Influence of horizontal static magnetic field on the stability of electromagnetic levitated Cu molten droplet

For an electromagnetically levitated (EML) molten droplet, there usually exist some unstable factors, such as internal fluid convection, quick spin and horizontal displacement and so on. As a result, stabilizing the droplet is very important for EML technology. In this paper, a horizontal static magnetic field is imposed on an EML Cu droplet through a U-shaped static magnetic component. The shape oscillation of a Cu droplet is recorded continuously under different magnetic field intensities using a high speed camera. The effects of static magnetic field on the oscillation frequency, amplitude and spin angle of the droplet are analyzed from the recorded data of droplet shape. The result shows that when the strength of the static magnetic field exceeds 0.3 T the solid Cu is levitated statically without any spin and horizontal movement. For molten Cu droplet, its amplitudes of the R-, A and Dmax are reduced by 25%, 76% and 60% respectively when a static magnetic field with 0.15 T is imposed. With the increase of magnetic field strength the amplitude and frequency of oscillation decease continuously. However, when the intensity of the static magnetic field is 0.3 T, its frequency is 1 Hz higher than that when the intensity of the static magnetic field is 0.2 T. Finally, the result indicates that the horizontal static magnetic field can inhibit the spin of the levitated droplets. For instance, when the strength of the magnetic field is 0.53 T the droplet spins are within a very narrow angle of 10°, which is quite smaller than in the case without static magnetic field. These results exhibit that the imposed horizontal static magnetic field can effectively improve the stability of electromagnetic levitated droplet.