This is topic Xenon Bulb Inards in forum Film-Yak at Film-Tech Forum ARCHIVE.


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Posted by Paul Konen (Member # 41) on 03-12-2006, 01:41 PM:
 
Since we have opened the theatre, a couple of people have been saving the two pieces inside the bulb that create the arc.

Are these any special to save? Hazardous? Can someone shed some light on what these are made of?
 

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Posted by Scott Norwood (Member # 30) on 03-12-2006, 02:00 PM:
 
The anodes (postive ends) are made of tungsten. I believe that they may have some scrap-metal value, but I can't imagine that it's much, unless you have a 30-plex worth of bulbs or IMAX bulbs or something like that.
 

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Posted by Leo Enticknap (Member # 534) on 03-12-2006, 04:08 PM:
 
I've got one from an exploded bulb which I use as a paperweight.
 

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Posted by John Walsh (Member # 168) on 03-13-2006, 07:17 AM:
 
I had heard that the heavy cathode inside is slightly radioactive, at least on older bulbs.
 

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Posted by Alexander Smith (Member # 1769) on 03-13-2006, 08:25 AM:
 
I know someone who has access to a Geiger-Müller particle
counter. If I can arrange it, I'll take an old anode from
a 3kW Osram Xenon and see if it has any more radiation than
"background".

Alex.
 

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Posted by Cory Isemann (Member # 2517) on 03-13-2006, 08:39 AM:
 

quote: Alexander Smith

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I know someone who has access to a Geiger-Müller particle counter.

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quote:

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quote: Alexander Smith I know someone who has access to a Geiger-Müller particle counter.

Friends in high places...

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No, the lab technician at the local school. :-)

Alex.
 

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Posted by John Pytlak (Member # 331) on 03-13-2006, 12:25 PM:
 
Weren't small amounts of radioactive thorium sometimes used to improve ignition characteristics by enhancing electron emission?
 

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Posted by Leo Enticknap (Member # 534) on 03-13-2006, 01:25 PM:
 
Looks like my kids are going to be born with cloven hooves and two heads, then...
 

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Posted by Louis Bornwasser (Member # 3063) on 03-13-2006, 02:17 PM:
 
SMALL amounts!
 

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Posted by John Pytlak (Member # 331) on 03-13-2006, 03:48 PM:
 
Radioactive thorium was also used in vacuum tube cathodes and gas lantern mantles.
 

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Posted by Phil Hill (Member # 371) on 03-13-2006, 04:10 PM:
 
Actually that big and "heavy" electrode in a xenon lamp is the anode and is made of pure tungsten...it is not radioactive and does make a great paperweight.

The smaller, conical-shaped cathode is also made of tungsten but is "doped" with a small amount (about 2%) radioactive thorium to (as John noted) provide more free electrons and to make the arc start easier.

I wouldn't worry much about the small amount of thorium in a cathode unless you grind/machine it and inhale the dust. Same goes for inhaling welding fumes from electrodes made of thoriated tungsten...although now there are many different non-radioactive materials for welding electrodes.

I'd be more thinking about the radioactive americium in the bazillion ionization-chamber smoke detectors around that many of us sleep under.

I wont even mention the radioactive radon gas that seeps into many houses...
 

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Posted by Mark Gulbrandsen (Member # 72) on 03-13-2006, 07:15 PM:
 
Here is all the do-do on Thorium....... Its used in many surprising ways and it looks like it'll be around a VERY long time......

Thorium

Atomic Number: 90


Atomic Weight: 232.0381


Melting Point: 2023 K (1750°C or 3182°F)


Boiling Point: 5061 K (4788°C or 8650°F)


Density: 11.72 grams per cubic centimeter


Phase at Room Temperature: Solid


Element Classification: Metal


Radioactive



Period Number: 7 Group Number: none Group Name: Actinide


What's in a name? Named for the Scandinavian god of war, Thor.


Say what? Thorium is pronounced as THOR-i-em or as THO-ri-em.


