🚀 go-pugleaf

In article <9NOV199215335294@reg.triumf.ca> solu@reg.triumf.ca (SOLUK, RICHARD)
writes:

>  The apparatus was a standard discharge tube, i.e. simply a glass tube with
>high voltage electrodes at either end.  The tube was initially evacuated and
>was allowed to slowly fill with gas.  As the pressure increased the expected
>fluorescence occurred, but rather then involve the entire gas volume it was
>confined to a band which formed at one electrode and then began to propagate
>down the length of the tube (as a function of pressure).  Additional bands
>appeared and followed the first keeping an equal spacing between bands.
>Finally five distinct bands were present which eventually stopped moving, 
>intensified and merged into a uniform discharge.  Note that the gas pressure
>was allowed to increase continuously throughout this process.
>
>  The question I have is what effect would account for physical structure in
>the discharge?  Why would a distinct band form rather then a discharge through
>the entire tube, or perhaps a number of equally spaced bands appearing
>simultaneously down the length of the tube?

Both phenomena occur. I don't know (in detail) why.

The phenomena of gas discharge tubes have been extensively studied and
described, and so far as I can recall there is much that is not understood
about them. They are quite beautiful to look at, but are currently (sorry) not
very fashionable to study. Therefore professional scientists (called
"researchers" by the media these days) devote little attention to them now.

One of my old teachers, the late Leonard B. Loeb, made them his life's work,
and you should consult your library for his book on the subject. Mostly you
will find descriptive information such as the common names for the phenomena,
like "Crookes' dark space".

Leigh