of ~1.0 um and the Strehl ratio of ~0.5. We thus achieved the at-focus peak irradiance of ~10^22 W/cm^2, the highest accurately estimated irradiance demonstrated to date.
We have also performed full-beam duration measurement, down-collimating the 280 mm beam to a few mm diameter using a telescope consisting of the main f = 2 600 mm and additional f = 25.4 mm off-axis parabolic mirrors. The full-beam pulse duration and shape were nearly identical to the duration and shape measured using a few mm diameter pick-off, confirming high spatiotemporal quality of the beam and absence of spatiotemporal couplings.
\nIn the second part of my talk, I will present our results on coherent x-ray generation by relativistic electron spikes [3,4] and the Burst Intensification by Singularity Emitting Radiation (BISER) mechanism. I will present the discovery, new model development, model and theory predictions, and these prediction confirmations in our experiments, as well as the future outlook.
\n[1].    H. Kiriyama, M. Mori, A. S. Pirozhkov, K. Ogura, A. Sagisaka, A. Kon, T. Zh. Esirkepov, Y. Hayashi, H. Kotaki, M. Kanasaki, H. Sakaki, Y. Fukuda, J. K. Koga, M. Nishiuchi, M. Kando, S. V. Bulanov, K. Kondo, P. R. Bolton, O. Slezak, D. Vojna, M. Sawicka-Chyla, V. Jambunathan, A. Lucianetti, and T. Mocek, "High-Contrast, High-Intensity Petawatt-Class Laser and Applications," IEEE J. Sel. Topics Quantum Electron. 21, 1601118-18 (2015).
[2].    A. S. Pirozhkov, Y. Fukuda, M. Nishiuchi, H. Kiriyama, A. Sagisaka, K. Ogura, M. Mori, M. Kishimoto, H. Sakaki, N. P. Dover, K. Kondo, N. Nakanii, K. Huang, M. Kanasaki, K. Kondo, and M. Kando, "Approaching the diffraction-limited, bandwidth-limited Petawatt," Opt. Express 25, 20486 (2017).
[3]. A. S. Pirozhkov, et al., "Soft-X-Ray Harmonic Comb from Relativistic Electron Spikes," Phys. Rev. Lett. 108 (13), 135004-5 (2012).
[4]. A. S. Pirozhkov, et al., "High order harmonics from relativistic electron spikes," New J. Phys. 16 (9), 093003-30 (2014)., Japan-US Technical Meeting on High Energy Density Sciences},
 title = {J-KAREN-P Laser: Approaching the diffraction-limited, bandwidth-limited Petawatt},
 year = {2017}
}