Talk:Arc lamp

Title of the article

The term "arc lamp" seems a little generic to me; although it has a specific meaning in theatre parlance, it's also the generic term for a wide variety of lamp technologies.

Would anyone mind if we renamed this article to "Carbon arc lamp" and created a dab page at the old "Arc lamp" title?

Atlant 12:59, 16 May 2005 (UTC)

Re:Title of the article

I agree, and I probably should have read your comment before I edited the page and submitted my changes, but I'm new to this and I didn't see it. Anyway, how should lamps be classified? Is an "arc lamp" a general term for any lamp with an arc or is it just short for "carbon arc lamp"? It's not clear to me if an "arc lamp" is a type of "gas discharge lamp" or the other way around. I suppose the definitions are arbitrary. Is there a conventional way that these terms are defined or classified?

Mikiemike 19:32, 3 April 2006 (UTC)

In common usage the Arc lamp is always a Carbon arc lamp and the lamps you describe are Gas discharge lamps. There is duplication between the Arc lamp and Gas discharge lamp pages and it seems to me that they could be merged. As it stands, your edits seem to fit better on the Gas discharge lamp page, so if nobody likes the merge idea, perhaps the relevant edits could be moved to that page. Old Moonraker 23:51, 5 June 2006 (UTC)

Added header to Carbon Arc Lamp section and noted that this is the one most commonly meant. Old Moonraker 06:50, 20 July 2006 (UTC)

I think the page should be renamed Carbon Arc Lamp, and the information on Arc Lamps should be moved to Gas dischage lamps. MisterSheik 14:21, 28 August 2006 (UTC)

The "Carbon arc lamp" section is bigger than it used to be. Is it time to look at User:MisterSheik's suggestion again? --Old Moonraker (talk) 10:18, 18 November 2008 (UTC)

SOLAR RADIATION TEST

I need some help about solar radiation test IEC 60068-2-5 Which type of lamp to be used for this test??????? I need to perform SOLAR RADIATION TEST on Energy Meters

I need any specific type of lamp which can fulfill the test requirements Please give your suggestions ~~~~AAMIR~~~~

I think you'll find xenon arc lamps are usually used.

Atlant 15:09, 1 September 2006 (UTC)

Health Dangers?

I would think that there would be health dangers associated with electric arc lamps. The arc itself is extremely bright, and can cause Arc Eye. Would these old carbon arc lamps be powerful enough to cause this condition if looked directly at. Also, although minimal, electric arcs give off X-Rays. In a place with a high concentration of arc- lamps, could this be a problem?? --Jdedmond 20:26, 22 March 2007 (UTC)

Arc eye is not caused by the brightness of the arc but by the Ultra violet radiation such arcs give off. This radiation can be blocked by a simple glass sheet. DieSwartzPunkt (talk) 16:49, 12 July 2012 (UTC)

Carbon arcs should not be in direct view. A 1.6kW arc caused temporary blindness for around 40 minutes when a cover came away and it was viewed momentarily. High intensity and UV output. Even the lowest power carbon arcs cause problems with vision if in plain view, as I found at school. Tabby (talk) 05:28, 6 January 2008 (UTC)

Many hollywood film stars suffered permanent eye damage from the high intensity arc lamps that were required for technicolor cameras. DieSwartzPunkt (talk) 16:49, 12 July 2012 (UTC)

It's the same thing as Arc welding#Eye damage. 120.17.153.63 (talk) 06:46, 3 March 2018 (UTC)

Rewrite

This article needs to be rewritten by someone more familiar with writing and/or the English language. 97.113.109.15 (talk) 02:36, 6 February 2009 (UTC)

Fluorescent lamps

I think that these lamps are not actually "arc" lamps, they rather use glow discharge. I don't know if there's a strict boundary between low-power arc and hi-power glow discharge, but I think an arc is somewhat hot (temperature > 300C), and hi-power (>50Amps), which is not the case in fluorescent lights. —Preceding unsigned comment added by 77.45.233.7 (talk) 06:42, 21 August 2009 (UTC)

Oppose merge

An arc lamp and a gas discharge lamp are not the same thing. These articles must not be merged. The fundamental light producing mechanism is different. --Wtshymanski (talk) 22:44, 12 September 2009 (UTC)

Agree that the articles should not be merged. The article gas discharge lamp covers a wide variety of lamps, such as neon signs, flashtubes, metal halide lamps, and fluorescent lamps, to name a few. Each one is specialized enough to have its own article, but should be summarized in the parent article (Gas discharge lamp).

