南大西洋地磁异常区的辐射环境与低轨卫星粒子辐射通量计算

利用国际地磁参考场模型ＩＧＲＦ９０,分析了南大西洋异常（ＳＡＡ）区磁场变化的特征,计算了低轨卫星轨道积分粒子辐射通量及其随年代的变化。结果表明,在ＳＡＡ上空,同一高度上的磁场随时间的推移而减弱,粒子辐射通量随时间的推移而增加．对不同高度的卫星,轨道积分粒子辐射通量随年代的变化相差很大,低轨（＜１０００ｋｍ）卫星的变化明显,而＞１０００ｋｍ时变化很小．粒子辐射通量随时间变化的主要原因是ＳＡＡ区的磁壳结构畸变和“移动”,因此,计算不同年代的轨道粒子辐射通量,应使用同年代的磁场模型。近期卫星测量结果表明,这一论断与观测相符。本文提供的计算轨道积分粒子通量方法,结果的可靠性较高,对卫星的合理设计,载人飞船的辐射防护以及卫星的正常运行都有重要参考价值。

THE RADIATION ENVIRONMENT WITHIN THE SOUTH ATLANTIC ANOMALY REGION AND THE CALCULATING TRAPPED PARTICLES FLUXES FOR LOW ORBITAL SATELLITE

The secular magnetic field variation in the south Atlantic anomaly (SAA) regionis studied by using the international geomagnetic reference field (1990s) model.Integral trapped particles fluxes along low altitude orbits and their secular variation arecalculated with AP8/AE8 models. It is shown that below 1000 km at a fixed altitudeabove the SAA, the strength of magnetic field and trapped particles fluxes aredecreased and increased with increasing time, respectively, while higher than 1000kmno noticeable variation are found. We think that the reason responsible for the secularvariation of particles fluxes is the distortion and "movement" of the drift shell. It issuggested that when calculating trapped particles fluxes at lower altitudes, one shoulduse the contemporary IGRF model. Satellite observations made in the mid late 1980sseen to be consistent with the viewpoint of the present work.