Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA.
Phys Rev Lett. 2009 Nov 27;103(22):225001. doi: 10.1103/PhysRevLett.103.225001. Epub 2009 Nov 23.
Turbulence of magnetohydrodynamic waves in nature and in the laboratory is generally cross-helical or nonbalanced, in that the energies of Alfvén waves moving in opposite directions along the guide magnetic field are unequal. Based on high-resolution numerical simulations it is proposed that such turbulence spontaneously generates a condensate of the residual energy E(v) - E(b) at small field-parallel wave numbers. As a result, the energy spectra of Alfvén waves are generally not scale invariant in an inertial interval of limited extent. In the limit of an infinite Reynolds number, the universality is asymptotically restored at large wave numbers, and both spectra attain the scaling E(k) proportional to k(perpendicular)(-2). The generation of a condensate is apparently related to the breakdown of mirror symmetry in nonbalanced turbulence.
自然和实验室中的磁流体力学波的湍流通常是交叉螺旋或非平衡的，因为沿着导向磁场反向运动的阿尔芬波的能量是不相等的。基于高分辨率数值模拟，提出这种湍流会自发地在小的场平行波数处产生残余能量 E(v) - E(b)的凝聚体。结果，在有限的惯性区间内，阿尔芬波的能谱通常不是标度不变的。在无穷大雷诺数的极限下，在大的波数处渐近地恢复了普遍性，并且两个谱都达到了 E(k)正比于 k(perpendicular)(-2)的标度律。凝聚体的产生显然与非平衡湍流中镜像对称的破坏有关。
