Université Paris-Sud, Institut d'Astrophysique Spatiale, UMR 8617, Bâtiment 121, F-91405 Orsay, France.
Phys Rev Lett. 2012 Nov 9;109(19):194501. doi: 10.1103/PhysRevLett.109.194501. Epub 2012 Nov 7.
Hall magnetohydrodynamics (MHD) is investigated through three-dimensional direct numerical simulations. We show that the Hall effect induces a spontaneous chiral symmetry breaking of the turbulent dynamics. The normalized magnetic polarization is introduced to separate the right- (R) and left-handed (L) fluctuations. A classical k(-7/3) spectrum is found at small scales for R magnetic fluctuations which corresponds to the electron MHD prediction. A spectrum compatible with k(-11/3) is obtained at large-scales for the L magnetic fluctuations; we call this regime the ion MHD. These results are explained heuristically by rewriting the Hall MHD equations in a succinct vortex dynamical form. Applications to solar wind turbulence are discussed.
通过三维直接数值模拟研究了磁场中的磁流体动力学(MHD)。结果表明,霍尔效应会导致湍流动力学自发破缺手征对称性。引入归一化磁极化来分离右旋(R)和左旋(L)涨落。在小尺度上,R 磁涨落呈现出经典的 k^(-7/3)谱,与电子 MHD 的预测相符。而在大尺度上,L 磁涨落呈现出与 k^(-11/3)谱兼容的谱,我们称之为离子 MHD。通过简洁的涡动力学形式重写霍尔 MHD 方程,我们对这些结果进行了启发式解释。最后还讨论了这些结果在太阳风湍流中的应用。