| 摘要 |
PURPOSE:To prevent the hole digging effect of a molten metal and to efficiently and safely melt and evaporate the metal in a crucible by monitoring the temp. of a crucible material and controlling a focusing coil to adjust the focus of an electron beam flux. CONSTITUTION:The electron ray flux 19 released from a filament 10 mounted to a filament power source is roughly adjusted in the beam flux width by a collimator 11 and is passed through an acceleration electrode 12, by which the energy thereof is amplified. The beam flux 19 is then deflected by a deflecting coil 13 and is finely adjusted by the focusing coil 14; thereafter, the beam flux bombards and heats the molten metal 2 in the crucible 1. The electron beam flux 19 is changed over to a small focus beam and large focus beam by a control circuit 5 via a driving circuit 8 for adjustment and a magnetic field generating power source 9. The focus of the flux 19 is adjusted or the bombardment and heating is stopped by the circuit 5 when the temp. increase of the crucible 1 is detected by a sensor 3 embedded in the crucible 1.
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