远紫外感应电荷交叉延迟线阳极光子计数成像探测器关键技术研究

Currently, the ultraviolet (UV) photon-counting imaging detector with microchannel plate (MCP) and two-dimensional position-senstive anode have important applications and urgent need in many fields such as space astronomy, space weather forecast, space remote sensing, deep space exploration and electrooptical countermeasures and so on. In order to solve smoe difficult problems on the image nonlinearity which come from the redistribution of charge by secondary electron emission from the surface of the anode into the gap between the anode and MCP stack, we introduce a kind of far ultraviolet (FUV) photon-counting imaging detector based on an induced-charge cross delay line (XDL) anode, the detector use a resistive anode to collect electron cloud from MCP stack and produce induced charge on XDL anode behind the resistive anode, this will improve both space resolution, total count rate, time resolution and produce the image with good linearity due to preventing MCP stack's electron cloud from directly falling on the XDL anode. We will succeed in developing the photon-counting imaging detectors in far-ultraviolet(FUV) 115nm-180nm band after overcoming some key technical problems such as the fabrication of the cathode with high efficiency quantum, the manufacture of induced charge cross dalay line anode with good performances and the development of position readouts with high signal-to-noise ratio (SNR), this will be the fundamental research for this kind of detector which will be used in space appliactions in the future.

目前，使用微通道板（MCP）和二维位置灵敏阳极的紫外光子计数成像探测器在我国空间天文学、空间天气预报、空间遥感、深空探测、光电对抗等领域有重要的应用背景及迫切需求。为解决现有的探测器由于MCP的电子云在金属阳极上产生的二次电子导致的图像非线性及不稳定性，本项目提出了一种具有感应电荷交叉延迟线（XDL）阳极的远紫外（FUV）光子计数成像探测器，它利用一个电阻阳极直接收集来自MCP的电子云，同时在其后面的XDL阳极上产生感应电荷，既提高了XDL阳极的空间分辨率、计数率等性能，又避免了电子云直接与XDL阳极作用产生的二次电子所导致的图像非线性。拟通过解决高量子效率FUV波段光电阴极制备、高性能感应电荷XDL阳极制作、高信噪比位置读出电路的研制等关键技术，研制波长范围115nm-180nm的光子计数成像探测器，为未来空间应用做前期基础性研究。

完成了具有CsI光阴极和感应电荷交叉延迟线（XDL）阳极的近紫外（FUV）光子计数成像探测器的研制工作，该探测器包括氟化镁窗口、镀有CsI光阴极的MCP堆组成的密封管体、位于管体外部的感应电荷XDL阳极和位置读出电路及相应的图像实时采集和处理软件等几部分。首先，设计和制备了具有反射式CsI光阴极的光子计数成像探测器的密封管体，每片平面MCP的直径33mm、有效口径25mm、长径比60：1、通道直径12.5um，两片MCP构成V型结构。CsI光电阴极制备MCP的前表面，电阻阳极位于密封管体内部，其方块电阻为100兆欧~200兆欧。其次，完成了感应电荷XDL阳极的仿真设计与制备，所设计XDL阳极采用埋藏式结构，低层延迟线被绝缘介质层所覆盖，所设计阳极有效面积为46mmX46mm，阳极周期为0.6mm，上层延迟线宽0.2mm，下层延迟线宽0.4mm。仿真时，上层延迟线可以看作“微带线”结构，而下层延迟线可以认为是“带状线”结构。仿真结果表明：上层延迟线的延迟时间约为32ns，下层延迟线的延迟时间约为37ns，上线层延迟线的衰减分别为：-1.94dB和-3.6dB，输出脉冲无反射和串扰，阻抗50欧姆。使用丝网印刷技术制备了感应电荷XDL阳极，实测结果表明上下层的延迟时间分别为35.4ns及46.8ns。再次，完成了位置读出电路的研制工作。该位置电路包括包括四路低噪声射频放大器、四路恒比鉴别器（CFD）、FPGA控制及其接口电路及计算机系统。位置读出电路的时间测量范围40us，时间分辨率27ps。最后，对探测器的空间分辨率、暗计数率、图像线性、光阴极量子效率及最高计数率进行了检测，检测结果表明：各项技术指标均满足要求。