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 non-uniform 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.

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Measurements have been performed on ion cyclotron oscillations inducedby a small emissive disc plate floating in a magnetized collisionlessplasma column. The oscillations are observed when the emission is solarge that the disc potential is higher than the plasmapotential. This means that the oscillations are generated even in theabsence of dc electric current passing through the plasma column ifthe disc potential is positive with respect to the plasmapotential. The situation is in contrast with the case of applyingpositive potentials to a small plate to generate the ioncyclotron oscillations, where a dc electric current is induced alongthe plasma column. Main features of the oscillations are consistentwith the “potential-driven” model for the generation of ioncyclotron oscillations.

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The thermocapillary flow in half-zone liquid bridges of low-Prandtl-number fluids, when the surface is partially confined by thin solid walls, is investigated numerically. The linear stabilities to three-dimensional disturbances and their physical destabilizing mechanisms are addressed for the axisymmetric steady flows, which are formed by changing the aspect ratio of the liquid bridge, the axial position of the free surface, and the ratio ξ of the free surface length to the full liquid height. A partial covering of the free surface adjacent to the significantly affects the axisymmetric steady toroidal vortices, especially the ellipticity of the streamlines. By decreasing ξ the effect of the elliptic mechanism on the energy production of the disturbance diminishes, leading to four distinct instability modes, including two oscillatory modes. Each of the instability modes essentially consists of the elliptic instability and / or the centrifugal instability. For a sufficiently small ξ , the instability appears to be purely centrifugal. The range of the ξ in which the oscillatory modes take place becomes narrower, the smaller the aspect ratio of the whole domain. If the free sueface is assigned on the cooling side, the instability is always the same as that for the unconfined half-zones.

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In order to have better predictions for the FZ growth of Si/Ge crystal under microgravity field, a numerical simulation of the Marangoni convection in a three-dimensional Full-zone configuration was performed. In early stages of the simulation, the flow and temperature fields were still 2-dimensional, and 2 vortexes with the same size existed in the melt. However, the concentration field exhibited a three-dimensional behaviour even the flow and temperature fields were still axisymmetric. As time proceeds, the flow, temperature and concentration fields become three-dimensional. In the case of large Marangoni number, size of the vortexes periodically changed in spite of assumed axisymmetric thermal boundary conditions. It was shown that rotation of the crystal and feed was beneficial in growing axisymetrically uniform crystals.

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