论文标题
\ emph {parker solar Probe}观察到的折返和非转换间隔的湍流特征
Turbulence characteristics of switchbacks and non-switchbacks intervals observed by \emph{Parker Solar Probe}
论文作者
论文摘要
我们使用\ emph {parker solar Probe}(\ emph {psp})内测量值在第一次太阳能相遇期间分析太阳风湍流的特征,覆盖了$ 35.7R_ \ odot $和$ 41.7r_ \ odot $。在我们的分析中,我们将所谓的换回(SB)间隔(折叠磁场线)与非转换(NSB)间隔隔离,该间隔主要遵循Parker螺旋场。使用基于条件相关函数的技术,我们在SB和NSB间隔中分别估算Elsasser,磁性和散装速度场的功率谱。在比较两种间隔的湍流能谱时,我们找到了以下特征:1)在NSB间隔中向后传播的Elsasser Field $ z^ - $比SB间隔中的一个间隔更大; 2)SB间隔中的磁功率谱比在NSB间隔内具有接近-5/3的频谱指数,其光谱指数接近-3/2; 3)SB和NSB的湍流都与NSB具有最大的交叉疗效的不平衡,4)剩余能量在SB的间隔中大于NSB,而5)5)分析的波动以alfvénic的波动为主导,这些波动在\ emph {sunhard semb {suns pundiess s anti pundies中均在\ emph {\ emph的情况下传播。湍流。这些观察到的特征提供了进一步的证据,表明\ emph {psp}观察到的折返与折叠磁场线相关联,从而洞悉其湍流性质。
We use \emph{Parker Solar Probe} (\emph{PSP}) in-situ measurements to analyze the characteristics of solar wind turbulence during the first solar encounter covering radial distances between $35.7R_\odot$ and $41.7R_\odot$. In our analysis we isolate so-called switchback (SB) intervals (folded magnetic field lines) from non-switchback (NSB) intervals, which mainly follow the Parker spiral field. Using a technique based on conditioned correlation functions, we estimate the power spectra of Elsasser, magnetic and bulk velocity fields separately in the SB and NSB intervals. In comparing the turbulent energy spectra of the two types of intervals, we find the following characteristics: 1) The decorrelation length of the backward-propagating Elsasser field $z^-$ is larger in the NSB intervals than the one in the SB intervals; 2) the magnetic power spectrum in SB intervals is steeper, with spectral index close to -5/3, than in NSB intervals, which have a spectral index close to -3/2; 3) both SB and NSB turbulence are imbalanced with NSB having the largest cross-helicity, 4) the residual energy is larger in the SB intervals than in NSB, and 5) the analyzed fluctuations are dominated by Alfvénic fluctuations that are propagating in the \emph{sunward} (\emph{anti-sunward}) direction for the SB (NSB) turbulence. These observed features provide further evidence that the switchbacks observed by \emph{PSP} are associated with folded magnetic field lines giving insight into their turbulence nature.