Patel Shamim, Suggit Matthew J, Stubley Paul G, Hawreliak James A, Ciricosta Orlando, Comley Andrew J, Collins Gilbert W, Eggert Jon H, Foster John M, Wark Justin S, Higginbotham Andrew
Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Rev Sci Instrum. 2015 May;86(5):053908. doi: 10.1063/1.4921774.
In situ white light Laue diffraction has been successfully used to interrogate the structure of single crystal materials undergoing rapid (nanosecond) dynamic compression up to megabar pressures. However, information on strain state accessible via this technique is limited, reducing its applicability for a range of applications. We present an extension to the existing Laue diffraction platform in which we record the photon energy of a subset of diffraction peaks. This allows for a measurement of the longitudinal and transverse strains in situ during compression. Consequently, we demonstrate measurement of volumetric compression of the unit cell, in addition to the limited aspect ratio information accessible in conventional white light Laue. We present preliminary results for silicon, where only an elastic strain is observed. VISAR measurements show the presence of a two wave structure and measurements show that material downstream of the second wave does not contribute to the observed diffraction peaks, supporting the idea that this material may be highly disordered, or has undergone large scale rotation.
原位白光劳埃衍射已成功用于研究在高达兆巴压力下经历快速（纳秒级）动态压缩的单晶材料的结构。然而，通过该技术可获取的应变状态信息有限，这限制了其在一系列应用中的适用性。我们对现有的劳埃衍射平台进行了扩展，在该平台中我们记录了一部分衍射峰的光子能量。这使得在压缩过程中能够原位测量纵向和横向应变。因此，除了传统白光劳埃中可获取的有限的纵横比信息外，我们还展示了对晶胞体积压缩的测量。我们给出了硅的初步结果，其中仅观察到弹性应变。VISAR测量显示存在双波结构，并且测量表明第二波下游的材料对观察到的衍射峰没有贡献，这支持了该材料可能高度无序或经历了大规模旋转的观点。
