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Topic: Xenon Bulb Inards

Paul Konen
Jedi Master Film Handler

Posts: 981
From: Frisco, TX. (North of Dallas)
Registered: Jun 99

posted 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 [Roll Eyes]

on what these are made of?

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 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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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 03-12-2006 04:08 PM

I've got one from an exploded bulb which I use as a paperweight.

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 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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Alexander Smith
Expert Film Handler

Posts: 128
From: Walney Island, Barrow-in-Furness, Cumbria.
Registered: Jun 2003

posted 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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Cory Isemann
Jedi Master Film Handler

Posts: 500
From: White Plains, MD, USA
Registered: Jun 2004

posted 03-13-2006 08:39 AM

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

Friends in high places...

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Alexander Smith
Expert Film Handler

Posts: 128
From: Walney Island, Barrow-in-Furness, Cumbria.
Registered: Jun 2003

posted 03-13-2006 12:02 PM

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

Friends in high places...

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

Alex.

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John Pytlak
Film God

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

posted 03-13-2006 12:25 PM

Weren't small amounts of radioactive thorium sometimes used to improve ignition characteristics by enhancing electron emission? [Confused]

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 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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Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 03-13-2006 02:17 PM

SMALL amounts!

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John Pytlak
Film God

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

posted 03-13-2006 03:48 PM

Radioactive thorium was also used in vacuum tube cathodes and gas lantern mantles.

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Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000

posted 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. [beer]

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. [Wink]

I wont even mention the radioactive radon gas that seeps into many houses... [Eek!]

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 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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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 03-14-2006 04:22 AM

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

I can think of some, more, err, exciting solids to grind up and then inhale - not that I'm speaking from personal experience, of course!

Incidentally, uranium sulphate was used as a tinting dye for silent prints. A friend at the BFI said that some 1920s elements can get a Geiger counter quite lively.

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William Hooper
Phenomenal Film Handler

Posts: 1879
From: Mobile, AL USA
Registered: Jun 99

posted 03-15-2006 03:22 AM

quote:

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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