Outer helioshpere: a first attempt of magnetic field spectra determination from Voyagers data

The Voyager spacecrafts (V1-V2) are providing unique measurements of plasma and magnetic field at the helioshpere edge. We compare the magnetic field measured from the Voyagers inside the heliosheath (HS) (V1 years 2004-2012, V2 year 2007-). Observations of high variations of energetic particle fluxes at V2, recently suggested the existence of two regions with distinct magnetic field features: the SHS (sectored heliosheath), where the magnetic field alternates the polarity due to the current sheet flapping and piling up as the heliopause is approached, and the UHS (unipolar heliosheath) which extends outside the SHS, where the magnetic field polarity is constant. We present here the first magnetic field power spectra computation inside the heliosheath. The spectra differ in both anisotropy and inertial decay rate. The difference cannot be explained in terms of the different physics supposedly present in the sectored and unipolar regions.