糖心TV

Abstract: The existence of planetary and stellar magnetic fields is
attributed to the dynamo instability, the mechanism by which a
background turbulent flow spontaneously generates a magnetic field by
the constructive refolding of magnetic field lines. Many efforts have
been made by several experimental groups to reproduce the dynamo
instability in the laboratory using liquid metals. However, so far,
unconstrained dynamos driven by turbulent flows have not been achieved
in the intrinsically low magnetic Prandtl number $P_m$ (i.e. $Pm =
Rm/Re << 1$) laboratory experiments. In this seminar I will demonstrate
that the critical magnetic Reynolds number $Rm_c$ for turbulent dynamos
in the low $P_m$ limit can be significantly reduced if the flow is
submitted to global rotation. Even for moderate rotation rates the
required energy injection rate can be reduced by a factor more than
1000. Our finding thus points into a new paradigm for the design of
novel liquid metal dynamo experiments.