I disagree that the light producing mechanism is different, which is most assuredly ion recombination. I also disagree with the article's statement that only carbon arc lamps are called arc lamps. In my experience, a carbon arc lamp is called just that, "carbon arc lamp". Gas discharge arc lamps are usually just called arc lamps, although the name of the particular gas is often added, such as "argon arc lamp." Here is one good example it being used: High Performance Flash and Arc Lamps although I can find many others.

I think this article could definitely be expanded upon to include more info about the noble gas variety, such as I did with the flashtube article. I will work some more on this as my time frees up this winter. Zaereth (talk) 22:58, 16 September 2009 (UTC)

I was thinking a little less fundamentally than that - an arc lamp give light mostly from the glowing crater, whereas a discharge lamp gives light from the gas column ( or from the phosphors of a fluorescent lamp). --Wtshymanski (talk) 23:23, 16 September 2009 (UTC)

Hmmm, perhaps I'm misunderstanding your previous statement, as in, different from what? A xenon DC arc lamp is a type gas discharge lamp. I've never worked with carbon lamps before, but was under the assumption that the only difference was that the plasma medium is a non-metallic vapor (vaporized carbon). This opposed to the metallic vapor or noble gas of nearly all other types, such as mercury/argon in a fluorescent tube, (the phosphor coating is merely used to change the powerful UV into visible light, but the energy is all from gas ion emmision), sodium, etc.... But, like I said, beyond the noble, or, I guess I should say, natural state gas types, I really don't know that much. I may be wrong, but I think the key link between them is that an arc of any kind is an electrical discharge through some medium in a plasma state.

Personally, I think the parent article should be a mere summary of the different subarticles, and links should be provided in each section to the more detailed article, such as:

Main article: Flashtube

I think it helps keep articles more interesting for reader's who just want the jist of it, but keeps the very detailed information readily accessible to those who come looking. (I often use the articles Glass and Glass transition, or Dogfight and Air combat maneuvering as examples of why it's often best to summarize and separate.)Zaereth (talk) 00:18, 17 September 2009 (UTC)

Ahh, I see now. After doing a little googling, it appears that carbon arc starts out as an open air discharge, (mostly nitrogen), but quickly adds incandescense from the heated electrodes. (Turns out I was wrong. :-D ) Zaereth (talk) 00:37, 17 September 2009 (UTC)

My favorite Wikipedia moments are those in which I have to say "Hmm, that was right after all." YOu don't really know something until you write an article about it. --Wtshymanski (talk) 13:20, 17 September 2009 (UTC)

Well, as long as I learned something new then it made the day worth while. The term "arc lamp" is very common in lasers to describe what is basically a flashtube designed for continuous operation. Now I find there is a xenon arc lamp article as well. Unlike flashtubes, it is very common to use any of the noble gases in arc lamps. Like flashtubes or neon signs, the only difference between the gas types are the impedence characterisics and the output spectrum, so I can't see creating a separate article for each gas. Maybe it would be best to merge the first section of this article with the "xenon arc lamp" article, and simply rename it something like "Noble gas arc lamp." I could see the "Carbon arc lamp" article being a separate article, or maybe all these should be in one article simply called "Arc lamp."

