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Re: Jelly Beans ????

On Fri, 19 Apr 1996 marcus@ttphysik.uni-duisburg.de wrote:
 
> Dear Bill, 
> Nice philospohy, but please can you tell me why the jelly beans, 
> when created by this process, didn't appear in a DC discharge?
> 
> This effect stems from plasmodial oscillations interfering with the frequency
> of the external electric field. 
> 
> Marcus Thielen

Hi Marcus!  The first time I saw jellybeans was in a DC Geissler(sp?)
tube.  The jellybean pattern was extremely responsive to nearby permanent
magnets, and individual "beans" would split into more, or several would
meld into one when the magnet was waved around.  Changing the voltage did
not affect the spacing between the beans much.

I'm not totally familiar with sign-tube power supplies.  Is it common for
jellybeans NOT to appear in sign tubes run at DC?  It is probable that the
use of an unfiltered DC supply would sweep the jellybean pattern back and
forth at 120Hz and make it invisible, while a high-freq supply would
reverse polarity so quickly that the pattern would not have time to
respond, and so would remain stable.  This would make it seem like AC
supplies work better than DC. If the AC hum was removed from the output of
a DC supply, I bet the jellybeans would appear. 

Here's something I haven't tried: if the frequency of the AC HV supply is
varied, does the spacing of the jellybeans change significantly?  If what
you say is true, then changing the supply frequency should change the
spacing, and by picking the correct frequency, any size of "jellybean"
could be created. 

But I suspect that it doesn't work this way.  Bill Parker's "Quite
Lightning" plasma sculpture shows about the same spacing of jellybeans as
seen when one waves a 60Hz sign tube around in the dark.  Yet his device
runs at a couple of megahertz. 

> This effect stems from plasmodial oscillations interfering with the frequency
> of the external electric field. 

And my previous explanation could be stated like this:

   This effect stems from plasmodial spatial oscillations interacting with
   the external electric field. 

3D ripples caused by the "electron wind."  Other suggestions for testing
which version is closer to correct? 

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