The Skin Effect

The proximity effect is the effect of eddy currents from one conductor’s changing current on the current flow distribution of another conductor. The skin effect, then, is an issue for alternating current on the self-same conductor.

The skin effect on AC transmission lines involves all of the telegrapher’s components. Most specifically though the electron eddy currents associated with, L, will be found especially at the boundary between the conductor and the dielectric. Fast moving electrons will eddy into the dielectric starting in the direction of current movement and then curling. Likewise, the current will eddy into the conductor. These eddy currents will add up from all around the conductors to oppose electron flow at the middle of the conductor. This means less current at the center of a conductor and more at the skin of the conductor.

As a surplus of electrons with a surplus of energy over the lattice is exposed to the conductor the charges will begin conduction as long as there is an energy gradient. The electrons will have the easiest time accelerating near the cladding of the conductor as they leap-frog their way to an electrical load or away from this load. Some electrons will escape the cladding boundary into the dielectric creating easier acceleration for subsequent electrons in the flow at the cladding.

The leap-frog effect above may be a capacitive phenomenon. Capacitance fundamentally refers to the capacity of the dielectric to store electrons. The accelerating particles accelerate down the boundary between the dielectric and the conductor. The conductor allows electrons to move quickly but if an electron jumps out of the lattice, into the dielectric and then back into the lattice, this class of electron moves the most quickly out of any governed by the parameters of the telegrapher’s equations.

The acceleration and faster relative velocities near the conductor-dielectric boundary can be seen as a type of efficiency. The electrons of an AC current are eddying in both directions and the non-eddy electron shoots down the middle efficiently. As well, with AC, there is a change of direction necessary and this change in direction is facilitated by the capacitance specified by the telegraphers equations. In reality that capacitance represents the charge that jumps off the conductor, into the dielectric, and then they make their way back into that self-same conductor.

The velocity or inertia of electrons eddying out around a given nucleus can knock other electrons out of their orbitals and into the curl of the flux of the electron flow. Again with more than 10²⁰ electrons traveling in a very small space the electron density means this may be fairly common. It will be less common for an electron to collide with a nucleus.