The effect and properties of drifts in the heliosphere
The effect and properties of drifts in the heliosphere
复制标题
日光层漂移的影响和特性
DOI：
10.1051/0004-6361/202140406
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发表时间：
2021
影响因子：
6.5
通讯作者：
Ferreira
中科院分区：
文献类型：
--
作者：
Ferreira
我们研究了漂移的性质及其对日球层宇宙射线调制的影响，采用了基于帕克输运方程导出的一组随机微分方程解的数值调制模型。利用数值模型的说明能力来更好地理解所涉及的物理调制过程。各种研究表明，漂移需要缩小到太阳活动极大期，本研究着眼于如何实现这一目标。通过将漂移系数乘以一个小于1的因子，可以直接减小漂移，也可以通过漂移-扩散关系间接减小漂移，即通过改变扩散系数，通过改变粒子强度梯度引起漂移效果的变化。给出了两种情况下粒子出口位置和出口能量的等值线图，并说明了模型中的漂移导致更大的能量损失。在调制过程中，伪粒子在日球层不同区域所花费的时间的相对量的数字可以解释这一点。这些数字还表明，扩散的增加导致漂移效应的抑制或减少。最后，图还表明，漂移效应随着粒子能量的增加而减小；尽管漂移系数随着粒子能量的增加而增加，但考虑到与更大能量相关的扩散增加的贡献，总漂移效应导致漂移效应随着能量的增加而减小。
We investigate the properties of drifts and their effect on cosmic ray modulation in the heliosphere using a numerical modulation model based on the solution of a set of stochastic differential equations that was derived from the Parker transport equation. The illustrative capabilities of the numerical model are exploited to yield a better understanding of the physical modulation processes involved. Various studies have indicated that drifts need to be scaled down towards solar maximum conditions and the present study looks at how this can be achieved. Drifts are scaled down directly by multiplying the drift coefficient by a factor of less than unity as well as indirectly through the drift–diffusion relation, that is, by modifying the diffusion coefficient so as to cause a change in the drift effects through altered gradients in particle intensity. Contour plots of particle exit positions and exit energies are presented for both of these cases, and it is illustrated that drifts in the model lead to larger energy losses. This is explained with the aid of figures indicating the relative amount of time spent by pseudo-particles in different regions of the heliosphere during the modulation process. These figures also indicate that an increase in diffusion leads to a suppression or reduction of drift effects. Finally, the figures also show that drift effects are reduced as a function of increasing particle energy; even though the drift coefficient increases with particle energy, the total drift effect, taking into account the contribution from the increased diffusion associated with larger energies, causes drift effects to be reduced with an increase in energy.
外日光层物理学
DOI：
--
发表时间：
1991
期刊：
影响因子：
--
作者：
P. Gazis
通讯作者：
P. Gazis