"clifto" wrote in message
...
Sam Goldwasser wrote:
While the scenario of the bits of the filament shorting is possible with
some lamps (usually with long thin filaments, though unlikely with the
short filaments of halogen lamps), the more likely cause is the arc
resulting when the filament opens. This results in the arc moving
towards the filament supports, with a lower resistance than the filament
had originally, leading to a high current.

What I never figured out is how the arc is maintained for more than 1/120
of a second when there's no air around the arc to ionize.


There's argon or other inert gas in there, it ionizes just like the arc in a
discharge lamp.