NEW ELECTROMAGNETIC PUMP BASED ON THE EFFECT OF MAGNETIC FLUX CONCENTRATION

Abstract

Eddy currents, being of either positive or negative nature, have recently gained more and more importance in their positive aspects. New devices that may be called “eddy current based” have been worked out in recent years. This paper intends to present a quite new application of eddy currents which is an electromagnetic pump of novel design. The pump can be employed to transport liquid sodium for the Fast Breeder Reactor or other conducting materials, like melted metals. Eddy currents are used here for two pur‐poses: the first one is the typical usage to create electromagnetic force (as in tube‐type linear motors or conventional electromagnetic pumps) while the second one is just newly invented. Normally, in linear motors or conventional electromagnetic pump the air gap is relatively big which makes the leakage flux increase. Then the electromagnetic force is strongly reduced. To overcome this negative influence of the air‐gap, i.e. to minimize the leakage flux a conducting plate of special structure is inserted into the exciting coil. The first idea of it was given by K. Bessho for high magnetic field generation. Although the purpose of the application presented here is different from the initial one the idea is common and it is likely to be used for other purposes too. The basic features of the pump resulting from both numerical and experimental investigations are presented in the paper.