This Letter presents a calculation of the power spectra of weakly turbulent Alfvén waves and fast magnetosonic waves (“fast waves”) in low-$\beta$ plasmas. It is shown that three-wave interactions transfer energy to high-frequency fast waves and, to a lesser extent, high-frequency Alfvén waves. High-frequency waves produced by MHD turbulence are a promising explanation for the anisotropic heating of minor ions in the solar corona.

• Received 21 October 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.265004