The stepped and tapered furnaces are known to furnace designs reducing the temperature gradients in the samples. However, the heat flow in the axial direction near the radial center produces
steep temperature gradients, which cause segregation of melts in the radial direction in the axial center in the samples.
In order to prevent this heat flow, we place heater rods at both ends of the cylindrical furnace. This design renders it possible to prevent melt migration in partially molten rocks.