Re: Halogen lamps

[P3D John W Roberts <roberts@xxxxxxxxxxxxxxxxx>]

>Date: Thu, 2 Jan 1997 00:03:30 -0600
>From: P3D Bob Wier <wier@xxxxxxxxxxxxxxx>
>Subject: Halogen lamps

>...I ran across a site with a LOT of information on various
>lamp types (which is readable in large part without getting into
>too much detail). It can be found at..

>http://WWW.InterMarket.net:81/~don/light.html

>Here's part of what is said on halogens - please forgive the lousy
>formatting - it's a cut and paste from netscape to Eudora.
>====
>...Since the bulb is small and usually fairly strong, the bulb can be filled
>with gas to a higher pressure than usual. This slows down the
>evaporation of the filament. In addition, the small size of the
>bulb sometimes makes it economical to use premium fill gases such
>as krypton or xenon instead of the cheaper argon. 

Thanks - that explains an article I read last year, describing the work of
some technicians who maintain a large IMAX projector. The article explained
that the bulb is large, and filled with xenon under very high pressure, so
extreme care has to be taken in changing it. The technicians were pleased
that all the times a bulb had exploded, it had been in its armored enclosure, 
so nobody had been hurt. :-)

John R


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