Effect of magnetic field on thermal convection of phosphate glass melts

Flow behaviour has been observed in binary alkali phosphate glass melts (xR₂O-2P₂O₅: R Li, K ; x 1, 3) under vertical magnetic field up to 3 T. The flow velocity of thermal convection decreased gradually to about one-third of the velocity at 0 T with an increase in magnetic field up to 1 T in the melt of low alkali content glass, and reached the constant value, under the condition of BdB/dz < 0. In contrast, the flow velocity was almost unchanged in the melt of high alkali content glass up to 3 T. On the other hand, the flow velocity decreased gradually to half of the velocity at 0 T with an increase in magnetic field in the melts of high alkali metal content glasses up to 3T, under the condition of BdB/dz> 0. The velocity decreased more gradually in the lithium containing melt than in the potassium containing melt. It was deduced from these observations that the flow behaviour under magnetic field was the resultant of balance between the thermomagnetic convection under the gradient of field and the electro-magnetic force by induced current.