非赤道区域激发的磁声波对辐射带电子的渡越时间散射效应

Transit-time scattering of radiation belt electrons by off-equatorially generated magnetosonic waves

在内磁层中,磁声波被认为能够通过渡越时间散射影响很大能量以及投掷角范围的辐射带电子.近期观测研究发现,磁声波可以在等离子体层内的非赤道区域被激发并且在纬度覆盖范围、法向角变化等方面都与传统的赤道区域磁声波有显著不同.利用之前发展的试验粒子模型,我们研究了非赤道磁声波对辐射带电子的渡越时间散射效应.发现该效应主要发生在波列的边缘.波动纬度覆盖范围的扩展造成了该效应的有效赤道投掷角范围的收缩.相比于赤道区域磁声波,非赤道激发的磁声波可以产生更强的能量扰动以及可忽略的投掷角扰动.

In the inner magnetosphere,the magnetosonic waves have been proposed to transit-time scatter the radiation belt electrons over a broad range of energy and pitch-angle.Recent observations have shown that magnetosonic waves can be generated in the off-equatorial plasmasphere,whose latitudinal coverage and propagation angle are significantly different from the traditional magnetosonic waves confined near the equator.Using our previously-developed test-particle code,we here investigate the possible transit-time scattering of radiation belt electrons by the off-equatorially generated magnetosonic waves.Our results indicate that the transit-time scattering is primarily related to the perturbation near the edge of the finite wave train.The extending of wave occurrence latitudes causes the shrinking of the equatorial pitch-angle range of the transit-time scattering.Compared to the near-equatorially confined magnetosonic waves,the off-equatorially generated magnetosonic waves produce ignorable pitch-angle perturbations but slightly stronger energy perturbations.