论文标题
生长或衰减 - I：湍流发电机饱和的普遍性
Growth or Decay -- I: universality of the turbulent dynamo saturation
论文作者
论文摘要
湍流的小规模发电机（SSD）可能是我们今天在宇宙中观察到的星际介质（ISM）的磁性的原因。 The SSD efficiently converts kinetic energy $E_{\rm kin}$ into magnetic energy $E_{\rm mag} $, and is often used to explain how an initially weak magnetic field with $E_{\rm mag} \ll E_{\rm kin}$ is amplified, and then maintained at a level $E_{\rm mag} \ Lessim E _ {\ rm kin} $。通常，通过初始化弱种子磁场并让湍流生长到饱和度来研究此过程。但是，在这一生长或衰减系列的第一部分中，使用三维，抗Visco的磁性水动力动力学湍流模拟，直至2000年的磁性雷诺数，我们表明，如果最初也可以实现磁场的整体数量，能量光谱和特征性范围的相同最终状态，即甚至最初是$ e _ {\ rm mag} \ gg e _ {\ rm kin} $。这表明湍流发电机的最终饱和状态是由血浆的湍流和材料特性设置的，与磁场的初始结构或振幅无关。我们讨论了这对湍流等离子体中磁场和未来研究的磁场的影响，以探索发电机饱和。
The turbulent small-scale dynamo (SSD) is likely to be responsible for the magnetisation of the interstellar medium (ISM) that we observe in the Universe today. The SSD efficiently converts kinetic energy $E_{\rm kin}$ into magnetic energy $E_{\rm mag} $, and is often used to explain how an initially weak magnetic field with $E_{\rm mag} \ll E_{\rm kin}$ is amplified, and then maintained at a level $E_{\rm mag} \lesssim E_{\rm kin}$. Usually, this process is studied by initialising a weak seed magnetic field and letting the turbulence grow it to saturation. However, in this Part I of the Growth or Decay series, using three-dimensional, visco-resistive magnetohydrodynamical turbulence simulations up to magnetic Reynolds numbers of 2000, we show that the same final state in the integral quantities, energy spectra, and characteristic scales of the magnetic field can also be achieved if initially $E_{\rm mag} \sim E_{\rm kin}$ or even if initially $E_{\rm mag} \gg E_{\rm kin}$. This suggests that the final saturated state of the turbulent dynamo is set by the turbulence and the material properties of the plasma, independent of the initial structure or amplitude of the magnetic field. We discuss the implications this has for the maintenance of magnetic fields in turbulent plasmas and future studies exploring the dynamo saturation.
