B.G.Zaslavsky
Received May 14, 1998
Principles of the high-productivity
automated pulling method of large-diameter alkali-halide single crystals
have been described. At the radial growth stage, the melt geometry is varied
continuously due to its level elevation in a conical crucible provided
by the melted raw material feeding controlled by the signal of a lifting
electrocontacting probe. The melt level remains constant at the stage of
the longitudinal growth. Time intervals between successive feeding operations
are used in the automated diameter control system as the informative parameter.
The automatic system based on this principle provides the crystal diameter
control to an accuracy better than 1% at the diameter of 400-450 mm and
the pulling rate of 6-6.5mm/h.
The method has been mastered in the industrial production of alkali-halide
scintillation single crystals.