基于Mo丝X-Pinch高能辐射的脉冲X射线光栅干涉成像技术研究

X-ray point-projection imaging is an important and widely used method to non-destructively probe transient properties of matters. However, the weak absorption nature of low-Z materials causes the x-ray absorption images of them have very poor quality with respect to recognize the boundary of different components. This disadvantage has made it impossible for lots of scientific research, such as evolution of internal cavities of energetic materials, liquid injection and so on. The X-ray grating interferemeter is a newly-developed technology which can detect and separate different imaging contrast. Taking it into account that X-Pinch x-ray source has the ability to produce 10-30 keV pulsed x-ray radiations. So, it will be very useful if one can combine the X-Pinch x-ray sources and the x-ray grating interferemeters together for the detection of transient images. Since by doing this, it could take the advantage of X-Pinch sources such as easy to construct and low cost,and also effectively increase the image contrast. This proposal aims to make such a fancy technology into reality. To do this, the parameters of high-energy x-ray radiations from Mo wire X-pinches will be measured to find optimized working conditions for X-Pinch sources, and researches on how to build an x-ray grating interferemeter which is compliment with the environment of X-Pinch discharges will be conducted .It is believed that the successful execution of this study will produce an advanced transient x-ray imaging technology which will greatly benefit the researches of dynamic process of low-Z matters.

X射线辐射成像目前研究物质瞬态变化过程的重要诊断技术。然而，低Z材料对X射线有限的衰减能力导致吸收衬度图像对物质界面及轮廓的呈现能力不足，制约了诸如含能材料内部孔洞演化、液体喷射等动态过程的研究。X射线光栅干涉是近年出现的能够探测并分离多种衬度的成像技术。X-Pinch光源具备产生能量较高的10-30 keV脉冲X射线的能力。将X-Pinch光源与光栅干涉成像技术结合起来用于瞬态成像，既能发挥X-Pinch结构简单、成本低的特点，又能有效提升图像的对比度，具有广阔的应用前景。本项目拟在获取Mo丝X-Pinch 高能辐射主要特征参数及其随电流和丝负载参数的变化规律的基础上，研究适应X-Pinch光源工作环境的光栅干涉成像系统的设计方法，实现基于X-Pinch光源的瞬态X射线光栅干涉成像，为低Z材料动态过程的图像诊断提供一种高效实用的解决方案。

本项目针对低Z物质瞬态过程实验研究对高对比X射线透射照相技术的需求，开展了基于X-Pinch光源的光栅干涉瞬态照相技术研究，内容包括Mo丝X-Pinch高能脉冲辐射特性测量、17.4 keV紧凑X射线光栅干涉仪的设计、调试和数据处理方法等。本项目初步建立了基于X-Pinch光源的瞬态光栅干涉成像能力，获得了低速喷射水柱的瞬态摩尔条纹图像，经进一步完善后有望用于燃油喷雾、高密度等离子体和轻重物质混合射流的精密诊断。此外，本项目对光栅干涉系统摩尔条纹可见度的生成机制进行了理论分析，建立了摩尔条纹可见度的数学模型并利用已有成像系统进行了验证，为瞬态多衬度成像系统设计提供了重要的理论依据。提出了基于加权1范数的非线性正则化相位复原方法，具有复原图像边界光滑、信噪比高的优点，对于定量分析、不同衬度图像比较、图像融合等具有积极意义。