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Friday, November 30, 2007

Plasma is the fourth state of matter. There are are four commonly known states of matter: Plasma (which should arguably be the first, since it is the most common state of matter in the known universe), gas, liquid, and solid, and a handful of less commonly known states. A plasma is what you get when you raise the temperature of gaseous elements so high that the outer electrons can freely move from atom to atom. This makes a plasma highly conductive, and sensitive to electromagnetic fields. Our star isn't a big ball of gas, it's a big ball of plasma.

It's possible to create the stuff of stars in a regular microwave oven at home. All one needs is a way to start conduction in air (a.k.a. dielectric breakdown), and then the energy provided by the microwave magnetron will takeover, feeding enough energy to keep air in dielectric breakdown, or rather, in a plasma state. Beware! This might damage the microwave. Damaged microwaves might damage you. Beware!

I made a small non-powered device that would start an arc at low temperature. Here's the first video:


Once the video is loaded, go frame by frame back and forth - you'll see how fast the plasma takes off. The camera is going at 15fps. The plasma runs off to the top right of the microwave, where you can see the plasma change the colour to blue (in frame by frame) because of the energized outer electron shells of the caked on foodstuffs, just before it gets sucked into the vent.

For my next try, I set up a rickety little structure to hold a glass jar upside down over my plasma source. With the plasma rising so fast, I could trap it in a jar like a bubble of air in a tub of water. Here's the video:


The plain glass jar (think it was from grape jam or cheez whiz) lasted about five seconds before it broke from the heat. Then things caught on fire. (mental note: next time use pyrex)

I've since found out that this method emits a nonzero amount of toxic gases. This may be dangerous. Don't consider doing it - just don't do it. Remember - Danger! Death is bad. Even if it doesn't kill you, toxic gases are bad in any amount. Don't risk it.

Audio isn't included in these clips, but there was a loud 120Hz buzzing noise coming from the plasma. Either the magnetron had a 60Hz mains signal modulated into its microwave carrier (you don't need to filter it - you're just cooking food, not sending information), or the plasma field is reacting to the 60Hz radiated by the mains lines running through the house.

Either way, the whole experiment was fun, but that was before I read about the toxic gases.

Burton MacKenZie www.burtonmackenzie.com

p.s. these videos are not linkjacked. I am the original author.

p.p.s. I'm always fascinated with the google ads that are machine-selected for the sidebars of these diverse technical topics. They're often "howto" kind of links, but me clicking on them violates my ad contract with google, and I find I'm just too lazy to type in the URL by hand. If anybody finds anything related and interesting, let me know. I won't even get to see the topics until I post this.

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