Ultrafast time-resolved in situ observation of shock-compressed materials using X-ray free electron laser

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K05714
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Japan Synchrotron Radiation Research Institute
• Principal Investigator: Tange Yoshinori 公益財団法人高輝度光科学研究センター, 回折・散乱推進室, 主幹研究員 (70543164)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 衝撃圧縮 / X線自由電子レーザー / その場観察 / X線回折 / 岩石鉱物

Outline of Final Research Achievements

X-ray free electron lasers allow us to carry out ultrafast time-resolved X-ray diffraction measurements due to its short pulse width of less than ten femtoseconds. We have investigated deformation, structural transition, and fracture of materials under pressure on the basis of the combination of the ultra-fast X-ray diffraction measurements and the laser-induced shock compression experiments. A high-power laser with the pulse width of several nanoseconds reproduces shock-compressed state inside materials, and the generated shock waves propagated in the material transmitting stress for several nanoseconds. By varying the relative exposure timing between the high-power laser and the X-ray free electron laser, time-resolved pump and probe observations were conducted with the time resolution of less than one nanosecond. Based on the time-resolved in situ observation techniques, we observed uniaxial stress propagation in the materials above the elastic limit and its time evolution.

Free Research Field

高圧地球科学

Academic Significance and Societal Importance of the Research Achievements

地球惑星構成物質としてのみならず材料科学分野でも基礎的な物質である酸化アルミニウムと酸化マグネシウムを試料としたレーザー衝撃圧縮実験を行い、X線自由電子レーザーを用い衝撃圧縮過程におけるそれらの構造変化を時分割X線回折測定によって観察した。弾性限界を超えた高応力下でも高い歪み速度においては、圧縮と引張の両状態において物質が差応力を保持することを明確に観察し、国内外の学術会議で報告した。