微重力环境下横向旋转磁场对热表面张力流的影响

微重力环境下外加磁场可以有效地控制浮区法晶体生长中的热表面张力流,从而提高半导体晶体生长的质量。在比较相同强度（7 mT）的横向静态磁场与横向旋转磁场对热表面张力流影响的基础上,研究了外加横向旋转磁场（旋转频率50 Hz）对三维半浮区熔体热表面张力流的控制。结果表明：横向旋转磁场对熔体产生周向搅拌作用和轴向抑制作用,其有助于三维热表面张力流转变为二维轴对称流动。浮区法晶体生长中,横向旋转磁场是一种比较理想的熔体对流控制方法。

Effects of transverse rotating magnetic field on thermocapillary flow under microgravity

Semiconductor melt is electrically conducting, which makes it possible to apply magnetic fields to control the thermocapillary convection induced by surface tension in the floating zone under microgravity, and ultimately to control grown crystal quality. In the present paper, based on the comparison between the transverse static magnetic field and the rotating magnetic field(RMF), we focuses on the effects of RMF on thermocapillary convection. Results indicate that in the RMF, the induced Lorentz force is effective in stirring the melt in the azimuthal direction and suppressing axial convection, and both effects are beneficial for the three-dimensional melt convection returning to a steady axisymmetric flow. The RMF is a promising method for convection control in floating zone for semiconductor crystal growth.