Pressure change accompanying Alfvén waves in a liquid metal

K. Iwai¹ - K. Shinya¹ - K. Takashi¹ - R. Moreau²

¹ Department of Materials Processing Engineering, Nagoya University, Japan Furo-cho, Chikusa-ku, Nagoya, Japan, 464-8603
² Lab. EPM-MADYLAM, ENSHMG, BP 95, 38402 Saint-Martin d'Héres Cedex, France

Abstract
Alfvén waves were predicted by Alfvén \cite{1,2} and have been mainly investigated in the field of astrophysics and plasma-physics. Only few experimental investigations of Alfvén waves have been reported \cite{3, 4,5}, since, because of the strong and rapid ohmic damping in liquid metals, their propagation can hardly be observable in the presence of usually moderate magnetic fields \cite{6}. However, under the development of super-conducting technology, we can now easily obtain a strong magnetic field, in which this propagation phenomenon is fast enough, in comparison with the damping, to be observed in a liquid metal. In this research, an electrically-driven oscillation was imposed at the one end of a cylindrical liquid metal submerged in a strong magnetic field, whose intensity was enough for propagation of an Alfvén wave. The pressure change accompanying propagation of an Alfvén wave was measured at the other end. The magnitudes of the detected pressure changes under different experimental conditions are in fair agreement with the theoretically predicted ones. Figs 5, Refs 126.