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Re: NEON- more pinhole suckins...

John, 
you can recreate this on your bombarder if you're curious.  Keep lowering
the pressure (open stopcock short straight tube w/doublebacks) and you can
watch the arc stream apear to compress and then go straight out of the metal
shell.  It may then take less than a second to heat that section of glass
and it suck in just like that stack of glass you have.
Reminds me of a caller we had a year or so ago: this guy couldn't get red
tubes to last more than 6 months or so (and had had this problem for all of
the 3 or 4 years he had been in business (I have no idea how he managed that
long)).  We started asking him questions about his pumping process.  
When I started asking about monitoring the pressure in the tube with the
U-gauge he said he didn't have one.  Okay, how about the Torr gauge? Not one
of those either.  Okay, some kind of mercury gauge / whatever just some
gauge that he used to fill the tubes with neon?!?  Nope, didn't have
anything like that.
Well, how did he measure the gas in the tube?  He had a small neon unit with
electrodes sticking off the manifold which had a transformer attached to
it's electrodes.  After bombarding he would let the tube cool and then fill
with neon until the little (attached) tube lit red.
(I've seen setup used as a "high vacuun test light" before)
I tried this system myself and a red tube will light at maybe 2 or 3 mm.
Which was all the gas he was putting in his tubes.
True story.
Morgan 



>I've just gotten an entire load (approx 30 units) of clear-red repairs.
>About 80% of them have the proverbial "pinhole suckin" we talked about
>earlier.  This is a hole in the double back right where the electrode
>aims:
>
>              -----  <-------- here
>             |  _  |
>             | | | |
>             | | | |
>             | | | |
>             | |  -
>             | |
>             | |
>             | |
>
>On every one:  the suck in is indeed right where a bullet would land if
>fired from the trode shell.
>
>All are 15mm clear red.  Most around 5-7 feet.  I didn't make any of
>these, but they appear to be not that old (they're Eurocom 'trodes,
>glass is still clear and fresh, boots still intact, etc).
>
>There is more sputtering than I would expect for tubes of this age, so I
>am assuming that the fill may have been too low.
>
>What I'd always assumed from seeing these before is that the 'trode
>arced thru to the metal letter, or a piece of GTO.  After discussing
>this on the list several months ago, examining these units (and talking
>to the installers), I agree this is NOT what's happening.
>
>Anyway, I'm really interested in the electron bombardment theory (or is
>it a known fact?)  Why would electrons emit in such a narrow, focused
>beam? George Doll mentioned that Al Sklar wrote an article on pinhole
>suckins - does anyone know where I can find a copy?
>
>    -John
>
>