Re: Florescent Foolishness

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Florescent Foolishness
From: Tesla List <tesla-at-stic-dot-net>
Date: Wed, 26 Nov 1997 19:31:38 -0600
Approved: tesla-at-stic-dot-net

From: 	ghunter-at-mail.enterprise-dot-net[SMTP:ghunter-at-mail.enterprise-dot-net]
Sent: 	Wednesday, November 26, 1997 4:48 PM
To: 	Tesla List
Subject: 	Florescent Foolishness

I've been probing the secrets of the universe with a burned out 
florescent tube and a Tesla coil.  Actually, I've just been showing 
off for the kids.  My latest plaything is a "soft white" tube about 
4' long and about 1" in diameter.  I've taped it to the end of a wooden 
yardstick.

-The Dark Spot-

When the tube is within 5 or 6 feet of my TC, it glows like mad. 
When I allow a spark to actually jump to it, it glows even brighter. 
Big deal.  But when I have the tube near the secondary but just out
of reach of sparks, I've noticed a dark spot.  The dark spot is
about 4" long and coresponds to the point on the tube that is
closest to the secondary.  The rest of the tube, before and after
the dark spot, glows brightly.  As I move the tube away from the
secondary, the dark spot becomes less distinct.  Hmmm...

-The Orange Spot-

Whether in direct contact with a spark or not, the TC excited tube
glows the same color as it once did in a light fixture--daylight
white. However, if I allow a spark to jump to the glass envelope of
the tube instead of the AC prongs, It glows bright orange at the
point where the spark touches it.  The orange spot is about 4" long. 
The rest of the tube glows the normal blue-white color.  How does it
make orange light around the site of spark contact?

-Field Shape-

I can roughly trace the RF field shape around the secondary with
the tube by moving it around like a wand.  With a toroid terminal on
top, the brightest glow occurs when the tube is on either side of
the secondary.  Straight out from the middle of the secondary
winding is most intense of all.  Directly above the toroid is the
weakest glow (nearly dark).  The excitation field seems to be toroidal,
surrounding the secondary like a fat donut.  With a sphere top
terminal, the RF field seems much more isotropic, with respectable
glow even directly above the secondary.  I was vaguely aware of the
shielding properties of toroids, but I didn't expect to
see such a drastic difference in RF field shape.

Having way too much TC fun in cold, muddy East Anglia,

Greg