用于高能量密度物态及惯性约束核聚变诊断的新型高能电子成像关键技术研究

惯性约束核聚变(ICF)和高能量密度物理（HEDP）的研究亟需一种可精确提供物质内部状态信息的实时反馈系统，因此本项目提出，研究设计一套高能电子透镜成像诊断系统，实现对高能量密度物质及惯性约束聚变流体过程的四维瞬态立体成像，时间分辨在皮秒至纳秒量级，三维空间分辨达微米量级。其成像原理是：高能电子束透射靶物质时，由于多重库伦散射的作用，电子束散射角度的分布与物质面密度相关；富含靶物质信息的透射电子束通过点对点成像系统，在荧光靶上成像，获得靶物质内部信息。主要研究内容包括：1、高能电子束与密致物质作用机制及其成像系统空间分辨率的研究； 2、研究利用新型电子加速器提供成像系统所需的电子束脉冲串；3、模拟HEDP靶物质的状态，实现动态成像，进行时间分辨的研究；4、利用新型高频偏转腔技术，实现电子束脉冲串的分束。

High energy density physics (HEDP), particularly inertial confinement fusion (ICF), is becoming a critical research area for development of future energy solutions. Recent activities show that in order to achieve the desired high energy density for fusion research, it would be extremely useful to have an advanced diagnostics system available for providing real time measurements of the internal compressed target matter on a time scale of nanoseconds. We propose here a high resolution spatial-temporal imaging diagnostic system, based on a photocathode based high energy electron linear accelerator, to measure the compression processes in the implosion of an ICF fuel pellet or in other HEDP experiments with a spatial resolution of < 1 µm and a time resolution in the picosecond to nanosecond range. The system employs an electron bunch train (containing a number of short bunches separated by the desired time sampling interval and spatial separation) that penetrates the fast time varying high density target. By imaging the scattered electrons that carry the target information with a high resolution magnetic lens, the detailed target profile and its density evolution can be accurately measured. In order to design and construct the imaging system, we plan to study several important topics: 1) high energy electron interaction with dense matter and its implication for the spatial resolution of the imaging system; 2) the electron linac specification for the high energy density target imaging system; 3) electron beam optics that can accurately transport the scattered electrons to image the target, including arbitrary spatial and temporal beam pattern generation; and 4) verifying the time and spatial resolution of the imaging system using an existing accelerator at Tsinghua University.