History and Uses:
Thorium was discovered by Jöns Jacob Berzelius, a Swedish chemist, in 1828. He discovered it in a sample of a mineral that was given to him by the Reverend Has Morten Thrane Esmark, who suspected that it contained an unknown substance. Esmark's mineral is now known as thorite (ThSiO4). Thorium makes up about 0.0007% of the earth's crust and is primarily obtained from thorite, thorianite (ThO2) and monazite ((Ce, La, Th, Nd, Y)PO4).

Thorium is used as an alloying agent to improve magnesium's strength at high temperatures. Thorium is also used to coat tungsten filaments used in electronic devices, such at television sets. When bombarded with neutrons, thorium-232 becomes thorium-233, which eventually decays into uranium-233 through a series of beta decays. Uranium-233 is a fissionable material and can be used as a nuclear fuel.

Thorium oxide (ThO2), one of thorium's compounds, has many uses. It is primarily used in a type of lantern mantel known as a Welsbach mantle. This mantle, which also contains about 1% cerium oxide, glows with a bright white light when it is heated in a gas flame. Thorium oxide has a very high melting point, about 3300°C, and is used to make high temperature crucibles. Thorium oxide is also used to make glass with a high index of refraction that is used to make high quality camera lenses. Thorium oxide is used as a catalyst in the production of sulfuric acid (H2SO4), in the cracking of petroleum products and in the conversion of ammonia (NH3) to nitric acid (HNO3).

Thorium's most stable isotope, thorium-232, has a half-life of about 14,050,000,000 years. It decays into radium-228 through alpha decay or decays through spontaneous fission.


Estimated Crustal Abundance: 9.6 milligrams per kilogram

Estimated Oceanic Abundance: 1×10-6 milligrams per liter

Number of Stable Isotopes: 0 (View all isotope data)

Ionization Energy: 6.08 eV

Oxidation State: +4

Electron Shell Configuration: 1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d10
6s2 6p6 6d2
7s2
 

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Posted by Leo Enticknap (Member # 534) on 03-14-2006, 04:22 AM:
 

quote: Phil Hill

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I wouldn't worry much about the small amount of thorium in a cathode unless you grind/machine it and inhale the dust.

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You've obviously never heard of cobalt thorium G.

Cobalt thorium G has a radioactive halflife of ninety three years. If you take, say, fifty H-bombs in the hundred megaton range and jacket them with cobalt thorium G, when they are exploded they will produce a doomsday shroud. A lethal cloud of radioactivity which will encircle the earth for ninety three years!

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quote:

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I'd be more thinking about the radioactive americium in the bazillion ionization-chamber smoke detectors around that many of us sleep under. [Wink]

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Americium == Alpha radiation == yawn.

Alpha particles can be stopped by a sheet of paper.

"The alpha particles from the smoke detector do not themselves pose a health hazard, as they are absorbed in a few centimetres of air or by the structure of the detector." (src: http://www.uic.com.au/nip35.htm)
 

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Posted by Louis Bornwasser (Member # 3063) on 03-15-2006, 09:18 AM:
 
I think I'll just worry about being run down by a runaway locomotive! Louis
 

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Posted by Gerard S. Cohen (Member # 994) on 03-15-2006, 03:55 PM:
 
Since both anode and cathode are shaped like projectiles, I wonder if they are suitable calibers to fit rifle shell casings?
(If I remember correctly, the cathode is about the diameter of a .22, and the anode, a .45 caliber.)

Perhaps a reloading hobbyist might experiment. Since tungsten is a very hard metal, they might serve as armor-piercing bullets, though that hardness might damage the lands on a rifle barrel.

They might also be useful as balance-beam scale weights, for darkroom chemical measurement.

[ 03-16-2006, 11:45 AM: Message edited by: Gerard S. Cohen ]
 

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Posted by Phil Hill (Member # 371) on 03-15-2006, 11:49 PM:
 
Robert & Louis = BIG YAWN! Apparently yous didn't "get" my "wink"... DUH!

