Sunday, November 27, 2005

Weird Science: Plasma


Today’s exploration is with the fourth state of matter, not the stuff in your blood - both called plasma though.

And I couldn’t help talking about plasma today because I just found the plasma pulse rifle in Doom 3 - and what am I talking about now?

Um, nevermind. Let’s just recap the first three states of matter first.

The first state of matter is solid. Like hard metals. Simple.

The second state of matter is liquid. Like vodka or water. Simple.

The third state of matter is gas. Like, what our bodies create after a good bean meal, or what we breath. Let’s hope the two are not the same - phew!

Which brings us to the fourth state of matter which is plasma. Not so simple, but damn cool (actually very, very hot) and used by science fiction writers for decades. But, what is it in the real world, and how do you make it?

Well, to state it plainly, plasma is a ionized gas. What this means is that once a gas reaches a high enough temperature the atoms making up the gas actually break down and the electrons orbiting them break free. The superheated gas is now in a plasma state - the fourth state of matter. If all the electrons have broken free of their atoms it is considered fully ionized.

So when does this occur?

Well, when a gas reaches temperatures around 3,500 up to 15,000 degree Fahrenheit and higher is when - and that’s plenty hot enough to frag demons in Doom 3 . . .

Um, but plasma, despite science fiction’s use of it, is real and has practical applications other than the fictional plasma pulse rifles . . .

And it can be created in several ways too. The first is using ohmic heating which means passing an electrical charge through the gas to heat it. Another is magnetic compression (this sounds cool enough to be used in plasma pulse rifles . . .) Which is a method of using increasingly strong magnetic fields to compress the gas and thus heat it. And one final method (though there are still more) I will mention is subjecting the gas to shock waves to heat it up.

Okay, but what is it used for?

Some really neat "real" applications are florescent lights, etching substrates for electronic components, chemical reaction stimulation called plasma synthesis as well as laser tubes . . .

And I though to myself, how come if plasma is 3,500 degrees or hotter that florescent tubes don’t burn your fingers to a crisp when you touch them - they are actually less hot to the touch than regular incandescent bulbs?

Well the answer lies in the fact that the florescent tube does not approach such high temperatures because the plasma continuously collides with the walls of the tube thus cooling it.

Yeah, didn’t convince me either, but it’s true.

And I used "thus" twice in this article. Is there some kind of prize for that?

Now, off to collect some more cells for my plasma pulse rifle.

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