From: Wayde Allen (wallen@boulder.nist.gov)
Date: 05/05/00-11:17:01 AM Z
On Fri, 5 May 2000, Rod Fleming wrote:
> However, the source I'd want to investigate- if I was not happy with the
> sun, which admittedly we Scots don't see too much of- would be carbon arc.
> This is really heavy on UV and requires the application of a continuous
> voltage across the gap between two carbon electrodes (anybody have an old
> WW2 anti-aircraft searchlight unit around?) You'd have to mount it remotely
> because of the heat, and use a condenser system to collimate the light, and
> have very efficient cooling, but I'm pretty sure it would work all right. A
> basic version could be designed using a small hobby type arc welder -say 120
> to 150 amp- fitted with a carbon arc brazing attachment. Remember to wear
> plenty of sun screen......
I've often thought about modifying a welder's carbon arc as you suggest.
There are a couple messy problems though. The worst one being that these
generate a fair amount of smoke as the carbon rods burn up. I'd guess
that this is mostly CO2 and CO, but the welders rods are also usually
coated with what looks like a copper coating, so that would be in the
smoke too. You'd need a good ventilation system to handle these gases.
Another problem is that you need to continuously feed the rods into the
gap as they burn up. That means you either need to control the gap
spacing dynamically by hand or setup the mechanics to handle this for you.
Finally, the carbon arc also generates a lot of heat, but then again you
noted that too. It is used as a heating arc as opposed to a welding arc,
and this heat will need to be dissipated.
Yes, I think it should work. However, it does pose some interesting
engineering problems. I haven't looked at any of the old commercial
carbon arc plate burners, but I think if you are serious about this it
would be a good idea. After all, there is no particularly good reason to
reinvent the wheel.
- Wayde
(wallen@boulder.nist.gov)
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