Re: fluorescent tube question

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

>
> > Your hand and body can act as a capacitively coupled antenna and
increase
> > the field somewhat to get it to glow better.
>
> I wonder weather it is that you make a better return path, or a better
> static receptor?

probably some of both... There is a field enhancement issue (any conductive
object affects the E field around it) and a increased current flow issue
(which, is of course, related to the conductive properties of humans, etc.)
>
>
> >
> > Watch out when doing this that you don't get a streamer to one end of
the
> > tube while you hold the other.  The tube is a reasonable conductor for a
> > direct strike, and you WILL get shocked.  (First hand personal
experience
> > here....)
>
> OOOH, my buddy holding one end to his groin, Always make me shiver!!

Like the stories about third rails and the call of nature

>
>
> >
> > Neon signs will also light up, but in my limited experience, it takes
more
> > field to get them to glow.... probably some geometry and gas pressure
> > effect...
>
>
> I was given a six foot length of red sign tubing, I have found that the
> "glow" seems to stop at certain points were the field strength must fall
> of? It can be moved around a source like a vttc or disruptive, and at a
> circular point around the parameter, a field strength can be seen?

Exactly... what you have is a handy field strength indicator...


>
>   after all, neon signs need many kV to "strike" (hence the NST at
> > 15 kV).. Fluorescent ballasts only kick out 500 or so volts to start a 8
> > foot long tube.
>
> Good point! But the fluorescent tubes conduct better at close range. The
> glass is "REAL" thin, arcs pierce neon very rarely.

The thickness of the glass wouldn't make much difference to exciting the gas
inside (that's more a function of the E field).  As for conducting
significant currents... at 100 kHz, 20 or 30 pF (the capacitance of your
hand around that "conductive" mercury vapor) is a fairly low impedance.  If
you happen to be touching the electrodes or end cap?