Re: triggered gap update and question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Hi Marc, Jim, All!

>i have been trying to get my triggered gap that is setup inside the
>pyrex tube to fire by field distortion, i'm using the setup posted by
>bert hickman and i'm using the 1/2" wide hard copper strip from the
back
>of a CRT of a television for the trigger electrode.
>the strip is wound around the outside of the tube, 1 1/8"dia in a
spiral
>and i haven't had any luck getting it to fire regularly. <snip>

If you have practical difficulties putting the electrodes in the tube
as per Jim's suggestion, you might try winding a full circle outside
the tube directly over each internal electrode and connect the two
circles to your trigger source.  If you look at a lot of U-shaped
flashtubes, you'll see that the trigger electrodes there are wound
outside the glass directly around the electrodes fused into the glass,
so that there is ionisation between the internal electrode and the
trigger applied to the outside of the glass.  The ions then migrate
internally within the flashtube, but these things are of course at low
pressure (a few mmHg) and I don't know how effective that will be with
your setup.  It might be physically easier to try as a "quickie"
though before attempting to stick electrodes inside the tube.

Another idea would be to extend the diameter of the internal
electrodes e.g. with a bit of aluminium foil or copper wire or a thin
metal disk/washer (it won't be carrying heavy current so the material
shouldn't matter) so that the distance between the trigger electrode
outside the glass and the main electrodes inside is reduced and also
so that there is a kind of "point" on the inside electrode aimed at
the external trigger electrode to promote ionisation.  I'd just be a
little concerned that you may in that case be liable to get the main
spark punching through the glass if you make the distance very small,
EHT at rf likes to do things like that :-(

Dunckx
Geek#1113 (G-1)