| 研究実績の概要 |
In 2018, year the significant progress was achieved in analysis and experimental testing of basic concepts: incoherent (NCCPI scheme) and XFEL (CPPI scheme) radiography.
NCCPI. A) Pico-2000 laser (LULI),80 J, 10 ps. Optimization of backlighter x-ray yield in the range of 4 - 5 keV. Variation of target material (Ti, Ni, Pt, Au), plasma size, target configuration (bulk foil, wire), optical magnification, filtering of LiF detector against debris (static regime).The range of setup parameters allow spatial resolution x< 3 um was determined. B) LFEX laser (ILE), 300J/ beam, 1.5 ps). Significant increase of luminosity (Wire targets, Ti, Pt, Cu) was reached. The x of 3 - 4 um in images of opaque grids was confirmed. Unexpected blurring of x due to scattering of x-ray on high-Z filters has found and need to be investigated. For the first time imaging of RTI (Rayleigh-Taylor Instability) target driven by GEKKO laser pulse was recorded.
CPPI, SACLA XFEL. A) The SAXS experiment without screening of direct probe beam and the highly informative first orders of scattering radiation provided. For the first time diffraction pattern from um-rod target was measured at full dynamic range of 1E6 with x 1 um. The images are perfectly consistent with advanced modeling. B) Imaging characterization of XFEL pump and pump beams in two-color pump-probe experiment. C) In situ precise measurement of 1D and 2D focused XFEL beam caustic.
Metrology of LiF detector properties. The universal dependence of LiF photoluminescence (PL) response on the accumulated dose in the range 0.5-10 keV was found.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
The significant progress of this year research based on numerous experimental results obtained at different facilities. Both developing imaging platforms were tested under various operating conditions. The NCPPI scheme was tested at high power (300J/beam) LFEX laser. At static radiography of test-grids the resolution x 3 um, which much better then size of backlighter source, was confirmed. It was found that the use of filters from medium and high Z materials is limited due to increase of background scattering. Further investigations of this problem will be done. Obtained strongly desired metrological characteristics of LiF detector. For the first time made calibration measurement the coloration efficiency and PL response to the dose of x-ray in the multi-keV range (0.5 - 10 keV). It shown that this response is independent on the photon energy and can be approximated by unique equation. That will allow identical interpretation of radiographic data from independent experiments. The spatial resolution of LiF detector of 1.0 - 1.4 um is found independent of incident photon energy. The record dynamic range of more than 1E6 confirmed in SAXS experiment at SACLA. For the first time SAXS diffraction pattern was recorded without gap around zero and first orders with resolution x 1 um. This result clearly show advances of CPPI scheme for monochromatic radiography of objects with large gradient of density. As a further step it will be applied at BL3 for investigation RTI in dynamic regime. 4 articles published in high ranking journals including Scientific reports.
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| 今後の研究の推進方策 |
1. On the base of study of PL response curve of LiF to the flux and dose of accumulated radiation, completed in the undergoing project, the algorithm of reconstruction the density map of RTI flows from the PL intensity distribution in radiographic snap-shots measured by LiF detector will be developed. This will allow the unique matching the experimental results with simulations.
2. The influence of background thermal radiation from the plasma volume of backlighter source and from the plasma of shock driving laser on the efficiency of colorization of LiF crystal will be investigated theoretically and experimentally. Experiments will be carried out at LULI laser PICO-2000 and ENEA (Frascati) ABC laser. If the effect will be found not negligible, the obtained results will be used for optimization NCPPI scheme to reduce possible degradation of PL signal during measurements.
3. The experiment on phase contrast imaging of Rayleigh-Taylor Instabilities driven by intense ns-laser pulse will be done at SACLA (proved proposal 2019A8037). The CPPI scheme will be applied at the BL3 to observe dynamic of RTI grow for the target with different interface parameters. On the base of preliminary tests, which have also been done at SACLA, BL3 in the frame of current project, the radiographic imaging with micron-size spatial resolution, not reached yet at any other experimental approaches, is expected. According with my knowledges this experiment will be pioneering in the domain of HEDS research.
These results will be submitted as some articles.
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