【作者】 盛立志；

【导师】 赵宝升；

【作者基本信息】 中国科学院研究生院（西安光学精密机械研究所） ， 物理电子学， 2013， 博士

【摘要】 随着卫星导航技术的发展和对自主导航日益迫切的要求，近几年各航天大国都在X射线脉冲星导航研究领域开展了大量研究工作，该方法的可行性已经得到了国际导航届的认可。本文在调研、分析国内外研究进展的基础上，重点研究了脉冲星导航地面模拟系统的方案及关键技术。在进行X射线脉冲星导航空间搭载试验和未来脉冲星导航系统应用之前，为了研究X射线脉冲星导航的相关关键技术，必须在地面搭建实验系统，将空间试验所要进行的X射线光子的探测、光子到达时间的确定、脉冲轮廓的累积、定位精度的计算以及轨道控制等在地面均进行相关研究和实验。依据导航基本原理提出了地面模拟系统的总体构架以及各部分的主要研究内容，设计了单模拟器（依次模拟多脉冲星源）单探测器和多模拟器（分别模拟不同的脉冲星源）多探测器两种地面模拟方案。全文围绕地面模拟系统中X射线脉冲星信号模拟源和X射线探测器两大关键技术进行研究，搭建了单模拟器单探测器的实验系统并对系统性能的影响因素进行了测试分析。针对X射线脉冲星信号模拟源的设计要求，通过分析比较X射线的产生、调制机理和各种方法的优缺点，提出了栅控X射线管调制的方案。详细描述了栅控X射线管的基本结构和产生调制脉冲X射线的工作机理，对栅控X射线管的结构进行设计，计算了栅极电压对电子的控制能力和到达阳极的电子数，研制了栅极控制的X射线管，实验测试了不同阳极电压情况下的出射X射线剂量率、阳极电流和计数率随栅极电压的变化曲线，验证了设计计算的正确性，并以此作为脉冲星信号模拟源信号加载的依据。采用直接数字频率合成的方法研制了任意信号脉冲发生装置，对研制的电子学信号发生器进行测试，结果表明该装置可以根据给定的数据产生任意脉冲轮廓。分析了未来空间应用时对大面积X射线探测器的需求，设计了拼接微通道板MCP（Micro-Channel Plate）探测器的初步方案，提出了共享阳极的方法以减少阵列探测器读出电子学通道数。研制了封装MCP探测器以进行地面模拟实验，测试了该探测器阳极输出原始信号脉冲FWHM约600ps，具有很好的时间响应特性。基于所研制的X射线脉冲星信号模拟源和封装MCP探测器，搭建了单模拟源单探测器的地面模拟实验系统，成功实现了X射线脉冲星信号的模拟。测试并分析了探测器读出电子学阈值电压、入射X射线功率、不同的模拟源栅极信号加载方式、栅控X射线管阳极电压、栅极电压等对模拟系统和采集脉冲轮廓的影响。探测器读出电子学应调整合适的阈值电压，以剔除探测器暗计数和电子学噪声并尽量不影响探测器对有效信号的计数，在本系统中阈值电压为-150mV时脉冲轮廓信噪比较高。X射线强度对累积脉冲轮廓信噪比影响较大，X射线强度与X射线管灯丝电流、栅极控制信号的电压范围和阳极电压相关，灯丝电流越大，出射X射线功率越大，采集到的光子数越多，轮廓越光滑；栅极电压跨度取2V较为合适，栅极电压跨度越大出射X射线强度差越明显，因而脉冲轮廓特征越明显；随着阳极电压的提高，累积的光子数量增多，轮廓越来越光滑。当采用数字信号加载时，频率过低会导致累积脉冲轮廓展宽，分辨精度不够且细节表现差。当数字信号频率高于1MHz时累积脉冲轮廓真实度较好，模拟源产生的信号能够逼真反应实际脉冲星的辐射脉冲轮廓特征。更多还原

【Abstract】 With the development of satellite navigation technology and the increasinglyurgent requirements for autonomous navigation in recent years, the major spacepowers carried out extensive research in the field of X-ray pulsar based navigation.The feasibility of this new navigation method has been recognized by the internationalnavigation experts. On the basis of investigation and analysis of the international anddomestic research progress, scheme and key technologies of the pulsar navigationground simulation system is mainly studied in this thesis.Prior to the space flight test and the application of the X-ray pulsar navigation, aground simulation system needs to be set up in order to study the key technologies ofthe pulsar navigation. All the flight test experiments need to be tested and studied withground simulation system, including the X-ray photon detection, photon arrival timemeasurement, the pulse profile construction and the positioning accuracydetermination. Based on the principle of pulsar navigation, the overall framework ofthe ground simulation system is proposed in the thesis, and the major researchcontents of each part are introduced. Two different simulation schemes are provided,single emulator with single detector and multi-emulator with multi-detector. Keytechnologies of the X-ray pulsar emulator and X-ray detector are studied in detail, andsingle emulator with single detector ground simulation system is built in laboratory toanalyze the system performance.By comparing the advantages and disadvantages of various X-ray generation andmodulation mechanism and methods, a novel grid controlled X-ray tube modulationmethod is proposed according to the requirements of the X-ray pulsar emulator. Thetube structure and modulation mechanism of the grid controlled X-ray tube isillustrated in detail, and the electrode structure and voltage applied on the electrodesare designed and optimized. Quantity of the electrons at the anode, the electron flight trajectory and the grid cut-off voltage of two types of grid are calculated underdifferent anode voltage. The two grid type tubes are designed and fabricated; testresults of X-ray intensity, anode current and the detector count rate coincide with thecalculation results. The relationship of the X-ray intensity and the grid voltage is thepulsar emulation basis. Arbitrary waveform generator is designed and developed withdirect digital Synthesis method.According to pulsar radiation property and navigation space applicationrequirements, large area detector is needed in the future. A Micro-Channel Plate(MCP)tiling detector is suggested, and in order to simplify the electric readout circuit a novelsharing anode method is proposed. Since the large area detector is not suitable for theground simulation because of its size and cost, a compact vacuum sealed MCPdetector for the ground simulation system is developed. The anode output FWHM ofthe sealed detector is600ps.With the developed pulsar emulator and the sealed MCP detector, the singleemulator with single detector pulsar navigation ground simulation system is set up inlaboratory. Different X-ray pulsar pulses are generated and tested, the pulse profilesare reconstructed. The influence of the detector electronics threshold voltage, incidentX-ray intensity, the tube grid signal modulation type, grid voltage and anode voltageare analyzed. In this system all these parameters should be set properly in order to geta high quality pulse profile.更多还原