Re: Van de Graaff /Pelletron (fwd) Yet another incidental VDG system. (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 17 Jan 2004 00:45:51 -0500
From: David Speck <dave@xxxxxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Van de Graaff /Pelletron (fwd) Yet another incidental VDG
    system.

Many years ago in the Chem labs at Cornell, while walking through the
corridors late at night, (or was it early in the AM -- same
difference!), I noticed a blue flash come from an unoccupied lab.

The lab had an elaborate glass vacuum rack on the pump, and there was a
large clear glass mercury diffusion pump running on the system.  I
availed myself of my lab master key (working for the Chem instrument
shop had its perks!), and went in for a closer look.  I could see tiny
droplets of mercury condensing and running down the interior of the
pump.  About every 10 seconds, a pale blue discharge nearly 12" long
would flash through the center bore of the pump -- apparently the
pressure in the system was high enough to allow a luminous discharge in
the mercury vapor.  There was no other source of voltage connected to
the rack, so the flowing mercury vapor, or was it the droplets, were
carrying charge from one the of the pump to the other.  Definitely a
neat piece of serendipity.

Dave