Thermocapillary convection of liquid bridge under axisymmetric magnetic fields

Three-dimensional numerical simulation of thermocapillary flow in liquid bridge model is performed. The effects of the magnetic field, including both axial uniform magnetic field and axisymmetric non-uniform magnetic field generated by circle coil, on the thermocapillary flow of semiconductor melt are investigated. For a three-dimensional thermocapillary flow, the axial magnetic field and the axisymmetric nonuniform magnetic field suppress convection effectively, and the three-dimensional thermocapillary flow tends to become an axisymmetric one. Under axial magnetic field, the convection in central core region becomes very weak, and in the meantime, the energetic thermocapillary flow is squeezed toward free surface. While the axisymmetric non-uniform magnetic field generated by single coil is applied on the melt of liquid bridge, the convection structure is similar with that under axial magnetic field. By applying the axisymmetric CUSP magnetic field generated by two coils, convection structure depends on the symmetric plane position of two coils (SPPTC), the surface tension flow penetrates the whole liquid bridge and no stagnant core in the inner part of the melt is observed when SPPTC locates at z^* = 0.5, which is thought as a more favorable convection structure to alleviate radial dopant segregation in floating zone crystal growth.