带电粒子在近地球区运动的计算方法

基于磁层粒子动力学理论,根据单粒子方法和偶极磁场模型,在近地球区(L＜10),详细讨论了带电粒子的运动特征以及适合不同能量的带电粒子的计算方法,定量分析了磁层中的电场和磁场对各种能量的带电粒子漂移运动的影响.结果表明,对于能量低于105 eV的电子和102 eV的质子,宜采用引导中心近似方法;对于能量介于105～108 eV之间的电子和102～108 eV之间的质子,可在部分区域内采用引导中心近似方法,若运动区在10 Re内,则只能采用变步长的轨道法;而对于引导中心方法,粒子能量高于105 eV时可以忽略电场漂移的影响,粒子能量低于103 eV时不必考虑磁场漂移的影响,从而简化了引导中心方程组,提高了数值计算效率. 

Calculating Method on Charged Particles Motion in the Near-Earth Region

In this paper, based on the theory of magnetospheric particle dynamics, the charged particles motion character and the calculating method appropriate to these different energy particles in the near-earth region （L 〈 10） are discussed in detail, in terms of the single particle approach and dipole filed model. And then, it is analyzed quantitatively how the electric and magnetic field in the magnetosphere determined these particles drift motion. It is shown that, for the electron and proton with energy lower than 10^5 eV and 10^2 eV, respectively, the Guiding-Center Approximation Appoach （GCAA） is recommended; for 10^5 - 10^8 eV electron and 10^2 - 10^8 eV proton, GCAA or trajectory approach with adaptive step can be adopted in some regions. As for GCAA, the electric drift can be ignored when particle energy is higher than 10^5 eV, and the magnetic drift does not need to be taken into account when particle energy is lower than 10^3 eV. So the guiding-center equations are simplified and the efficiency of numerical calculation is improved.