论文标题
太阳光谱波导中的缓慢表面扭结模式的阻尼由一维不均匀性建模
Damping of slow surface kink modes in solar photospheric waveguides modeled by one-dimensional inhomogeneities
论文作者
论文摘要
鉴于最近对毛孔和黑子伞的磁水动力学(MHD)波的兴趣,我们通过对慢性表面扭结模式(SSKM)的阻尼进行了对太阳光传导的建模,该模型用圆柱体的圆柱质量引导,构成圆柱体吸入性的无 /均匀内部的均匀内部和均匀内部和持续过渡(t snementior niber)的过渡(t interiention sive)。在线性,电阻,无重力MHD中进行本元模式分析,我们的方法是理想化的,因为除其他外,我们的平衡仅在径向方向上构成。尽管如此,我们仍可以同时解决两种阻尼机制,一个是欧姆电阻率,另一个是尖skms和alfv $ \急性{\ rm e} $ n Continua中SSKM的共振吸收。我们发现两种机制的相对重要性取决于磁性雷诺数($ r _ {\ rm m} $)。谐振吸收是$ r _ {\ rm m} $的现实较大值的唯一阻尼机制,并且总体上,cusp共振主导了Alfv $ \ acute \ at急性{\ rm e} $ n,除非轴向axial vavenumbers在较低的相关范围内。我们还发现,仅当tl宽度 - 拉迪乌斯比率远小于名义预期的时,薄支台近似只有。对于现实的小$ r _ {\ rm m} $,欧姆电阻率更为重要。即使在这种情况下,SSKM也只会略微降低,在我们检查的参数范围内,阻尼时间到周期性ratios达到$ \ sim 10 $。
Given the recent interest in magnetohydrodynamic (MHD) waves in pores and sunspot umbrae, we examine the damping of slow surface kink modes (SSKMs) by modeling solar photospheric waveguides with a cylindrical inhomogeneity comprising a uniform interior, a uniform exterior, and a continuous transition layer (TL) in between. Performing an eigen-mode analysis in linear, resistive, gravity-free MHD, our approach is idealized in that, among other things, our equilibrium is structured only in the radial direction. We can nonetheless address two damping mechanisms simultaneously, one being the Ohmic resistivity, and the other being the resonant absorption of SSKMs in the cusp and Alfv$\acute{\rm e}$n continua. We find that the relative importance of the two mechanisms depends sensitively on the magnetic Reynolds number ($R_{\rm m}$). Resonant absorption is the sole damping mechanism for realistically large values of $R_{\rm m}$, and the cusp resonance in general dominates the Alfv$\acute{\rm e}$n one unless the axial wavenumbers are at the lower end of the observationally relevant range. We also find that the thin-boundary approximation holds only when the TL-width-to-radius ratios are much smaller than nominally expected. The Ohmic resistivity is far more important for realistically small $R_{\rm m}$. Even in this case, SSKMs are only marginally damped, with damping-time-to-period-ratios reaching $\sim 10$ in the parameter range we examine.