论文标题
惯性alfven湍流中的动态相位对准
Dynamic Phase Alignment in Inertial Alfven Turbulence
论文作者
论文摘要
在具有足够低的电子β的弱倾向的等离子体环境中，Alfvénic湍流在电子皮肤深度以下的尺度上转变为惯性的Alfvénic湍流，$ k_ \ perp d_e \ gtrsim 1 $。我们认为，在惯性的阿尔夫奇尼奇湍流中，能量和广义动力学螺旋性表现出直接的级联反应。我们证明，由于速度和磁场波动之间的相位比对角的存在，两个级联对于$ \cosα_K\ propto k _ {\ perp}^{ - 1} $。动力学和磁能光谱量表分别为$ \ propto k _ {\ perp}^{ - 5/3} $和$ \ propto k _ {\ perp}^{ - 11/3} $。由于双直接级联反应，广义螺旋谱量表为$ \ propto k^{ - 5/3} _ {\ perp} $，这意味着cascade在$ k _ {\ perp} d_e d_e \ gg gg gg gg gg gg gg gg gg gg gg gg gg gg gg gg 1 $范围内进行湍流的渐进平衡。湍流涡流表现出相位空间各向异性$ k _ {\ Parallel} \ propto k _ {\ perp}^{5/3} $，与持差异平衡的惯性alfvén波动一致。我们的结果可能适用于各种地球物理，空间和天体物理环境，包括地球的磁石和电离层，太阳能电晕，非偏见对等离子体以及强烈旋转的非电离流体。
In weakly-collisional plasma environments with sufficiently low electron beta, Alfvénic turbulence transforms into inertial Alfvénic turbulence at scales below the electron skin-depth, $k_\perp d_e\gtrsim 1$. We argue that, in inertial Alfvénic turbulence, both energy and generalized kinetic helicity exhibit direct cascades. We demonstrate that the two cascades are compatible due to the existence of a strong scale-dependence of the phase alignment angle between velocity and magnetic field fluctuations, with the phase alignment angle scaling as $\cosα_k\propto k_{\perp}^{-1}$. The kinetic and magnetic energy spectra scale as $\propto k_{\perp}^{-5/3}$ and $\propto k_{\perp}^{-11/3}$, respectively. As a result of the dual direct cascade, the generalized-helicity spectrum scales as $\propto k^{-5/3}_{\perp}$, implying progressive balancing of the turbulence as the cascade proceeds to smaller scales in the $k_{\perp} d_e \gg 1$ range. Turbulent eddies exhibit a phase-space anisotropy $k_{\parallel} \propto k_{\perp}^{5/3}$, consistent with critically-balanced inertial Alfvén fluctuations. Our results may be applicable to a variety of geophysical, space, and astrophysical environments, including the Earth's magnetosheath and ionosphere, solar corona, non-relativistic pair plasmas, as well as to strongly rotating non-ionized fluids.
