  Using the Parker Solar Probe data taken in the inner heliosphere, we
investigate the power and spatial anisotropy of magnetic-field spectra at
kinetic scales (i.e., around sub-ion scales) in solar wind turbulence in the
inner heliosphere. We find that strong anisotropy of magnetic spectra occurs at
kinetic scales with the strongest power in the perpendicular direction with
respect to the local magnetic field (forming an angle theta_B with the mean
flow velocity). The spectral index of magnetic spectra varies from -3.2 to -5.8
when the angle theta_B changes from 90 to 180 (or 0) deg, indicating that
strong anisotropy of the spectral indices occurs at kinetic scales in the solar
wind turbulence. Using a diagnosis based on the magnetic helicity, we show that
the anisotropy of the spectral indices can be explained by the nature of the
plasma modes that carry the cascade at kinetic scales. We discuss our findings
in light of existing theories and current development in the field.
