标题： 能量和螺旋度演化在通量浮现模拟中 显示英文标题

标题： Energy and helicity evolution in a flux emergence simulation

摘要： 目标。 本工作的主要目的是研究磁极性倒转线（PIL）的相对螺旋度在磁流体动力学模拟中的演化。 方法。 使用的模拟是一个典型的通量浮现模拟，在此模拟中还有一个倾斜的、先前存在的磁场。 浮现场和环境场的相互作用产生了强烈的日冕活动，其中四条喷流尤为突出。 三维磁场使我们能够计算各种能量和螺旋度，并研究它们在模拟期间的演化，特别是在识别的喷流附近。 我们检查了所有量在三个不同区域的演化：在整个体积内，在整个体积的三个独立子体积内，以及在光球上的PIL周围的二维区域内。 结果。 我们发现螺旋度通常对喷流更敏感，其次是自由能。 电流携带螺旋度与相对螺旋度的比值——爆发指数，在其他情况下表现出典型的行为，但在此情况下其变化并不遵循喷流的产生。 通过考虑子体积，我们发现磁场随着高度增加变得更势能，螺旋度减少。 PIL相对螺旋度证实了它在观测到的活跃区域中最近的结果，在喷流期间表现出比标准相对螺旋度更强的变化。 此外，PIL周围的电流携带螺旋度表现出与PIL相对螺旋度类似的行为，因此该量在太阳爆发研究中同样有用。 显示英文摘要

摘要： Aims. The main aim of this work is to study the evolution of the recently introduced relative helicity of the magnetic polarity inversion line (PIL) in a magnetohydrodynamics simulation. Methods. The simulation used is a typical flux emergence simulation in which there is additionally an oblique, pre-existing magnetic field. The interaction of the emerging and ambient fields produces intense coronal activity, with four jets standing out. The 3D magnetic field allows us to compute various energies and helicities, and to study their evolution during the simulation, especially around the identified jets. We examine the evolution of all quantities in three different regions: in the whole volume, in three separate subvolumes of the whole volume, and in a 2D region around the PIL on the photosphere. Results. We find that the helicities are in general more responsive to the jets, followed by the free energy. The eruptivity index, the ratio of the current-carrying helicity to the relative helicity, does not show the typical behaviour it has in other cases, as its variations do not follow the production of the jets. By considering the subvolumes we find that the magnetic field gets more potential and less helical with height. The PIL relative helicity confirms the recent results it showed in observed active regions, exhibiting stronger variations during the jets compared to the standard relative helicity. Moreover, the current-carrying helicity around the PIL has a similar behaviour to the PIL relative helicity, and so this quantity could be equally useful in solar eruptivity studies.