| 研究課題/領域番号 |
26707031
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| 研究機関 | 国立研究開発法人量子科学技術研究開発機構 |
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研究代表者 |
PIROZHKOV Alex 国立研究開発法人量子科学技術研究開発機構, 関西光科学研究所 光量子科学研究部, 主幹研究員(定常) (00446410)
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| 研究期間 (年度) |
2014-04-01 – 2018-03-31
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| キーワード | コヒーレントX線放射 / レーザー光の高次高調波 / 相対論的電子スパイク / レーザー光とプラズマの相互作用 / 超高強度レーザー / 相対論的プラズマ |
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| 研究実績の概要 |
In FY2016 I made a good progress in research on the ultra-bright x-ray harmonic comb by relativistic plasma singularity, in accordance with the research plan.
I tuned our J-KAREN-P laser and achieved record performance, including the Strehl ratio of ~0.5, rarely achieved with high-power lasers. I designed, ordered, and tested novel Varied Line Space (VLS) diffraction gratings for XUV and soft x-ray spectral regions. I started experiments with our upgraded J-KAREN-P laser.
I generalized the concept of coherent x-ray emission by relativistic singularities and formulated the 'Burst Intensification by Singularity Emitting Radiation' (BISER) concept, which is a conceptual advance and a new fundamental and general insight in physics. I wrote the paper describing this concept and proving it experimentally [Pirozhkov et al., arXiv:1611.05547 (2016)], now under submission.
I wrote a refereed proc. paper about recent experimental data and the driving laser parameters required for efficient harmonic generation [Pirozhkov et al., "High-Order Harmonic Generation by Relativistic Plasma Singularities: the Driving Laser Requirements," Springer Proc. Phys. (accepted)].
I made 7 presentations devoted to this research (2 invited and 2 oral presentations at international conferences and 1 oral and 2 poster presentations at domestic conferences).
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
In accordance with the plan, I designed novel VLS diffraction gratings with very large groove density variation from 1100 to 2300 lines/mm. This compensates astigmatism of a large-diameter focusing spherical mirror and allows making a soft x-ray spectrograph with large acceptance angle and high spatial and spectral resolutions indispensable for this research. I ordered the grating and tested its performance at the KEK PF synchrotron.
According to the plan and based on my previous year results, I achieved record performance of our J-KAREN-P laser: bandwidth-limited pulse duration, Strehl ratio of 0.5, and zero angular chirp. Importantly, I measured the focal spot at the ultra-high power of 0.3 PW using 10-wedge attenuation after amplifiers, and measured the full beam duration using down-collimation of the 280 mm diameter beam down to 3 mm with two off-axis parabolic mirrors. These gave unprecedented accuracy of the pulse and spot characterization. I started the experiments with the upgraded J-KAREN-P laser.
I formulated the BISER concept, which states that if a medium with multi-stream flow emits traveling waves of any nature, these will result in appearance of density spikes (singularities) and can result in extreme enhancement of traveling wave emission due to the coherence. The BISER concept is very general and applicable for laser and astrophysical plasma, acoustics, etc. The harmonics from relativistic electron spikes is a manifestation of BISER. The paper describing BISER and proving it experimentally is now under submission [Pirozhkov et al., arXiv:1611.05547 (2016)].
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| 今後の研究の推進方策 |
I will continue experiments with our J-KAREN-P laser using new devices designed and acquired during this Project: the blade on stable holder and precise motorized positioning for controlled production of shock wave in gas jet, high-resolution large-acceptance-angle spectrograph with VLS grating, and high-resolution imagers with LiF crystal detector and scintillator-based detector.
I plan to achieve the Project goals, i.e. control of ultrabright x-ray harmonic comb using tailoring of the gas jet density profile and laser spot shape. I plan to achieve significant enhancement of photon number in the coherent x-ray beam and higher photon energies. These achievements are likely due to encouraging first experiments, stably operating J-KAREN-P laser, Particle-In-Cell (PIC) simulations performed for this laser-plasma interaction regime, and existing scalings obtained experimentally and theoretically.
During this Project, I obtained (and plan to obtain more) good results concerning the coherent x-ray generation by relativistic plasma singularity, high-power laser tuning, and the very general BISER concept. I will perform additional data processing, as necessary, write papers, and submit them to high-impact refereed journals with the open access possibility.
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| 次年度使用額が生じた理由 |
I purchased all the planned items and paid for all the planned expenses. The remaining money (<1% of the total) is due to spending optimization at the final stage of the FY2016, so I could save some money.
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| 次年度使用額の使用計画 |
I plan to transfer this money to the FY2017 and use them to purchase additional experimental equipment.
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