Research Of Key Technologies For X-ray Pulsar Simulation And X-ray Detector

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.