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Hello Everyone,

  This is my first email to this list. I apologize that this is not
exactly related to microscopy, but this seems to be the largest
knowledge base about mercury vapor lamps that I have been able to
find on the internet.
  We are using an HBO 103W bulb for our Schlieren imaging system for
supersonic flow visualization. The old setup used an OSRAM 200W/2
bulb with a lamp housing and lens (J. Unertl Optical Co.) and a
power supply from Robert W. Gates & co.  The equipment must be at
least 30 years old, if not 50 years. Recently the power supply
stopped working, and we purchased a Nikon C-SHP1 power supply. We
hooked up the power supply to the old housing (making certain
modifications), and used an HBO103W bulb which worked fantastically
for about 30 hours, having been turned off and on maybe 10 times.
The last time I tried to light it, the "Lamp Ready" light flickered
for 1 or 2 seconds and then went off. Examining the lamp, it did not
explode, but the inside of the glass is covered with mercury, so
that the electrodes are not even visible. I did not even try to
relight the bulb, I just assumed it was ruined.

I think that the bulb has probably failed from the modifications
that we made to the connections in the housing. The first
modification was that the mount for the bottom of the bulb had to
be made smaller because of the smaller diameter of the 103Wbulb.
This we did by using a small sleeve of copper inserted into
whatever metal material the existing mount was, possibly bronze.
After the bulb stopped working, the inside of the copper sleeve is
tinged pink, compared to the outside.

 For the top bulb mount, the old style bulb we were using had a
screw on it, and was attached to a flexible wire protected by
ceramic beads. The new style does not have a screw, so we made
another sleeve out of copper with a screw to tighten. The flexible
wiring with ceramic is still used to account for thermal expansion.
After running, the top copper mount is now dark gray-colored
(probably oxide), but this can be scratched off.

One other thing I noticed before the bulb would not light was that
there appeared to be some small bubbles inside of the bulb near the
bottom electrode after I had run it a few times.

I appreciate people taking the time to help me on this, and I intend
on attempting to contact OSRAM regarding this matter, but this
seemed like a good place to look for assistance.

Thanks,
Andrew O'Grady

-- 
Andrew M. O'Grady
212-854-7306
PhD Candidate
Mechanical Engineering Department
Columbia University
Mudd Building
500 West 120th Street
New York, NY 10027 USA