| Single event effects(SEEs)induced by space radiation is one of the most important causes of spacecraft failure.In recent years,the harm of SEEs has drawn increasingly attention throughout the world.The development of modern technology requires spacecraft to adopt radiation hardened electronic components.To test the radiation resistance of the electronic components,the ground-based simulation test of SEEs is introduced.The ion fluence is one of the most important parameters in the simulation test.The accuracy of fluence detection directly affects the reliability of test result for the electronic components.In addition,the natural space is a flux variable environment,and the test standards have not set the specific value of ion flux to be used in the simulation test.To address this issue,the effect of ion flux on SEEs was studied and new method for ion fluence detection was explored.It aimed at solving the shortage of relevant supporting data for the flux effect and providing guidance and reference for technical specifications of the ground-based simulation test.In this paper,the experiment concerning flux impact on SEEs has been conducted at the Heavy Ion Research Facility in Lanzhou(HIRFL)using three types of ions Ni,Kr and Bi,covering LET from 10.1 to 99.8 MeV?cm~2/mg.Various types of devices including hardened and unhardened ones have been tested by changing the ion flux from 10 to 10~5 ions/cm~2?s.The impact of various beam parameters on flux effect has been studied,such as ion flux range,LET of the incident ion,and tilted angle of the incident ion,etc.The impact of flux effect on current models used in predicting on-orbit error rate in low flux level was explored.The theoretical mechanism of the flux effect was studied by employing GEANT4 and TCAD simulation method.Radial charge distribution deposited by various ions used in the ground-based experiment was explored.The transient aspect of the ion track structure in silicon devices,together with analysis of the specific device response,was investigated to explain the flux impact on SEEs in different devices.The main results obtained are as follows:1)Effect of flux levelThe experiment results of all the tested devices show flux dependence.At the low flux range(below 10~3 ions/(cm~2?s)),the change of test result is not obvious.While the flux increases above 10~3 ions/(cm~2?s),the effect of flux on SEEs becomes evident,i.e.for most cases the cross section of the single event errors increases.By the analysis of the theoretical simulation result,it can be deduced that the flux effect stems from the associated functioning induced by two or more ions.Only when the ion flux is large enough,the probability of the correlation between two or more ions begins to increase,and the effect of ion flux on SEEs starts to occur.2)Impact of the device structureDifferent device structures show different flux sensitivity.In general,the single event cross section of the hardened device is far lower than the unhardened ones.However,with the increase of the ion flux,the increment of the single event cross section of the hardened device is larger than that of the unhardened ones.For bulk-Si SRAM,the composition of the multi-bit upset is changed with the increase of ion flux,and the upset of more than 3 bit becomes higher.The mechanism analysis of the single event errors at high flux in different structural devices also proves that the flux effect on SEEs results from the correlation of two or more ions.3)Impact of the LETThe LET value of incident ion also has a significant impact on the flux sensitivity for SEEs.The experiment results show that when the LET of incident ion increases,the sensitivity of the flux effect also increases.The ions used in the experiment were simulated by GEANT4 software,and the radial charge distributions of the incident ions were obtained.With the increase of ion LET,the radial charge distribution is wider and the charge density is greater,which makes the probability of correlation of two or more ions increase,and the effect of flux impact becomes more significant.New method for ion fluence detection was explored using the micro channel plate(MCP)detector,which has the advantages of fast time response,large electronic gain and small detection noise.The fabrication method of the MCP ion fluence detector was studied.The influence of different structures on the performance of the detector was analyzed.The performance of the fabricated MCP fluence detector was tested.The signal amplitude of the detector is 250 mV and the signal width is 25 ns.The output signal satisfies the detector design requirements,and it can work at 1 MHz counting rate.In the meantime,the detector's performance was theoretically analyzed,and the detection mechanism of the detector was explored.For the ground-based simulation test,it provides the establishment for the necessary experimental data,basic detection method and relative technology advancement. |
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