Re: Ball Lightning in a different lab

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: William Beaty <billb@xxxxxxxxxx>

On Sat, 25 Jun 2005, Tesla list wrote:

> spaced windows, can form a slot tuned, with lots of gain, antenna. Once so
> induced, standing waves could form a high current or voltage node and
> result in a BL. Get a microwave or ARRL book and check out slotted phased
> arrays. Not unlike some UHF TV transmitter antennas.
> Regards, oh yes, let me add the word Tesla and Tesla Coil in here for the
> word counter.

Everyone here should be aware that if you forget to put a resistive load
inside a microwave oven, then you've got a high-Q, high frequency, high
voltage resonator driven by about a kilowatt RF source at the same
frequency.   It's 2.5GHz Tesla coil.

The e-fields inside an empty microwave oven are close to the breakdown for
air because of resonant rise.  Stick some torn aluminum foil in an
otherwise empty microwave oven cavity, and most of the time you'll trigger
corona discharge.  Even the sharp tines of a fork, or the burrs on the
edge of a soup can will do this.  But the corona plasma is a good
absorber, so it eats nearly the entire oven output and acts more like a
blow-torch flame than a spark.

If you worry about stressing your oven, note that its worse to run the
oven with nothing inside, than it is to run the oven with a huge writhing
plasma flame.  If the oven is otherwise empty, then even a slight absorber
of RF will become extremely hot (including the ceramic port at the end of
the magnetron!)  If there's a cup of water in there, or a big hot corona
discharge that vaporizes paint and melts metal, your magnetron is much
happier.

PS, it helps to raise the RF voltage if you remove ALL other absorbers
from the oven cavity, including the large glass bottom plate.  If you
leave the plate in, but remove everything else, the plate will act as the
only remaining load, and become quite hot.


(((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))
William J. Beaty                            SCIENCE HOBBYIST website
billb at amasci com                         http://amasci.com
EE/programmer/sci-exhibits   amateur science, hobby projects, sci fair
Seattle, WA  206-789-0775    unusual phenomena, tesla coils, weird sci