When the bulb is "struck" a high voltage RF pulse is feed to the bulb. Because the RF voltage is an alternating current, both electrodes are being hurt. The ignition voltage is high enough to ionize the gas between the electrodes, and an arc forms between the gaps. Because the gap has already been broken down, the low voltage DC can cross the gap, and produce lots of light.

Any other questions

Josh

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"Film is made of silver, video is made of rust"
'nuf said

The anode is the positive electrode of the lamp. (The cathode is the negative.) Electrons come in through the anode and jump the gap toward the other electrode. The xenon gas gets excited and gives off light. It's kind of like a subatomic game of billiards.

Xenon is one of the noble gases. (Helium, Neon, Argon, Krypton and Xenon.) They are VERY stable atoms. They have all of their elecrons in their outer shell. (Think like the solar system... The sun is the nucleus and the planets are the electrons.) Since it's very hard to knock an electron out of place in an atom like that, noble gases don't react with other elements very easily.

So, here comes this electron jumping off the the cathode and "flying" though an atmosphere of xenon gas. A lot of those electons are bound to hit an atom of the gas. When it does, one of the electrons in the outer shell gets knocked away from it's "ground state" into a larger orbit. The electron doesn't like that and wants to go back to the way it was. When it snaps back to it's original place it gives off the extra energy in the form of a photon.

Now, imagine that a huge number of electrons (6.25 X 10^25) TIMES the number of amps your lamp burns at) jumping that gap every second. Put a like number of xenon molecules inside that glass envelope (hence, the reason there is so much pressure inside) and think about the number of little collisions there would be... and how many photons would be given off. We're talking GOZILLIONS!

The anode is just the "landing pad" for those electrons after they have made the jump. The reason it's larger than the other one is that they need a bigger target. After being bounced off a few zillion xenon atoms they aren't flying in a straight line anymore so they become spread out. Sort of like the way water comes out of a garden hose when you put it on fine spray.

The anode (and the cathode) are made of tungsten alloy because they need to be able to withstand the heat caused by the hundreds of culoumbs of electrons whizzing through them every second. Even then, they can't withstand that kind of tourture forever. Ever notice that the ends of the electrodes get rounded off after they have been used for a while? That's because some of the metal has been literally vaporized. When the glass in your xenon lamp starts getting dark grey or black, that's becasue the metal vaporized off the elecrodes has deposited itself there.

When enough of the metal has been eroded it's time to replace the lamp. Otherwise the blackening will block a lot of the light. I would bet that it would cause the glass to get hotter too and raise the chances that the glass will fail. When the electrodes get worn away they start operating inefficiently. It takes more and more energy to push them across the gap. The heat goes up and less and less light gets produced. Finally, the lamp will give out all together if you don't replace it. It it gets too bad, the glass will give way or else the ceramic seal on the end of the lamp will blow out.

or "POW!"

Sorry, I could not resist.

I don't think so. If that were true, xenon bulbs would require extensive labeling re: the radioactive materials, and used bulbs would be considered HAZMAT and require specialized (read expensive) disposal .

JJ

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"Film is made of silver, video is made of rust"
'nuf said

Isn't it only perception anyway? Electrons do their stuff and we just need a way to visualize them doing it.

Disposal of a spent Xenon Lamp normally should not cause too much of a problem. However, I know of a person who saved up a whole bunch of cathodes. When he pointed a Geiger Counter in it's direction and had it about a foot away from the pile of cathodes, it drove the Geiger Counter nuts!

In eny avent, I would not recommend the cathodes be carried around in your pocket.

I know this shit... Honest!

Just don't ever ask me to do something like, "Go to Maple Drive, turn right and stop at house number 1321"because I'll turn LEFT on Apple Drive and stop at house number 1231!

(Paul: After they go "Pbpthbpthbthp!" the projector goes "Wooga-Wooga!" )

About 10 minutes into the reel, a strange noise was emitted from that old Super that sounded like "WOOGA WOOGA! - CLINK - BLAM..CLUNK!" Then I heard the "WOOGA WOOGA" noise on the floor, followed by a "Plop!"

By the way, are you going to put "Pbpthbpthpthp" in your dictionary? When you finish your dictionary, can I get a copy?

Would anyone be interested in doing a similar thing with discarded xenon bulb anodes and donating the proceeds to the Rick Long Memorial Beer Fund?

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