Gerard: Interesting, and provocative post.
 

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Posted by Monte L Fullmer (Member # 2797) on 03-16-2006, 04:33 AM:
 

quote: Phil Hill

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and does make a great paperweight.

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quote: Gerard S. Cohen

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(If I remember correctly, the cathode is about the diameter of a .22, and the anode, a .45 caliber.)

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Well the cathode on my 7kw's are 12mm so they'd almost fit a .50 cal Browning and the anode's are 25mm diameter.They should fit this quite nicely

That's what I call a nice weapon for self defense
 

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Posted by Monte L Fullmer (Member # 2797) on 03-17-2006, 03:08 AM:
 
..that would bring down a King Tiger II tank...
 

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Posted by Dave Macaulay (Member # 813) on 03-20-2006, 03:47 PM:
 
The half-life describes the time something takes to become half as radioactive. So your doomsday bomb radioactive cloud might still be lethal for hundreds of years, or just become annoying before the half-life has passed...
I have a tritium "lamp" that's still useably bright 2 half-lifes (25 years) after manufacture.
 

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Posted by Thomas King (Member # 2745) on 03-21-2006, 06:54 AM:
 
I was going to make a key fob out of our old electrode, but

a) it was bigger than I expected
b) I saw that episode of House.

Now it just kicks around my desk.

On a related note: how do people get rid of their bulbs? I derive great satisfaction from throwing them down a flight of steps.
 

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Posted by Randy Stankey (Member # 64) on 03-21-2006, 12:10 PM:
 
Mostly, I put them into the dumpster and turn on the compactor. It's fun to hear them go "POW!!" when they break. Any flying glass particles are contained inside the steel dumpster.

But, every once in a while, I like to take them out back, in the woods, prop them up on an old tree stump and shoot them with a .22 rifle!

It's a spectacular sight! Some day, I'm going to get a video of one as it bursts!
 

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Posted by Monte L Fullmer (Member # 2797) on 03-21-2006, 01:06 PM:
 
Yea, it's pretty cool seeing one explode without the shield. We use to toss them out and down to the pavement from up on the roof..pretty cool "hand genades" - seeing how much that quartz do fly in all directions when it's not contained.
 

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Posted by Alexander Smith (Member # 1769) on 03-24-2006, 01:22 PM:
 
A video of a xenon being shot! I can't wait... :-)

I think my fellow cow-orkers would like to see that also.

Alex.
 

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Posted by John Pytlak (Member # 331) on 03-24-2006, 09:02 PM:
 
I recall that NASA once had a xenon safety training film that showed a very large (15KW?) lamp being hit by a metal weight swinging in as a pendulum. The slow-motion explosion of the lamp with quartz flying in all directions was quite impressive! Does anyone recall this film, or know where a copy can be found today?
 

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Posted by Kyle Anderson (Member # 3504) on 03-28-2006, 09:30 PM:
 
Hmm... wouldn't it be even cooler if the lamp was lit at the time it was shot?
 

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Posted by Randy Stankey (Member # 64) on 03-28-2006, 11:31 PM:
 
The neat thing about shooting something with a small caliber round like a .22 is that it flies very fast and imparts very little of its energy into the target unless it is stopped by something harder and more massive than itself.

Thus, when a xenon lamp is shot with a .22 the slug, pretty much, blows right on through. The explosion isn't affected by the inertia of a falling weight. You get a nice radial explosion pattern.

When surveying the damage of an exploded 4,200 watt lamp I have found substantial chunks of glass, an inch in diameter, more than 20 feet away!

I think I should make an exploding xenon video.
I plan to put the camera behind a piece of 1/2" plywood with a plexiglass window in it. I will shoot from at least 50 yards away. That's safe enough. Besides, my rifle is sighted in for that distance.

I was thinking of putting a Styrofoam wig head next to the lamp when I blow it up just to show the potential for damage to a person.

How about I compare a 4,000 lamp's explosion to a 15K?
Anybody have any old lamps they want to see get blown up?
 

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