While fluorescent and halide lights and such are technically a type of arc lamp, they are not normally referred to as such. The construction and operation methods are very different, so I think it's best to keep them in separate articles, all of these under the parent article "Gas discharge lamp." Any thoughts? Zaereth (talk) 17:02, 17 September 2009 (UTC)

Article is a bit confusing

The article, as it is written, seems to be a bit confused over the different types of lamps. In particular, the operation section describes the methods for operating metal-vapor lamps, but not for gas discharge lamps. The main difference being that metal-vapor lamps operate in a state of negative resistance, whereas gases found in DC arc lamps may go through a brief period of negative resistance during start-up, but operate under positive resistance. (eg: The voltage level controls the current level, not a ballast.)

Perhaps it would be better to divide this article into sections briefly summarizing the various types of lamps, such as carbon arc, metal-vapor (ie: sodium/mercury/halide), AC arc (neon signs), DC arc (laser and projector type arc lamps), and flashtubes. Once the "parent article" is created, we could link each section to its main article.

An article such as xenon arc lamp should be changed to include all of the gases, the way that the flashtube or neon sign articles do, since the only real differences between gases are the impedence charateristics and spectrum. Metal-vapor lamps should also be grouped together in a main article, perhaps branching out from there into each individual types, (since in these, construction and operation charactistics often differ).

Does anyone have any thoughts about organizing this information better? Zaereth (talk) 23:04, 20 July 2010 (UTC)

Yes, quite confusing since carbon rods are not gasses. Go ahead and try a reorganization. I'm thinking of moving the whole "Carbon Arc Lighting" sections, including the history section, to a separate article. Any comments on that? RedJ 17 (talk) 17:52, 23 October 2011 (UTC)

Some sort of re-structuring along these line was agreed abiut three years ago, but nothing came of it. Good luck! --Old Moonraker (talk) 05:57, 24 October 2011 (UTC)

I've been keeping this article on my radar for a few years now. I have plans to try to work on some restructuring this winter, but am still learning about the subject. I'm the most familiar with DC arc lamps and flashtubes.

One thing that I am finding out is that not all of these lamps can be considered arc lamps. Many of these lamp types, like fluorescent lamps and neon signs, are considered to be glow discharge lamps; the main difference being that a glow (gas) discharge lamp has a much lower current density and, therefore, higher impedance. This causes it to operate with a much higher voltage and low current. One characteristic of most glow discharge lamps is that they tend to operate at very low pressures.(From what I can tell, generally under 100 torr. but may be as high as 200 torr for "high pressure" sodium.)

Arc lamps, on the other hand, tend to operate with a very high current density and lower impedance. Therefore, when the current increases the voltage drops to a very low level. Arc lamps usually tend to operate with much higher pressures. (Usually between 500 to 3000 torr.)

Where to put carbon arc lamps is still confusing to me. It is definitely a type of arc lamp, in that the electrical discharge is an arc and not a glow discharge, but the light production appears to come mostly from the incandescent glow of the carbon rather than the plasma of the arc. I like the idea of creating a separate article for it, but keeping a short paragraph/section here briefly describing it, with a main article link. (Usually air pressure; ~ 760 torr.)

I'm still pretty busy with real life, though, and so I may not get to researching this properly for a few more months. Any help, though, is always welcome. Zaereth (talk) 19:32, 24 October 2011 (UTC)

Fluorescent lamps operate with an arc discharge; the trick is to look at the V/I characteristic, if the terminal voltage varies only a little with change in current, it's a glow discharge, if the voltage is steeply declining as current increases, it's an arc. A neon pilot lamp like an NE-2 is a glow discharge, and will be destroyed if you let it arc. --Wtshymanski (talk) 04:17, 27 October 2011 (UTC)

