| As the development of astronautical technology, the human exploratory urge fordeep space is more and more seriously. But, with the distance of the spacecraft flewout of the earth’s is farther and farther away, satellite navigation system which usedfor spacecraft navigation cannot satisfy our needs, and it presents more and morelimitations in certain function. In order to break this situation, in recent years, eachspacefaring nations invested a lot of manpower, material resources for the nextgeneration navigation system—X-ray pulsar navigation system. On the basis of theinvestigation research progress at home and abroad, the future space applicationsdemand for large area X-ray detector is analyzed, so this paper mainly studies thespace X-ray detector used for navigation.For researching the key technologies about the X ray detector, the groundexperiment system must be set up before putting the detector into a real outer spaceenvironment and applying in navigation system in the future. It is mainly used fortesting and calibrating the detectors presicely and comprehensively, such as thedetection efficiency, the accumulation of photon arrival time, pulse profile,positioning precision of the calculation and orbit control and other related researchand experiment on the ground.Prior to calibrate the detector, we need a X-ray source which can emits differentenergies, and the photon flux has been measured. According to the demands ofexperiment for detector test, X-ray source was developed. A breif introduction aboutworking principle, function and characteristics are given. X source can emit photonswith seven different kinds of energy, respectively are1.49keV,4.51keV,5.41keV,6.4keV,8.05keV,15.77keV,17.48keV. Stability of the photon flux andmonochromaticity of spectroscopy are measured by taking use of the XR-100SDD-Xray detector. By changing the filament current If, anode voltage Va and distancebetwween the X ray source and the detector L, X-ray photon flux was tested witheach energy.On the basis of the pulsar periodic radiation characteristic and the demand of theX-ray pulsar navigation, full text around the research of the development of thedetector used for detecting weak X-ray signals. The cesium iodide photocathode’s physics model、structure (reflection types and transmission type) and film thickness(transmission layer thickness, the thickness of the reflection) are reviewed. Analysisabout the factors that influence quantum efficiency is made, such as the way ofevaporation in the coating process, vacuum degree, the deposition rate, the surfacemass density, annealing process after coating.Compound photoelectronic cathode structure is designed for improving thedetection efficiency of the detector.Two parameters are determined by analog computation with CST software: Oneis potential difference between filter and input MCP, the best value is-300V; the otheone is anode voltage, for improving the anode’s collection efficiency, anode voltageof the detector was optimized. Anode voltage mainly influence the electron beam’sradius. With the increasing of anode voltage, the radius of electron beam becomingmuch smaller, until it reached to the minnum value. So the diameter of a electronbeam, emitted from a micro channel, under the diferent anode voltages, is simulated，the results show that when the anode voltage at–450V, the radius of the electronbeam can be compressed from0.9mm to0.6mm, and the electronic beam radiuschanged little if the the voltage are increased continuously. Experimental results showthat when the anode voltage at–450V, the detection efficiency is the highest.In order to obtain the optimal thickness of transmission layer cesium iodide ofcompound photocathode, two calculation methods is utilized. According to thetheoretical values, the transimission lay’s quantum effiency and detection effiency aresimulated by GEANT4, simulation results show that: the second algorithm is superiorto the first one. For the purpose of guaranteeing the reliability of the aboveconclusion, under the same conditions, the quantum efficiency and detectionefficiency of transmission layer with different thickness is figured, the results showthat: optimal values derived from the second calculation method is reliable. Detectionefficiency of pure reflected photocathode and compound photocathode are tested,Under the same experimental conditions, test results show that the efficiency of thecompound photocathode is respectively are25.253%@1.49keV and14.277%@4.51keV，it agrees with the expection conclusion.According to the basic principle，principle prototype of the array（2×2）X-raydetector is designed. Suitable material for each part of the detector is selected,especially the main part. The calculation of static mechanics of main part with different materials is carried on(mainly about the distribution laws of stress anddisplacement). Test solution for the array detector applied in the future is made.A method of screening MCP with consistent performance is put forward，itmainly includes the following steps: establishing available four key parameters,building available standard, optimizing the experiment process and experimentalmeasurement.Multi-channel shared anode is developed, so the channels of electronicsacquisition system used for MCP array detector can be reduced, then the volume,power consumption, and weight of the whole detection system are reducedeffectively.Signal transmission performance of single channel anode, double-channel sharedanode, and four-channel shared anode is simulated, the simulation results showed that:when the frequency of gaussian pulse signal less than0.1GHz, three kinds of anodecan propagate the signal without waveform distortion, amplitude fading, pulsebroadening, and the simulation results are agree with the experimental results whichare obtained by observing the oscilloscope. |
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