The New Mexico αω dynamo experiment: Modelling astrophysical dynamos

S. A. Colgate^1,2 - V. I. Pariev^2,3 - H. F. Beckley¹ - R. Ferrel¹ - V. D. Romero¹ - J. C. Weatherall¹

¹ Department of Physics, New Mexico Institute of Mining and Technology, NM 87801, USA
² Theoretical Astrophysics Group, T-6, MS B288, Los Alamos National Laboratory Los Alamos, NM 87545, USA
³ P.N. Lebedev Physical Institute Leninsky Prospect 53, Moscow 117924, Russia

Abstract
TA magnetic dynamo experiment is under construction at the New Mexico Institute of Mining and Technology. The experiment is designed to demonstrate in the laboratory the αω magnetic dynamo, which is believed to operate in many rotating and conducting astrophysical objects. The experiment uses the Couette flow of liquid sodium between two cylinders rotating with different angular velocities to model the ω-effect. The α-effect is created by the rising and expanding jets of liquid sodium driven through a pair of orifices in the end plates of the cylindrical vessel, presumably simulating plumes driven by buoyancy in astrophysical objects. The water analog of the dynamo device has been constructed and the flow necessary for the dynamo has been demonstrated. Results of the numerical simulations of the kinematic dynamo are presented. The toroidal field produced by the ω-effect is predicted to be B_φ ≅ (\Rm /2π) B_poloidal ≅ 20 ×B_poloidal for the expected magnetic Reynolds number of \Rm  ∼ 120. The critical rate of jets necessary for the dynamo self-excitation is predicted from the calculations to be a pair of plumes every 4 revolutions of the outer cylinder. For reasonable technical limitations on the strength of materials and the power of the drive, the self-excitation of the dynamo appears to be feasible. Figs 9, Refs 15.