  We determine the magnetic helicity, along with the magnetic energy, at high
latitudes using data from the Ulysses mission. The data set spans the time
period from 1993 to 1996. The basic assumption of the analysis is that the
solar wind is homogeneous. Because the solar wind speed is high, we follow the
approach first pioneered by Matthaeus et al. (1982, Phys. Rev. Lett. 48, 1256)
by which, under the assumption of spatial homogeneity, one can use Fourier
transforms of the magnetic field time series to construct one-dimensional
spectra of the magnetic energy and magnetic helicity under the assumption that
the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied
assumption for the data used in this study. The magnetic helicity derives from
the skew-symmetric terms of the three-dimensional magnetic correlation tensor,
while the symmetric terms of the tensor are used to determine the magnetic
energy spectrum. Our results show a sign change of magnetic helicity at
wavenumber k~2 AU^{-1} (or frequency nu~2 uHz) at distances below 2.8 AU and at
k~30 AU^{-1} (or nu~25 uHz) at larger distances. At small scales the magnetic
helicity is positive at northern heliographic latitudes and negative at
southern latitudes. The positive magnetic helicity at small scales is argued to
be the result of turbulent diffusion reversing the sign relative to what is
seen at small scales at the solar surface. Furthermore, the magnetic helicity
declines toward solar minimum in 1996. The magnetic helicity flux integrated
separately over one hemisphere amounts to about 10^{45} Mx^2/cycle at large
scales and to a 3 times lower value at smaller scales.
