(cryogenics) The depth beneath the surface of superconductor in a magnetic field at which the magnetic field strength has fallen to 1/e of its value at the surface.
(electricity) In induction heating, the thickness of a layer, extending inward from a conductor's surface, whose resistance to direct current equals the resistance of the whole conductor to alternating current of a given frequency.
(engineering) The greatest depth in an ultrasonic test piece at which indications can be measured.




