Abstract—The propagation of solar cosmic rays (SCR) in the interplanetary medium is considered on the basis of the Fokker–Planck kinetic equation. It is known that the SCR distribution function averaged over a solar proton event contains valuable data on the scattering process for energetic charged particles by interplanetary magnetic fields. A steady-state solution for the kinetic equation in the small-angle approximation is obtained, and the dependence of the angular distribution function of cosmic rays on the distance to the particle source is examined. This solution is applicable if the distance to the particle source is short compared to the mean free path of cosmic rays and if particles are moving primarily in the radial direction. The angular distribution of particles at large (compared to the mean free path of cosmic rays) distances to the particle source is also analyzed. An analytical expression for the distribution function of cosmic rays in the form of a sum of an isotropic component and a small anisotropic one is derived. It is demonstrated that the angular distribution of cosmic rays depends to a considerable extent on the anisotropy of their scattering. The scattering characteristics of energetic charged particles by fluctuations of interplanetary magnetic fields are estimated based on observational data for several SCR flares.

中文翻译：

---

长时间粒子注入下太阳宇宙射线的分布函数

摘要-根据Fokker-Planck动力学方程考虑了太阳宇宙射线（SCR）在行星际介质中的传播。已知在太阳质子事件上平均的SCR分布函数包含有关行星际磁场对高能带电粒子的散射过程的有价值的数据。在小角近似中获得了动力学方程的稳态解，并研究了宇宙射线的角分布函数对与粒子源的距离的依赖性。如果到粒子源的距离比宇宙射线的平均自由程短，并且粒子主要在径向上移动，则适用此解决方案。还分析了到粒子源的较大距离（与宇宙射线的平均自由程相比）处的粒子角度分布。推导了以各向同性分量和小的各向异性分量之和形式表示的宇宙射线分布函数的解析表达式。结果表明，宇宙射线的角度分布在很大程度上取决于其散射的各向异性。基于几个SCR耀斑的观测数据，估计了行星际磁场波动引起的高能带电粒子的散射特性。结果表明，宇宙射线的角度分布在很大程度上取决于其散射的各向异性。基于几个SCR耀斑的观测数据，估计了行星际磁场波动引起的高能带电粒子的散射特性。结果表明，宇宙射线的角度分布在很大程度上取决于其散射的各向异性。基于几个SCR耀斑的观测数据，估计了行星际磁场波动引起的高能带电粒子的散射特性。