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Re: [TCML] Still stuck at 36"
Hi Gary,
A narrower gap spacing as a result of the pressurized gap would keep
the arc nearer to the metal which should help cooling and therefore
quenching.
I seem to remember hearing somewhere that a pressurized gap quenches
better. I think Dave Sharpe talked about this one time, but I could be
confused. But in any case just increasing the air pressure a little
should
compensate for the more conductive arc perhaps.
In any case quenching is not that important as long as it's acceptable
as shown by other experiments. In other words the reduction of gap
losses due to the shorter gap should outweigh the quench issue.
Of course power arcing is not acceptable. Quenching is heavily
influenced by spark loading, provided that power arcing doesn't occur,
and provided that the electrodes don't run too hot.
I think the better quenching of multi-segment gaps is partly due to
the higher losses in such a gap which dissipate the power and help
quenching via that mechanism.
John
--
-----Original Message-----
From: Lau, Gary <Gary.Lau@xxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sun, 25 Jan 2009 4:38 pm
Subject: RE: [TCML] Still stuck at 36"
I can't back any of this up with experimental evidence, but I would
guess that a
pressurized gap would exhibit worse quenching than a sucker gap. I
base this on
experiments that Terry did years ago, comparing a single segment gap to
a
multi-segment gap. The multi-segment gap showed superior quenching,
but higher
losses.
I suspect that things that stretch out or cool the gap plasma, like
keeping it
in contact with as much and as many pieces of metal as possible, tend
to enhance
quenching - the extinguishing of the arc. I'm guessing that the
shorter, more
conductive arc in a pressurized gap would be more difficult to
extinguish than
one stretched out further.
Regards, Gary Lau
MA, USA
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of futuret@xxxxxxx
Sent: Sunday, January 25, 2009 3:51 PM
To: tesla@xxxxxxxxxx
Subject: Re: [TCML] Still stuck at 36"
Hi Gary,
Well the gap loss improvement alone of the pressure gap would make it
a
superior design, yes.
I would think the quenching would be better too on the pressure gap.
So I don't see one factor as offsetting the other, I see the factors
as
being additive in a positive way. At least that's what I seem to
remember;
that higher pressure causes better quenching.
I made a mistake in my last posting. I meant to say that the air
pipes have to be connected to the opposite side (the pressure side),
rather than the vacuum side, of the vacuum motor unit. And as you
said,
this makes it a little harder to construct, but probably worth the
effort
I would think.
John
--
-----Original Message-----
From: Lau, Gary <Gary.Lau@xxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sun, 25 Jan 2009 2:54 pm
Subject: RE: [TCML] Still stuck at 36"
Hi John,
I don't recall if I made a careful performance comparison between the
sucker and
vortex gaps. At the time I was changing a lot of things on my coil,
and
probably since spark measurement is so subjective, I chose to just
focus on the
more quantitative gap loss measurements, which were unequivocal. See
http://www.laushaus.com/tesla/vortexgap.htm
So unresolved is whether quenching differences between sucker and
pressurized
gaps might offset the lower losses seen in the blown gaps. But if I
had to
guess, I would guess that the blown/vortex/hyperbaric gap would have
superior
performance. It's just a bit more difficult to build than a sucker
gap.
Regards, Gary Lau
MA, USA
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of futuret@xxxxxxx
> Sent: Sunday, January 25, 2009 1:08 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] Still stuck at 36"
>
> Theoretically, a sucker gap may work better if built as a
pressurized
> gap.
> In such case it won't be a sucker gap of course.
> Dr. R's hyperbaric gap is probably a pressure gap, not a sucker
> gap. After all, the word "hyperbaric" means "higher than normal
> atmospheric pressure. By using a pressurized air gap, this should
help
> reduce gap
> losses since pressurized air breaks down at a narrower gap setting
> than lower pressure air. Also pressurized air should quench better
> than lower pressure air. Just run the vacuum motor in reverse
> to produce the pressurized air. This is the concept Gary Lau
> used in his vortex gap. I remember that Gary used a sucker
> gap at first then switched to the vortex pressurized gap, but
> I don't remember if he saw a noticeable improvement in
> spark length. Perhaps Gary will comment.
>
> John
> --
>
>
> -----Original Message-----
> From: Phil Tuck <follies@xxxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Sent: Sun, 25 Jan 2009 4:07 am
> Subject: [TCML] Still stuck at 36"
>
>
>
> Hello.
> If you do go for a sucker gap as Dr R suggests, the 'normal'
distance
> for a
> gap may not always apply. After some head scratching I found out
that
> the
> vacuum that is created, alters the normal spark distance. (I'm now
> using 10K
> / 100ma on a 192 thou or 4.9mm gap)
>
> If I forget to start the suction (semi-industrial vac cleaner) my
gap
> will
> only start if the Variac is set around 220 volts (I'm UK based at
> 240volts)
> , whereas with the suction on, it will start at about 130 volts and
you
> can
> go as low as 90 volts running. I found you need good suction, vac
> cleaner or
> leaf vacuum cleaner (not a leaf blower) If you build it bigger than
you
> need
> you have capability for adding another NST as well. :-).
>
> Phil
>
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf
> Of tesla-request@xxxxxxxxxx
> Sent: 25 January 2009 05:09
> To: tesla@xxxxxxxxxx
> Subject: Tesla Digest, Vol 15, Issue 33
>
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