Title: Poynting's theorem in magnetic turbulence,
Abstract: Poynting's theorem is used to obtain an expression for the turbulent
power-spectral density as function of frequency and wavenumber in low-frequency
magnetic turbulence. No reference is made to Elsasser variables as is usually
done in magnetohydrodynamic turbulence mixing mechanical and electromagnetic
turbulence. We rather stay with an implicit form of the mechanical part of
turbulence as suggested by electromagnetic theory in arbitrary media. All of
mechanics and flows is included into a turbulent response function which by
appropriate observations can be determined from knowledge of the turbulent
fluctuation spectra. This approach is not guided by the wish of developing a
complete theory of turbulence. It aims on the identification of the response
function from observations as input into a theory which afterwards attempts its
interpretation. Combination of both the magnetic and electric power spectral
densities leads to a representation of the turbulent response function, i.e.
the turbulent conductivity spectrum $\sigma_{\omega k}$ as function of
frequency $\omega$ and wavenumber $k$. {It is given as the ratio of magnetic to
electric power spectral densities in frequency space. This knowledge allows for
formally writing down a turbulent dispersion relation. Power law inertial range
spectra result in a power law turbulent conductivity spectrum. These can be
compared with observations in the solar wind. Keywords: MHD turbulence,
turbulent dispersion relation, turbulent response function, solar wind
turbulence