Diagram of the laboratory facility: a) in the process of heating and melting; b) in the process of draining the melt. 1. Dry box chamber; 2. Air evacuation hole; 3. Argon supply; 4. Quartz tube with a filter; 5. Vertical resistance furnaces; 6. Quartz tube with a crucible; 7. Alundum crucible for receiving the melt after the filter; 8. Alundum crucible with melt; 9. Branch pipe for pumping air; 10. Ceramic stand.