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Topic: How Hot Is It?

Bill Enos
Film God

Posts: 2081
From: Richmond, Virginia, USA
Registered: Apr 2000

posted 04-10-2001 03:06 PM

What is the temperature F of the plasma spot in a xenox lamp at rated current?

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 04-10-2001 03:54 PM

One of the lamp manufacturers should be able to tell you. AFAIK, since most of the light comes from that plasma, it is probably close to 5400 Degrees Kelvin (9,260 F.). Pretty hot!!!

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 04-10-2001 04:27 PM

I was told years ago by a Hanovia Engineer that it is so hot that it has never actually been observed.
Mark @ GTS

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Jerry Chase
Phenomenal Film Handler

Posts: 1068
From: Margate, FL, USA
Registered: Nov 2000

posted 04-10-2001 05:32 PM

I think Mark is right. A xenon plasma ball is not a black body radiator. It has a burp in the spectra around 900nM and the light is from the plasma which, on a simplistic level, uses xenon as a catalyst to convert electrons into photons. The generation of light from plasma involves the stripping of gas atoms into positive and negative ions, energy states, etc. Measuring the temperature of the exact tiny areas giving off a proton would be incredibly difficult. Measuring the overall temperature of the ball would give a lower temperature, but that would be inexact, because of the gas currents that constantly sweep heated gas and ions away, and refresh it with colder gas. Plasma is a whole different state of matter, and from what little I understand, temperature doesn't have the same relevancy that it does in solids, liquids, or gasses.

Assuming zero efficiency (all the power being converted to heat) and straight black body radiation, you could guesstimate a minimum temperature mathematically. You know the power being applied and you know the dimensions of the ball. You also know the cfm of the exhaust and the delta T between room air and exhaust air. I'll bet Evans could do the math in a flash.

Here is a link to Don Klipstein's page on xenon:
http://www.misty.com/people/don/shortarc.html

Don is a usenet regular on some groups and is a brain on a number of subjects, especially lighting.

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