Model based optimization of some growth process parameters of a Nd:YAG cylindrical bar grown by edge-defined film-fed growth (E.F.G.) method
by
Liliana Braescu
Department of Mathematics, Polytechnical University of Timisoara, P-ta Regina Maria, No.1, 300004 - Timisoara, Romania
Coauthors: Agneta M. Balint (Department of Physics, The West University of Timisoara), Stefan Balint (Department of Mathematics,The West University of Timisoara)

The main purpose of this paper is to find those values of the pressure p, die radius r0, pulling rate v and temperature T0 at the meniscus basis which assure the growth of a Nd:YAG monocrystal (blue laser) cylindrical bar with a prescribed diameter 2rf and for which the non-uniformities of the surface of the bar, due to small uncontrollable oscillations of the pulling rate v and melt temperature T0, are minimum possible. For a set of the values of p and r0 we find those couples (v, T0) for which the grown crystal radius is equal to a desired radius rf . For a pressure p and a die radius r0 we find that couple (v, T0) for which the amplitude A of the change of rf, due to small oscillations of v and T0, is minimum. Finally we identify the pressure p, the die radius r0 and the (v, T0) couple for which the amplitude A is minimum possible.

Numerical results are given for a Nd:YAG cylindrical bar of 5 (mm) diameter, grown in a furnace in which the vertical temperature gradient is k=33 (K/mm) for the following three types of uncontrollable oscillations of v and T0: v=±0.001 (mm/s), T=±1 (K); v=±0.01 (mm/s), T=±10 (K) and v=±0.02(mm/s), T=±20 (K), respectively.

Date received: December 18, 2003

Copyright © 2003 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cakt-17.