Spectrum of Weak Magnetohydrodynamic Turbulence

Turbulence of magnetohydrodynamic waves in nature and in the laboratory is generally cross-helical or nonbalanced, in that the energies of Alfveacuten 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 Alfveacuten 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 to)(-2). The generation of a condensate is apparently related to the breakdown of mirror symmetry in nonbalanced turbulence.