  I suggest that the main process that amplifies magnetic fields in cooling
flows in clusters and group of galaxies is a jet-driven dynamo (JEDD). The main
processes that are behind the JEDD is the turbulence that is formed by the many
vortices formed in the inflation processes of bubbles, and the large scale
shear formed by the propagating jet. It is sufficient that a strong turbulence
exits in the vicinity of the jets and bubbles, just where the shear is large.
The typical amplification time of magnetic fields by the JEDD near the jets and
bubbles is approximately hundred million years. The amplification time in the
entire cooling flow region is somewhat longer. The vortices that create the
turbulence are those that also transfer energy from the jets to the
intra-cluster medium, by mixing shocked jet gas with the intra-cluster medium
gas, and by exciting sound waves. The JEDD model adds magnetic fields to the
cyclical behavior of energy and mass in the jet-feedback mechanism (JFM) in
cooling flows.