Yes, I'm just finding that out. I was just looking through the books Low temperature plasmas and Introduction to plasma technologies. I was apparently confusing cold-cathode fluorescent lamps (CCFLs) with regular fluorescent lamps. Apparently, there are two types of glow discharge lamps. Lamps such as nixie tubes produce a negative glow surrounding the cathode. Neon signs produce a positive column with a large dark space near the cathode. (When operated with AC, this positive column altenates, and so no dark space is readily visible.) Many gas lasers use the positive glow to excite the medium past threshold. The main difference does not appear to be pressure, but, at least for positive glows, such as neon signs and CCFLs, the diameter is relatively small while the length is fairly long. Of course, I'm still reading up on this and will continue to study it until I feel I have sufficient knowledge to begin making improvements. I'm probably going to start with the xenon arc lamp article, as these are the types of arc lamps I am most familier with. Figuring out exactly how to organize everything is proving to be a daunting task. Zaereth (talk) 07:51, 27 October 2011 (UTC)

Happy editing. All the articles on arcs and gas discharges want to be looked at carefully, and you can't go too far wrong if you have good references at hand. --Wtshymanski (talk) 13:34, 27 October 2011 (UTC)

Thanks, but I'm in no hurry. I often prefer to share my confusion with the world on the talk pages before making any major changes. I find this type of dialogue to be very helpful.

The book Lighting control-technology and applications gives a list of the various lamps that are normally classified as "arc lamps." These include DC Arc lamps (xenon, krypton, argon or mercury-xenon}, low pressure mercury vapor, (including regular fluorescent and compact fluorescent), high-pressure mercury vapor, low-pressure sodium, high-pressure sodium, and metal halides. It also describes some specialty lamps as having an arc, although they are not technically classified as arc lamps. These include induction lamps and flashtubes. Carbon-arc lamps are not discussed in this particular book, but of course, those are arc lamps as well.

Of these lamp types, only DC arc lamps and carbon-arc lamps appear to be commonly referred to as simply "arc lamps." I don't know what type of discharge flat lamps or other specialty lighting uses.

I think it may be worth making the gas-discharge lamp article into a parent article which briefly describes both glow discharge and arc lamps, with "main article" links to each. While a subordinate of the gas-discharge article, this arc lamp article could then be a parent article, briefly describing the various types of arc lamps, with main-article links to each one. (This would mean placing carbon-arc lamps into it's own article and leaving only a short description here, and renaming the xenon arc lamp article to DC arc lamp, so it can cover all types of gases.) That might possibly help to get things organized, to make information easier to find.

An alternative may be to leave the gas-discharge lamp article as the parent article for everything, merge the xenon arc lamp article with this one, and let this article describe only those lamps commonly referred to as arc lamps. Zaereth (talk) 23:57, 28 October 2011 (UTC)

Cold restrike

The article mentions "cold restrike" lamps which can't start when they aren't cooled down. That's very curious but the article doesn't explain why. Why? Also, is this why my home projector puts its fan on full blast after shutting off the lamp? Is it trying to get the bulb cold fast so it can be restarted ASAP? —Ben FrantzDale (talk) 22:56, 15 February 2012 (UTC)

That's a good question. I've never heard of lamps being designated as hot or cold restrike, (although the list of things-I've-never-heard-of could fill the encyclopedia Wikipedia). These terms are used often when talking about metal-vapor lamps; usually in terms of hot and cold restrike times. (ie: 2 minutes cold versus 10 minutes hot for a mercury bulb.) I know that most metal-vapor lamps can not restrike when hot. Striking is done with high-voltage, low-current power through the gas, until the solid or liquid metal vaporizes, at which point the main-driving current takes over. I'm also not sure why your projector fan would speed-up. If your arc lamp is mercury-xenon, then it may need extra cooling to quickly restrike. If it is xenon only, then temperture shouldn't affect restriking. It may simply be that the fan recieves a boost in voltage when the lamp is no longer drawing power. Someone else might be able to come along and give you a more informed answer. Zaereth (talk) 00:38, 16 February 2012 (UTC)

