Magnetic fields to control convection

H. Uetake¹ - N. Hirota^1,2 - Y. Ikezoe¹ - J. Nakagawa³ - K. Kitazawa^1,2

¹ Dept. of Applied Chemistry, Faculty of Engineering, University of Tokyo 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
² CREST, Japan Science and Technology Corporation, 4-1-8 Hon-cho, Kawaguchi, Saitama 332-0012, Japan
³ TDK Co. LTD., Materials Research Center, 570-2 Matsugashita, Minamihatori, Narita 286-8588, Japan

Abstract
Some interesting phenomena have been observed in the motion of insulating fluids under magnetic fields. The phenomena are acceleration of water vaporization, the enhancement of oxygen dissolution into water, and an action of magnetic wind tunnel. The mechanisms of these phenomena turned out to be similar to each other explained by magnetically induced convection in the coexistence of the magnetic-field gradient and a magnetic-susceptibility gradient. The insulating fluids employed in this study are dia- or paramagnetic substances such as water and air. Various demonstrations have been carried out in order to show how the insulating fluids behave under strong magnetic fields up to 12 T. In particular, it has been found possible to create a large volume magnetic wind tunnel(ca. 300 l/min) by utilizing temperature variation of magnetic susceptibility of the air. And this technique can be used to control thermal convection without any mechanically driving parts. Magnetic fields may find the field of potential application in control of gas convection in various gas processes. Fig. 11, Refs. 10.