The Dissipation of Magnetic Energy in an Ionized Gas

Abstract

A general formula is derived for the rate of dissipation of magnetic energy in an ionized gas. The formula is used to confirm Piddington's value for the conductivity effective in producing dissipation. It is shown that, contrary to Piddington's assertions, an effective electric force must be taken into account when considering currents in the presence of a pressure gradient; however, this effective electric force has little effect on the dissipation. Piddington's results are completed by a general discussion of conductivity in a partially ionized gas. The results are applied to dissipation in interstellar gas; the effect of the magnetic field on the conductivity is shown to increase the rate of dissipation up to a point where the dissipation is not insignificant.