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39Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2018
ULTRA-INTENSE K-SHELL EMISSION FROM STAINLESS STEEL FOILS IRRADIATED BY FEMTOSECOND LASER PULSES WITH ULTRA-HIGH
INTENSITY (I > 1021 W/CM2)
M.A. Alkhimova1,2,3, A.Ya. Faenov1,2, T.A. Pikuz2,4, I.Yu. Skobelev2,3, S. A. Pikuz2,3 M. Nishiuchi5 , H. Sakaki5, A. S. Pirozhkov5 , A. Sagisaka5, N.P. Dover5, Ko. Kondo5, K. Ogura5, Y. Fukuda5, H. Kiriyama5, T. Esirkepov5, S.V. Bulanov5, M. Kando5, K. Nishitani7,T. Miyahara7, Y. Watanabe7, R. Kodama1,4,6, K. Kondo5.
'Institute for Academic Initiatives, Osaka University, Suita, Osaka, 565-0871, Japan 2Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412, Russia 3National Research Nuclear University «MEPhI»,Moscow, 115409, Russia 4Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871, Japan 5Kansai Photon Science Institute(KPSI), National Institutes for Quantum and Radiological Science and
Technology(QST), Kizugawa, Kyoto, Japan 6Photon Pioneers Center, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan 7Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Japan
We report about x-ray spectroscopy advantages observed at recent experiments on J-
KAREN-P laser facility [1]. The high-resolution X-ray spectroscopic diagnostic was applied to
21 2
observe x-ray emission from dense laser plasma generated via ultra-intense (I ~ 3 x 10 W/cm ) femtosecond laser pulses irradiated thin stainless steel foils. The spectrometer with high spatial resolution equipped by spherically bent mica crystal was implemented to measure X-ray emission from the front and rear sides of target at the wavelength range 1.7 - 2.1 A. We observed the non-liner growth of X-ray emission from stainless steel plasma. X-ray emission intensity increases by power low with laser intensity on target. Laser contrast vs amplified spontaneous emission ration influence on highly charged Fe ions generation was investigated to demonstrate that for effective formation of fast multiply charged ions source in femtosecond laser plasma of medium and heavy chemical elements, laser pulses of ultra-high contrast > 1010 are required. With growth of Z elements, the laser pulse contrast stays the most crucial parameter for x-ray emission and highly charged ion source formation [2].
Also we for the first time demonstrate experimentally from high-intensity laser generated plasma that the highest temperature emission region had electron density ~ 30 times higher than the typically observed critical density for the laser wavelength, corresponding to the value of the relativistic critical density. Kinetic modeling using open access code FLYCHK was provided to estimate main plasma parameters. Assumed that x-ray radiation emits from some plasma regions [3-5] which have notably different parameters and are responsible for the emission of different spectral lines, we obtained a good match between theoretical modelling and experimental measurement.
1. H. Kiriyama et al., "High-Contrast, High-Intensity Petawatt-Class Laser and Applications, "IEEE J. Sel. Top. Quantum Electron 2(1), 232-249 (2015).
2. A. Ya. Faenov et al. "The effect of laser contrast on generation of highly charged Fe ions by ultraintense femtosecond laser pulses," App. Phys. B 123(7), 197 (2017).
3. S.A. Pikuz et al., "Formation of a plasma with the determining role of radiative processes in thin foils irradiated by a pulse of the PEARL subpetawatt laser," JETP Lett. 105(1), 13-17 (2017).
4. S.A. Pikuz Jr. et al., "Production of exotic states of matter with the use of X-rays generated by focusing a petawatt laser pulse onto a solid target," Physics-Uspekhi 57(7), 702 (2014).
5. A.Ya. Faenov. et al., "Nonlinear increase of X-ray intensities from thin foils irradiated with a 200
TW femtosecond laser," Sci. Rep. 5, 13436 (2015).
