DOUBLE-ELLIPSOID MIRROR FURNACE FOR ZONE CRYSTALLIZATION EXPERIMENTS IN SPACELAB

For crystallization experiments under micro-gravity in outer space, liquid or vapour zoning methods, using focused radiation as heat source, prove to be most effective with respect to weight and size of apparatus and energy consumption. A mirror heating facility for growing crystals in Spacelab is presented. It consists of two adjoined ellipsoids of revolution (a = 90 mm, b = c = 80 mm), in the common focus of which the movable and rotatable sample rod is located. Halogen lamps as radiation sources are located in the other two foci. The completely sealed mirror furnace can be operated in vacuo or protective gas atmospheres. Depending on size and properties of the sample, temperatures up to 2300 K can be attained. Power consumption is very low. Dislocation- free crystals of silicon (l = 120, diam. = 12 mm) have been produced by the floating zone method. Crystals of CdTe (l = 30, diam. = 10 mm) were grown by zone sublimation at 1120 K. © 1979.