| 研究課題/領域番号 |
19H00669
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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, 上席研究員(定常) (00446410)
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| 研究分担者 |
難波 愼一 広島大学, 工学研究科, 教授 (00343294)
Esirkepov Timur 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, 上席研究員(定常) (10370363)
匂坂 明人 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) (20354970)
小倉 浩一 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) (30354971)
Pikuz Tatiana 大阪大学, 先導的学際研究機構, 特任准教授(常勤) (20619978)
Koga James 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, 専門業務員(任常) (70370393)
桐山 博光 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, グループリーダー(定常) (40354972)
神門 正城 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, グループリーダー(定常) (50343942)
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| 研究期間 (年度) |
2019-04-01 – 2024-03-31
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| キーワード | Coherent x-ray source / New imaging paradigm / BISER / Relativistic plasma / Plasma singularities |
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| 研究実績の概要 |
During the 1st Project year, we started the active development of experimental methods and diagnostics necessary to accomplish the Project Goals. Simultaneously, we achieved several important research results:
We improved the laser temporal shape/contrast by introducing wedged optics through the amplifier chain. This will result in weaker plasma heating and sharper singularities, resulting in brighter BISER. By careful design of the self-compensating multi-pass scheme, the wedge effect on the focal spot was minimized to ensure a high BISER photon yield. [Kiriyama et al., Opt. Lett. 45 1100 (2020)].
We demonstrated by PIC simulations that despite nanoscale size and relativistic velocity, the plasma singularities can be detected via ultrashort (~10 fs) optical probe. This will greatly contribute to our planned experiments as we will implement this method to detect the location and topology of the singularities and correlate them with coherent BISER radiation. [Esirkepov et al., Phys. Plasmas 27 052103 (2020) - published in May, will be formally included in the FY2020 report].
We experimentally tested a new regime of much higher plasma density (~10^22-10^23 cm^-3) and laser intensity (~10^21-10^22 W/cm^2) to further increase the x-ray photon number. We obtained a number of important results, including dependences of the hard x-ray generation on the plasma thickness which will allow us to distinguish the Bremsstrahlung from Gamma Flash mechanisms, plasma characterization with x-ray spectroscopy, and bright coherent x-ray generation (high-order harmonics).
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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
We started active development of experimental methods & diagnostics necessary to accomplish the Project Goals. Method (L): Laser Control (Co-I: Hiromitsu Kiriyama): We improved the laser temporal shape/contrast which will result in sharper singularities and brighter BISER.
Method (O): High-Resolution Optical Diagnostics (Co-Is: Koichi Ogura, Masaki Kando). To achieve the Goal #1 (increase the photon number and energy with the On-axis BISER), we will need precise diagnostics of plasma singularities. For this, we developed one of the two critical diagnostics - a ~μm resolution optical imaging, "Top View".
Method (X): X-ray Diagnostics (Co-Is: Akito Sagisaka, Tatiana Pikuz, Shinichi Namba, RC: Masato Koike). We acquired additional x-ray CCD, designed and acquired adapter flanges for our 3-channel flat-field spectrograph, and started the design of a high-resolution Varied-Line-Space (VLS) diffraction grating optimized for our experimental setup and the 1-2 keV spectral range. We started the design of the Photoelectron and Auger spectroscopy beamline.
Theory & Simulations (Co-Is: Timur Esirkepov, James Koga): We demonstrated by PIC simulations that the relativistic plasma singularities can be detected via ultrashort optical probe. We simulated the gas flow through supersonic nozzles used in experiments.
In parallel with the theory/simulations and diagnostics development, we performed a pioneering experiment to test much higher plasma density (~10^22-10^23 cm^-3) and laser intensity (~10^21-10^22 W/cm^2) to further increase the x-ray photon number.
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| 今後の研究の推進方策 |
In FY2019, the new coronavirus had little effect on the Project, except work limitations in March. The new coronavirus actually emphasized the importance of our Goals, namely future attosecond lensless imaging, which potentially will result in quick imaging of unknown viruses. However, in FY2020, we foresee some impact of the pandemic and quarantine on the research. This includes limited access to the lab in April and May, difficulties in purchasing and especially manufacturing new equipment, etc. However, for now we hope to resume the normal research from June.
In accordance to the Project Plan and Goals, we will continue the Methods & Diagnostics development: (O): High-Resolution Optical Diagnostics (Co-Is: Koichi Ogura, Masaki Kando): we will develop the 2nd critical diagnostics, high-resolution optical Schlieren probe.
Method (X): X-ray Diagnostics (Co-Is: Akito Sagisaka, Tatiana Pikuz, Shinichi Namba, RC: Masato Koike). We plan to finish the development of the VLS grating for 1-2 keV range and the Photoelectron and Auger beamline.
Theory & Simulations (Co-Is: Timur Esirkepov, James Koga): We will continue PIC simulations for guiding the methods development and experiments. We will perform gas dynamic simulations for our supersonic nozzle + blade system.
We plan to perform an experiment where we will employ the Methods and Diagnostics developed earlier. In particular, we plan to achieve the Filamentation and Self-Focusing control and detect the singularities with new optical diagnostics, and correlate their properties with BISER radiation.
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