Reduction of silicon crust on the crucible walls in silicon melt purifying processes with electron beam technology by means of low-frequency traveling magnetic fields

A. Krauze¹ - A. Muiżnieks¹ - K. Bergfelds² - K. Janisels¹ - G. Chikvaidze²

¹ Faculty of Physics and Mathematics, University of Latvia, 8 Zeļļu str., Rīga, LV-1002, Latvia
² Faculty of Physics and Mathematics, University of Latvia, 8 Zeļļu str., Rīga, LV-1002, Latvia

Abstract
Electron beam technology could be used for low-cost silicon melt purification in the solar-grade silicon production from metallurgical-grade silicon. Silicon is melted by an electron beam in a water-cooled copper crucible, due to which a crust of solid silicon develops on the crucible walls. Low-frequency travelling magnetic fields (TMF) can be used to increase melt stirring, which would lead to the reduction of the crust thickness and increase in amount the molten silicon. In this paper, we describe a simplified model for modelling the melt flow and heat transfer under the TMF influence in crucibles with electron beam heating and present the calculation results, which show that a significant crust reduction can be achieved with the TMF generated by inductors with the 10000~Aw current amplitude. Also, the required net absorbed power by the melt is numerically evaluated. Tables 2, Figs 9, Refs 15.