NUMERICAL CALCULATION OF THE F COLOR CENTERS DISTRIBUTION IN ADDITIVELY COLORED ALKALI HALIDE CRYSTALS
Pages 125-128
Liliana Lighezan, Carmen Stelian, Dana Susan - Resiga, Irina Nicoara
Abstract
In this paper, we have realized a numerical simulation of the additive coloring of crystals, by solving the diffusion equation in the time dependent case. The numerical modeling is performed by using the finite element commercial code FIDAP. Using two-dimensional (2D) FIDAP numerical simulations, we have computed the distribution of the F color centers, during the additive coloring of the KCl crystal. We have found that the coloration of a KCl crystal, with the dimensions 2 mm × 2 mm × 20 mm, the diffusion constant D = 8 . 10-6 cm2/s at temperature T = 600 K and the diffusion characteristic time ?D = 8.4 minutes, becomes very uniform after approximately 30 minutes. This result is in a very good agreement with the experimental measurements. A numerical computation of the coloration time for KCl crystals with various thickness values (4 mm, 6 mm, 8 mm and 10 mm) has also been performed, using two-dimensional (2D) geometry. The dependence of the coloration time on the crystal thickness has been analyzed.