论文标题
三维MHD波在冠状空点附近的传播:新波模式分解方法
Three-dimensional MHD wave propagation near a coronal null point: a new wave mode decomposition approach
论文作者
论文摘要
我们提出了一种新的MHD波分解方法,该方法克服了现有波浪识别方法的局限性。我们的方法允许研究太阳气氛不同位置的不同MHD模式中的能量通量,因为涡流流穿过太阳气氛并在磁性空的磁性空中传播。我们通过冠状空配置模拟波动力学,并在我们的底部光谱边界上应用旋转波驱动器。为了确定与不同MHD波模式相关的波能通量,我们采用了一种波分解方法,能够唯一区分不同的MHD模式。我们提出的方法利用3D空间中单个磁场线的几何形状将与三个基本MHD波相关的速度扰动分开。我们的波浪识别方法与以前的基于横向表面的方法一致,并在无效配置的各个位置的波能通量方面给出了预期的结果。我们表明,普遍存在的涡流流激发了MHD波,这对太阳能电晕的po弹通量产生了重大贡献。 Alfvén波能量通量积聚在风扇表面上,快速波能通量在空点附近积累。在脊柱和风扇表面上存在强烈的电流密度。该方法比先前使用的波浪分解方法具有优势,因为每当知道3D Fieldline形状时,它可以用于逼真的模拟或磁性外推,以及实际的太阳能观察结果。零附近与磁性声波相关的能量通量的增强可能对喷射和冲动等离子体流的形成具有重要意义。
We present a new MHD wave decomposition method that overcomes the limitations of existing wave identification methods. Our method allows to investigate the energy fluxes in different MHD modes at different locations of the solar atmosphere as waves generated by vortex flows travel through the solar atmosphere and pass near the magnetic null. We simulate wave dynamics through a coronal null configuration and apply a rotational wave driver at our bottom photospheric boundary. To identify the wave energy fluxes associated with different MHD wave modes, we employ a wave-decomposition method that is able to uniquely distinguish different MHD modes. Our proposed method utilizes the geometry of an individual magnetic field-line in 3D space to separate out velocity perturbations associated with the three fundamental MHD waves. Our method for wave identification is consistent with previous flux-surface-based methods and gives expected results in terms of wave energy fluxes at various locations of the null configuration. We show that ubiquitous vortex flows excite MHD waves that contribute significantly to the Poynting flux in the solar corona. Alfvén wave energy flux accumulates on the fan surface and fast wave energy flux accumulates near the null point. There is a strong current density buildup at the spine and fan surface.The proposed method has advantages over previously utilized wave decomposition methods, since it may be employed in realistic simulations or magnetic extrapolations, as well as in real solar observations, whenever the 3D fieldline shape is known. The enhancement in energy flux associated with magneto-acoustic waves near nulls may have important implications in the formation of jets and impulsive plasma flows.