近地卫星长期SEU事件退火分析

针对近地卫星在轨运行中的单粒子翻转事件(Single Event Upset,SEU)的退火问题,选取某卫星器件长期积累的SEU数据为样本,在分析器件长期温度变化的基础上,详细统计SEU事件的星下点以及年、月等时空分布特征,并讨论SEU事件与地球磁场分布、F10.7曲线、中子监测数据的关联特性,最后以SEU事件发生的平均间隔为目标,建立退火模型,用实际数据进行退火估计。结果表明,SEU事件星下点发生在南大西洋异常区的达到67%以上,发生在南、北两极高纬度区域的超过16%,其它区域的不足17%;8、9、10、12这4个月份的SEU事件最多,占全年的38%以上;以远、近日点为参考时,发生在4～9月的约占50%,发生在其它月份的也在50%附近,两者十分接近;长期SEU事件受宇宙射线、太阳活动影响明显,长期性变化以宇宙射线影响为主,短期性变化以太阳活动影响为主;在轨道周期内温度变化约2℃、长期温升接近5℃的条件下,SEU事件时间间隔的均值约4.57d,退火零值约1.56×10-13 d,退火因子约7.94×10-15 d-1,衰减零值约24.34d,衰减因子约0.12d-1,退火特征并不明显,退火影响可不用考虑。

Annealing analysis to long term SEUs for LEO satellite

With respect to annealing effect to single event upset(SEU), a single device from a LEO (Low Earth Orbit) satellite running on sun synchronous orbit more than 9 years is selected as a sample. Working temperature from satellite telemetry data is investigated and details on SEU nadir and time are discussed, and related to geomagnetic field, F10.7, and neutrons monitoring data and so on. Based on averaging SEU time intervals, a model is developed to estimate annealing characteristics and is examined with the telemetry data. Results illustrate that the SEU nadir has happened above the South Atlantic Abnormal(SAA) area more than 67%, and the polar area and the other area, greater than 16% and less than 17%, respectively; and the SEUs has the most probability above 38% in August, September, October and December, but the probability is extremely equal when one month group is from April to September and the other group contains the remaining months; and the SEU frequency is influenced by the cosmic rays in long term when the Sun is relatively quiet and by the Sun in short term when the Sun is relatively active. The annealing estimation shows that the mean time interval between SEUs is about 4.57d, and the annealing zero value is close to 1.56×10-13d with the annealing factor of 7.94×10-15d-1, and the degradation zero value is nearly 24.34d with the factor of 0.12d-1. From the estimation, the annealing effect is approximately negligible.