>> What is the temp of the plasma in the spark gap? In the discharge?
> Very hot, thousands of centigrade is not unusual.
>> Fire/plasma conducts, why?
> A plasma is a gas that has had more energy pumped into it than will allow
> electrons to stay with their original nuclei. The characteristic glow is
> caused because photons are emitted whenever electrons jump up or down in
> energy levels. Ordinary gases don't conduct significantly, because few if
> any free electrons can move around - they are all bound to nuclei. Plasmas
> do conduct precisely because there *are* lots of free electrons.
> Apologies to any trained physicists out there - I know this is a serious
Not really, this is actually a very succint description, I would mention
only one insignificant detail, the photons are emitted only on electrons
dropping into lower energy shells. They absorb energy in jumping to higher