RE: [TCML] Ultra-high speed movie of lightning arc channel formation

["Lau, Gary" <Gary.Lau@xxxxxx>]

Hi Jeff,

Those are beautiful images, more from the realm of sci-fi movies than from any TC photography I've previously seen.  I'm not sure it constitutes high speed, but awesome to look at none the less!

But I don't have a good sense of just what it is I'm looking at.  I understand that you use a very low-value mains fuse to limit the on-time of the coil, but I don't understand the relationship of the film (positive photo paper?) and anything else.  What is it that's in contact with the paper?  Are we looking at surface tracking across the paper, or something else?  What is the scale?  What are the coil specs?  Did you develop the film?

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Jeff Behary
> Sent: Monday, August 11, 2008 7:08 PM
> To: Tesla Coil Mailing List; jeff_behary@xxxxxxxxxxx
> Subject: RE: [TCML] Ultra-high speed movie of lightning arc channel formation
>
>
> Bert,
>
> This is not so high-speed, but I did a few tests before as Lichtenberg Figures
> directly on photographic film or paper.  For the coils, I used small glass fuses, the
> fastest-blowing at the smallest amperage I could find (at the local hardware store).
> The concept was pretty simple, simply turn on the coil and the fuse was instantly
> blown in a fraction of a second.  (what fraction, unfortunately, I don't know).  What
> is interesting, is the amount of sparks generated (and the branches, effluves,
> brush) in such a short amount of time.  Granted, a 1/100th or 1/20th of a second
> may be considered a long time for this sort of exposure, compared to high speed
> cameras, but maybe not everything can be captured quite as easy with a camera
> as by direct contact.  If only there was high-speed exposures possible directly on
> film.  (Sounds like a new invention!)
>
> http://www.electrotherapymuseum.com/2005/2005-06-
> 23/images/CencoDC0001ic.jpg
> http://www.electrotherapymuseum.com/2006/KinDis1/images/ED0009a.jpg
> http://www.electrotherapymuseum.com/2005/2005-06-
> 23/images/CencoDC0000ic.jpg
> http://www.electrotherapymuseum.com/2005/2005-06-
> 23/images/CencoDC0002ic.jpg
> http://www.electrotherapymuseum.com/2005/Film22May/images/FischerCenco000
> 1.jpg
> http://www.electrotherapymuseum.com/2005/Film22May/images/FischerCenco000
> 8.jpg
> http://www.electrotherapymuseum.com/2005/2005-06-14/images/Glossy20002i.jpg
> http://www.electrotherapymuseum.com/2005/2005-06-14/images/Glossy20001i.jpg
> http://www.electrotherapymuseum.com/2006/KinDis1/images/ED0005b.jpg
> http://www.electrotherapymuseum.com/2006/KinDis1/images/ED0007a.jpg
>
> I can try to recreate some of these at a later date with a more precise way of
> measuring time, maybe an X-Ray timer or something similar.  I'm sure there is
> something this half of the century that is more accurate than whats in my junk pile.
>
> It would be interesting if a roll of photographic paper/film, large format, was rapidly
> moving, like being transfered from a full roll to an empty roll spinning in a lathe, with
> the coil discharging in one spot (say, centered on the roll's width).  If the
> mechanical constraints worked out so that the paper/film travelled smoothly, even
> at high speed, it would be an interesting experiment to see Lichtenberg figures at
> so many feet per second, how many, and how they change.  Damn hard to develop
> and fix such a long photo, but still, it would be fun.
>
> I've seen the slow branching effect before with Tesla Coils.  A coil that can give a
> spark, say 3 - 4 foot long, operated at a fraction of the power normally used (less
> than 100 watts, for example) with the spark gap open just enough for it to fire once
> or twice a second (but not cease to fire).  The sparks become very branching,
> static-like, and strangely seem to  low down just enough for you to make out the
> invididual branches.  Unfortunately you need your nose pretty close to the sparks to
> really study this, and I've had a few too close for comfort.  Despite the low current,
> these sparks are beautiful but not very friendly to get tangled with.
>
> Jeff

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