We are going to make plasma, the fourth state of matter after solid, liquid, and gas. I have seen vast machines use plasma etching and vapor deposition when touring LCD factories making TVs and computer displays, but I wasn't up on the science of it and didn't fully understand that part of it. So I have wanted to better understand the states of matter and their transitions. In math and science and computer programming, the diagram below is known as a state machine, and may be used to design a vending machine or calculator for example. In this case we are mapping out the known states and transitions of matter. I assume by now you are generally familiar with melting, freezing, boiling (vaporizing), and condensing (like fog or dew). We talked about sublimation in the cloud chamber experiment when frozen carbon dioxide went directly to a gas without passing Go and collecting $200. Here is the diagram which I labored over for many hours with precision tools:
Not everyone is familiar with plasma. You may have heard of plasma televisions. You definitely know the glow of neon lights and bright flash of lightning. The sun and other stars contain plasma. You have definitely seen it but likely did not process it as a fourth state of matter. When a neutral gas is superheated it can change into ions (atoms with electrons removed) and free electrons, which is basically a conductive substance that can be controlled with magnetism and electricity. The formation of plasma is called ionization. When it cools back to a more stable gas state, that is known as deionization.
Trivia: some scientists suspect that plasma is the most abundant form of matter in the universe. Nobody really knows.
More trivia: St. Elmo's Fire is a glob of plasma that hangs about occasionally and is known to pilots and mariners.
Thanks to a video from NileRed, I decided to make my own plasma in the microwave. My wife would not be happy if I destroyed the microwave or burned the house down, so I went for 'small but visible' plasma using two grapes which she had just bought. There are other more impressive way to form big bright balls of it, but we will stick with grapes for now. I should say don't try this at home...
It has actually taken science awhile to explain grape plasma. Original theories were wrong. I'll try to explain very briefly what scientists currently say is happening. The grapes being full of mostly water absorb the microwaves and heat up quickly. