How can I heat one side of a work piece by induction without heating the component to the core? What should the inductor look like so that a homogeneous magnetic field distribution and, above all, uniform heating can be achieved? Spiral pancake inductors have too large turns, so that the inductor protrudes too far above the sample and the sample is not heated uniformly (tube diameter of 4 mm for sufficient cooling). Do I use a ferrite core?