Generation of magnetic fields in a positive-negative dusty plasma

It is shown that purely growing magnetic fields in a two-component dusty plasma can be generated due to the equilibrium drift of positive and negative dust grains. For this purpose, a linear dispersion relation has been derived by using the hydrodynamic equations for the charged dust fluids, the Maxwell equation and Faradays law. The dispersion relation admits a purely growing instability the growth rate of which is proportional to the equilibrium streaming speeds of positive and negative dust grains. A possible physical explanation for the instability is offered. Applications of our investigation to magnetic fields in the thin Martian environments, interplanetary spaces and dense molecular clouds are mentioned.