| 研究課題/領域番号 |
26707031
|
|---|
| 研究機関 | 国立研究開発法人日本原子力研究開発機構 |
|---|
研究代表者 |
PIROZHKOV Alex 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 量子ビーム応用研究センター, 研究副主幹 (00446410)
|
|---|
| 研究期間 (年度) |
2014-04-01 – 2018-03-31
|
| 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 |
|---|
| 研究実績の概要 |
In FY2015 I made a good progress in research on the ultra-bright x-ray harmonic comb by relativistic plasma singularity.
In this 2nd Project year, I concentrated on preliminary experiments, diagnostic development, and our J-KAREN-P laser improvements. I determined the compressor alignment and wavefront accuracies necessary to achieve the Project goals. I made ultra-sensitive compressor alignment system and performed wavefront correction to meet these requirements.
I published a paper about multilayer x-ray mirrors widely used in research on harmonics (Physics-Uspekhi, Impact Factor=2.6). I made 6 oral presentations devoted to the ultra-bright coherent x-ray source at 3 international and 3 domestic conferences. My presentations are accepted as Invited at 2 international conferences.
|
| 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
(1) According to my experimental data obtained before this Project, the harmonic generation efficiency strongly depends on focal spot quality characterized by the Strehl ratio, i.e. ratio of achieved intensity to the diffraction-limited one. For Strehl ratio >0.5, I calculated the required accuracy of the compressor alignment, which turned out to be 10 urad for all 12 axes (4 diffraction gratings x 3 angles), and maximum allowed wavefront error, which should be well below 100 nm.
(2) With standard techniques, the above accuracies were not attainable. To achieve them, I participated in improvement of our Institute's J-KAREN-P laser. In particular, I headed the development and implementation of a special compressor alignment system with the sensitivity of a few urad, sufficient for the specified goals. I made the high-quality laser beamline which provides wavefront error down to 90 nm and narrow-band Strehl ratio of ~0.3 with the record value of 0.5. I led the compressor alignment and achieved the on-target pulse duration of 30 fs.
(3) I designed and purchased filtered Ce:YAG scintillators for use as high-resolution detectors in x-ray imaging and spectroscopy. I designed innovative high spatial and spectral resolution XUV spectrograph based on varied-linespace (VLS) diffraction grating for precise aberration correction. I contacted two manufacturers, HORIBA Jobin Yvon and Shimadzu Corporation. They told that manufacturing would take not shorter than 6 months, so I decided to postpone the purchase in order to complete it within a single fiscal year of FY2016.
|
| 今後の研究の推進方策 |
(1): Orders. I will order the VLS grating (postponed purchase) and assemble the new high spatial and spectral resolution XUV spectrograph. I will also order optical blocking filters (made by Lebow and GoodFellow) and additional supersonic nozzles (Kyoto Takaoshin). These will be necessary because both filters and nozzles need to be replaced every several weeks of experiments.
(2): Laser. During experiments in FY2015 I found problems in the deformable mirror software which make wavefront correction very time-consuming. The deformable mirror manufacturer acknowledged these problems and is ready to solve them. With the modified software I plan to achieve better wavefront quality and Strehl ratio >0.5. I will also measure and remove the possible angular chirp so that it will not degrade the spot quality.
(3): Experiments. I will perform experiments with our J-KAREN-P laser in accordance with the Proposal, i.e. experiments on the control and enhancement of harmonics generation using the density tailoring and focal spot shaping. In these experiments I will widely use new equipment purchased and developed during this Project, including spectrographs and high-resolution soft x-ray imagers. I expect to achieve or closely approach the Project goals.
(4): Collaborations. There may be a possibility to perform experiment using high-power laser abroad with my foreign collaborators (Prof. D. Neely, CLF RAL, UK, 0.5 PW Astra Gemini laser; Drs. I. W. Choi and I. J. Kim, APRI GIST, Korea, PW laser).
|
| 次年度使用額が生じた理由 |
Originally, I planned to order the manufacturing and to purchase the VLS grating for novel high-resolution XUV spectrograph in FY2015. However, the prospective manufacturers, HORIBA Jobin Yvon and Shimadzu Corporation, explained that the manufacturing requires at least 6 months, so I decided to postpone the purchase in order to complete it within a single fiscal year of FY2016.
|
| 次年度使用額の使用計画 |
I plan to order the VLS diffraction gratings for the XUV spectrograph, the estimated price is ~2,000,000 to ~3,000,000 yen. This high-resolution spectrograph will be used in experiments to deepen my understanding of the coherent x-ray emission from relativistic plasma singularities.
|
