Title: Developing a Method to Determine Electrical Conductivity in Meteoritic Materials with Applications to Induction Heating Theory (2008 Student Thesis),
Abstract: Magnetic induction was first proposed as a planetary heating mechanism by
Sonett and Colburn in 1968, in recent years this theory has lost favor as a
plausible source of heating in the early solar system. However, new models of
proto-planetary disk evolution suggest that magnetic fields play an important
role in solar system formation. In particular, the magneto-hydrodynamic
behavior of proto-planetary disks is believed to be responsible for the net
outward flow of angular momentum in the solar system. It is important to
re-evaluate the plausibility of magnetic induction based on the intense
magnetic field environments described by the most recent models of
proto-planetary disk evolution.
In order to re-evaluate electromagnetic induction theory the electrical
conductivity of meteorites must be determined. To develop a technique capable
of making these measurements, a time-varying magnetic field was generated to
inductively heat metallic control samples. The thermal response of each sample,
which depends on electrical conductivity, was monitored until a thermal steady
state was achieved. The relationship between conductivity and thermal response
can be exploited to estimate the electrical conductivity of unknown samples.
After applying the technique to various metals it was recognized that this
method is not capable of making precise electrical conductivity measurements.
However, this method can constrain the product of the electrical conductivity
and the square of the magnetic permeability, or ${\sigma}{{\mu}^2}$, for
meteoritic and metallic samples alike. The results also illustrate that along
with electrical conductivity {\sigma}, the magnetic permeability {\mu} of a
substance has an important effect on induction heating phenomena for
paramagnetic ({\mu}/{\mu}0 > 1) and especially ferromagnetic materials
({\mu}/{\mu}0 >> 1).