Re: Jacob's Ladder

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

Original poster: "Steve Greenfield by way of Terry Fritz <twftesla-at-qwest-dot-net>" <alienrelics-at-yahoo-dot-com>

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Michael H Nolley by way of Terry
> Fritz <twftesla-at-qwest-dot-net>" <nolleym-at-willamette.edu>
>
> > I was wondering if the electrodes of a jacob's
> ladder could be put inside a
> > sealed jar filled with low pressure argon or
> helium so a longer arc could be
> > obtained from a lower powered source? This way a
> flyback that could produce a
> > 1/2-1" arc might be able to do two inches and have
> a thicker arc
> resembling the
> > streamers of commercial plasma globes.
>
>     Remember, convection produces the upwards motion
> of the arc, so behavior is
> likely to be very different in a sealed vessel, or
> one with different
> gases.  It
> could still be very interesting, however.  It might
> move very slowly, which
> would
> be a cool effect.
>             --Mike

It could allow the arc to rise much higher just
because of the lack of room air movement disturbing
it.

My Jacob's Ladder is "sealed" in a rectangular cabinet
with plexi front and back, but it is not really
sealed. There are gaps on the top and bottom edge of
the plexi and there is a small computer CPU fan that
blows air out through a flexible hose that you stick
out a window.

To the original poster: the length of the arc is
determined in large part by the max current of the
transformer. IE, there must be enough power to keep
the arc heated to a plasma.

I've been meaning to create an arc and measure the
voltage across it once a hot arc is created. I've read
accounts that claim less than 100V across a hot arc
but I've never measured it.

I do know the voltage required to sustain the arc is
low compared to the 9 to 15KV NST usually used for
them. I researched on the web before building mine and
saw people claiming to build them with MOT using
things like 1KW heaters for ballast. IE, you need to
take the same precautions against overcurrent that you
do when building a Tesla coil.

Since it takes a higher voltage to start than to
sustain, how about a lower voltage with a spark
trigger just like a triggered spark gap on a Tesla
coil? Sense the current flow and when it drops to zero
it sets off the starting spark again.

I know we're off topic for the Tesla list. If you'd
like we can move the Jacob's Ladder discussion to the
Mad Scientists list at
http://groups.yahoo-dot-com/group/mad_scientist



=====
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