The turbulence surrounding comet Giacobini-Zinner reached intensities three orders of magnitudes above that of ''intermediate'' solar wind conditions, was characterized by Δ B/B0 almost equal to one, and extended to cometocentric distances beyond 106 km. The strong spectral peak at f~10-2 Hz and the general intensity profile of the turbulence (a lack of emissions close to the nucleus [106 km) are in excellent agreement with generation by plasma instabilities associated with the pickup of H2O+ group ions.

The total energy of the magnetic turbulence near f~10-2 Hz is estimated to be ~5¿1015 joules and that of ion energization due to solar wind pickup ~6¿1013 watts. It thus takes a minimum of ~100 s to build up the magnetic turbulence. This scale is approximately the linear growth rate of the ion pickup instability, giving a consistent picture of the energy source of the turbulence.