FWIW, metal-halide lamp mentions "restrike", suggesting that hot restrike requires a higher voltage ("Pulse-start metal-halide lamps don't contain a starting electrode, but they require an ignitor to generate a high-voltage (1–5 kV on cold strike, over 30 kV on hot restrike) pulse to start the arc."). I haven't studied why. As for the projector, I'm quite sure it's by design. It won't even let you turn the bulb back on while it's in the cool-down period. That said, being impatient I have unplugged it (causing it to forget its state), plugged it back in, and turned it on with no apparent issues. —Ben FrantzDale (talk) 14:30, 16 February 2012 (UTC)

The usual barrier to restriking is that as the lamp heats up, the internal pressure rises, effectively increasing the strike voltage. Thus the strike circuit cannot restrike the lamp until the internal pressure has dropped to the point where the strike voltage actually can cause the arc to strike. DieSwartzPunkt (talk) 16:53, 12 July 2012 (UTC)

Erroneous sentence in Operation section

AkariAkaori discovered this erroneous sentence in the "Operation" section: "The tips of the carbon rods are heated to incandescence, creating light". As he pointed out, the arc produces the light, not the electrodes. I corrected it. Thanks AkariAkaori. --Chetvorno^TALK 07:52, 23 November 2014 (UTC)

A lot of other sources seem to claim it's incandescence from the rods, but since the colour temperature usually exceeds the sublimation point of graphite I doubt the rods would last a second if that were the case; and the Tungsten electrodes in Xenon lamps ould certainly melt, yet they don't --AkariAkaori (talk) 23:26, 28 November 2014 (UTC)

Actually, it is correct that the visible light produced is from incandescence. The carbon vapor produces a strong line at 250 nm and a very intense, very broad line at 389 nm, but this is barely visible as a purple glow at the edge of the visual spectrum. (It give great sunburns, though.)The positive electrode, however, is heated to around 7600 degrees F (far surpassing the melting point of any metal) which is approaching the melting point of carbon. Because the electrode can be heated much higher than tungsten, the spectrum emitted is much closer to actual sunlight than a normal incandescent lamp. However, because they are typically not enclosed (open flame), they emit a huge amount of IR, getting more intense all the way past 3000 nm. This is unlike the sun, in which most long and short-wave radiation is absorbed by the atmosphere, or an incandescent lamp where it is absorbed by the glass. The lamps are usually brightest if the electrodes are placed at right angles to each other, with the positive electrode facing outward.

In a metal-electrode lamp, light is usually produced by a gas. The tungsten doesn't provide the resistance that carbon does, so there is actually very little heating at the anode. In this case, it's the cathode that takes nearly all of the damage, due to bombardment from positively-ionized atoms. Zaereth (talk) 21:14, 31 August 2015 (UTC)

How bright are carbon arc lamps

Historically they were sometimes called the 'indivisible light' (eg Disenchanted night... p56) because they had a minimum brightness - but how bright are they ?
... p55 says "thousands of candle powers". - Rod57 (talk) 12:28, 31 August 2015 (UTC)

A_Dictionary_of_Electrical_Words_Terms_and_Phrases Vol 2. 1902 p568 says a 10 Amp, 45 Volt arc is 2000 candle power. - Rod57 (talk) 16:38, 31 August 2015 (UTC)

According to Safety with Lasers and Other Optical Sources: A Comprehensive Handbook (2013) anywhere from 150 to 150000 candelas per square centimeter. Zaereth (talk) 01:52, 1 September 2015 (UTC)

Need more history

The first carbon arcs used DC power from voltaic batteries - light mainly comes from pit on positive anode. See the 1902 ref above p568
Carbon arcs drove the development of early dynamos and AC generators - need a more detailed timeline. Could say more about the different types of early carbon arc, and their regulators. - Rod57 (talk) 16:48, 31 August 2015 (UTC)

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Citation within Carbon-arc lighting in the U.S.

Within the section "Carbon-arc lighting in the U.S." there is a source cited that spills over into the article itself instead of going under references. Should be a minor structure fix with the sources. Dalmationrotary (talk) 10:18, 11 November 2023 (UTC)

Fixed. It was a simple matter of adding some ref tags. Zaereth (talk) 22:37, 14 November 2023 (UTC)