Natural Science Forum / Physics / Fusion / February 2008

The mean free path of an ion depends on the pressure at low pressures this
in much longer than at high pressures.

In an electric field an ion pickes up energy from the field and the longer
it can fly before hitting another ion the higher the energy it can aquire.

This means that the probability of the enegy being sufficient to overcome
the energy barrier (due to the coloumb force) is greater. There is a tunnel
effect which simply means that at low energy the probablity of fusion is
lower than at high energies.

Now at very low pressures the mean free path can be meters so if the coil
has 80 volts per turn and each turn has a length of 0.5 mm as it has near
the axis then the field strength is 80/005 V/meter or 16000 volts/meter at
smaller diameters the field strength is higher and rises as 1/r from the
axis. As r>0 this > infinity making ion energies very high. When the energy
is high enough the frequency of fusion as a result of ion collissions
increases.

That is how a coil can start fusion reactions in a hydrogen plasma.