Re: Sparks thru the core

Hi all,  Thanks to everyone participating in this discussion. The
ideas are interesting and thought provoking. As Jim Oliver notes,
sparks definitely travel much further when they have an insulator
to track along. I first noticed this when I built a Van de Graaf
machine while at primary school. I have noticed on odd occasions
when running a coil badly overcoupled, the tendency to get bolts
of lightning tracking the full length of the coil over the outside
of the windings - a lack of varnish here spells doom. Unfortunately
the coils have been capped at the top so it has not been possible
to check for inside/outside preference. Perhaps Ed could risk his
free-standing coil ? (I shouldn't be so mean :-)  I also have
plans to build a free-standing coil so have more than a passing
interest in ideas expressed on this topic.
     My two cents worth is this : considering a single secondary
turn; it is shielded from seeing vertically beyond its immediate
neighbouring (above and below) turns. But it is not so shielded
from seeing turns on the opposite side of the coil (consider looking
down the coil from top to bottom).
     Please keep the ideas flowing. There are things to be explained
and whenever that occurs, NEW methods can emerge.