Low Gradient Furnace (LGF)This is the first European furnace insert for MSL. It is developed to conduct experiments in the field of Bridgman crystal growth. The LGF consists of two heated cavities separated by an insulating, “adiabatic” zone. It can establish restricted, but well-controlled gradients between two stable temperature plateaux. Crystal growth is performed by translating the furnace over a stationary sample. Thermomechanical stresses in the grown crystal are minimised by keeping the solidified part of the sample in the heated cavity throughout processing. This insert can also be used for thermo-diffusion experiments, maintaining the furnace stationary, and using only the temperature gradient capability. Isothermal experiments can also be carried out utilising suitable sample/cartridge configurations.
LGF performance characteristicsThe LGF consists of seven separately controlled heating zones. The heater elements are based on pyrolytic boron-nitride/pyrolitic graphite heater technology, with carbon composite diffusers to provide thermal uniformity. The LGF provides high-stability thermal control by sapphire optical fibre thermometers (OFT) and a high performance control algorithm. The achievable temperature gradients depend on cartridge design and on the sample’s thermal conductivity. An electromagnet provides for controlled stirring of the melt by a rotating magnetic field.
LGF technical data: