The magnetic fields of interplanetary coronal mass ejections (ICMEs), which originate close to the Sun in the form of a flux rope, determine their geoeffectiveness. Therefore, robust flux rope‐based models of CMEs are required to perform magnetohydrodynamic (MHD) simulations aimed at space weather predictions. We propose a modified spheromak model and demonstrate its applicability to CME simulations. In this model, such properties of a simulated CME as the poloidal and toroidal magnetic fluxes, and the helicity sign can be controlled with a set of input parameters. We propose a robust technique for introducing CMEs with an appropriate speed into a background, MHD solution describing the solar wind in the inner heliosphere. Through a parametric study, we find that the speed of a CME is much more dependent on its poloidal flux than on the toroidal flux. We also show that the CME speed increases with its total energy, giving us control over its initial speed. We further demonstrate the applicability of this model to simulations of CME‐CME collisions. Finally, we use this model to simulate the 12 July 2012 CME and compare the plasma properties at 1 AU with observations. The predicted CME properties agree reasonably with observational data.

中文翻译：

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改进的Spheromak模型在模拟内部日球冠状物质抛射中的应用

行星际冠状物质抛射（ICME）的磁场以通量绳的形式起源于太阳附近，决定了它们的地球有效性。因此，需要使用鲁棒的基于CME的通量绳模型来执行针对空间天气预报的磁流体动力学（MHD）模拟。我们提出了一种改进的spheromak模型，并证明了其在CME模拟中的适用性。在此模型中，可以使用一组输入参数来控制模拟CME的特性（例如，极磁通和环形磁通）以及螺旋度符号。我们提出了一种健壮的技术，用于以适当的速度将CME引入到背景MHD解决方案中，该解决方案描述了内部日球层中的太阳风。通过参数研究 我们发现，CME的速度更多地取决于其极性通量，而不是环形通量。我们还显示出CME速度随其总能量的增加而增加，从而使我们可以控制其初始速度。我们进一步证明了该模型在CME-CME碰撞模拟中的适用性。最后，我们使用该模型来模拟2012年7月12日的CME，并将1 AU下的等离子体特性与观测值进行比较。预测的CME特性与观测数据合理吻合。