The small furnace is based on the "hot-finger" principle. It is cooled
by radiation only, and there are there is only one radiation shield,
mountable on the hot finger (inner diameter 28 mm, inner length 80 mm).
This leads to a relatively large temperature gradient on the sample.
But as there are three thermocouples (one on the hot finger and two freely mountable), one
can at least get an idea about the gradient.