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Welsbach Mantle Physics? [INDEX: Technical]

Welsbach Mantle Physics? by William Buchman (ar465@lafn.org)
Posted: September 14, 1998 @ 19:11.
I am not a lamp collector, but I am interested in the physics of mantles. Some of my friends have such interest as well. The last time I tried to get such information, my conclusion was that it is not well understood. Any information pointing toward such understanding would be greatly appreciated. I believe that part of the performance come about because the mantle is a selective radiator. That is, it does not look like a black body except possibly at visible wavelengths. Thus, it reaches a higher temperature than a metal mesh might. Another possibility that I have seen describedd is that there is a phenomenon called candeleluminescence (spelling?) that uses a non thermal mechanism for producing light. William Buchman

On September 14, 1998 @ 20:27, Fil graff, Guild Secretary (fgraff@comcast.net) wrote:
William: I'm referring this to our mantle expert, John Claypole...he should answer right here. :: Fil ::
On September 15, 1998 @ 12:43, Heinz Baumann (baumann@sc3101.med.buffalo.edu) wrote:
There is nothing particularly mystic about incandescence. Here is a brief description: Incandescent light (or luminescence) is produced when an object is heated until it glows. To emit white light, an object must be heated to at least 1,341°F (or 727°Celsius or 1000 Kelvin). Luminescence is generated as part of a process in which heating excites atoms (like metal in electric filament bulbs) ions (like calcium salts in lime light or thorium oxide in the incandescent mantle) or molecules (wood chips in the fire place) into higher energy states and this energy is given off again as visible light when returning to the ground energy state.
On September 28, 1998 @ 15:17, Fil Graff (fgraff@comcast.net) wrote:
The following was sent to me by a lamper friend, evidently from an Internet chat group. I guess it is Mr. Buchman answering his own question. Phyzzicks is way over my head, so I don't really know what's being said here, but for you who do...[d'ja ever think kerosene lamps and lasers would get equal billing in an article?]

From billyfish@aol.com (BillyFish)
Organization AOL http://www.aol.com
Date 18 Sep 1998 23:40:22 GMT
Newsgroups sci.optics

I went to the Loyola University Library. After a bit of searching, I found a fairly extensive article on the Welsbach mantle in Mellor's Treatise on Inorganic and Theoretical Chemistry. At the time of the writing, (1930's?) the physics had not been pinned down. Gas mantles no longer command much scientific interest because the economic ramifications of mantle use are rather limited. At one time gas mantles were at the heart of lighthouse operation.

Many materials were tried as a host for the colored rare earths, but thorium oxide (quadrivalent Th) was the best. My guess is that it was the most transparent at near infrared because it had a high Debye temperature. Thoria had mechanical and other properties that also helped. Cerium (quadrivalent) gave the best optical performance. Performance reached a sharp peak at 1% concentration. This was probably the best concentration for visible emission without excessive infrared emission. Other rare earths also affected color and efficiency. Extensive work was done to track down the most efficient combination. Vitrification of the host was bad. Maybe it affected the spectral lines and cross-section of the Ce ions.

There was controversy on how the mantle actually worked that probably exists till today. It appears that knowledge of rare earth optical properties was not as great as it is now. A number of people thought that performance could be explained entirely by selective radiation. Others thought that there had to be something else. This was fueled by the fact that the thoria acted as a catalyst for the oxidation of hydrogen into water. The temperature of the reaction threshold was reduced from 650C to 315C There was some argument about oxidation-recuction oscillation of ceria particles which caused small scale temperature elevations that could not be detected with thermocouples. Thae big guns Nernst and Le Chatelier went for the selective radiation theory alone.

The reason I went off on this was because I vaguely remember seeing a report on more recent work on candoluminescence. I ran across this when looking for more efficient ways of pumping lasers. With diode lasers now available for such application, there seems to be little incentive to find better chemical ways to beat black body radiation by a relatively small factor. Nevertheless, I find the interaction of transparent hosts with high Debye temperatures, rare earth optical properties, and quantum thermal effects to be of great curiosity.
William Buchman
- On September 29, 1998 @ 00:34, English Archbishop (Lightinter@aol.com) wrote:
  Gentlemen - Here we have a prime example of a knowledge box - why do lamp collectors have to be bothered with such people? Lighthouses were fired by oil and seldom by gas with burners such as the Kitson and the Tilley. Get into the real world and dont pester genuine lamp enthusiasts again. English Archbishop.