Re: single shot
Subject: Re: single shot
From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Date: Fri, 17 Nov 1995 15:39:54 +1200
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Ed Harris writes.....
> I have been thinking about the formation and maintainance of arcs
> from telsa coils. Do the long secondary arcs that I see from various people
> form in one ring-down time from the secondary, or are they formed from
> multiple ring-downs?
Multiple in my experience. Turns out the sparks go far farther with
repetitive ionization from multiple shots than the theoretical
voltage would suggest. Hence I regard spark length as a non-starter
for indicating actual output voltage.
> Has anyone ever done single-shot discharge experiments
> where the secondary is only allowed to ring-down once?
Yes, many times. The result is a spray of feathers as the secondary
rings down. Some are often a bit thicker than others showing some
of the effects mentioned above. Tesla speculates in his early work
that each feather represents a cycle of oscillation.
> Also, I know that the resistance of an arc goes down with
> increasing current. So the voltage of the secondary should drop
> considerably after the arc forms. It would be intersting to get relative
> voltage readings pre and post arc. A scope probe placed far enough away in
> a non arcing direction might allow one to see this effect.
Done it, and yes. The better the spark, the quicker the oscillation
dies. With a discharge rod positioned close enough to the terminal,
the "feathers" disappear as the current flashes back and forth in
a single discharge channel.
Loose pri-sec coupling means that the system cannot behave like
a voltage source. IMO Vo must drop with loading.