Thermoelectricity - Thomson Effect

Thomson Effect

In many materials, the Seebeck coefficient is not constant in temperature, and so a spatial gradient in temperature can result in a gradient in the Seebeck coefficient. If a current is driven through this gradient then a continuous version of the Peltier effect will occur. This Thomson effect was predicted and subsequently observed by Lord Kelvin in 1851. It describes the heating or cooling of a current-carrying conductor with a temperature gradient.

If a current density is passed through a homogeneous conductor, the Thomson effect predicts a heat production rate per unit volume of:

where is the temperature gradient and is the Thomson coefficient. The Thomson coefficient is related to the Seebeck coefficient as (see below). This equation however neglects Joule heating, and ordinary thermal conductivity (see full equations below).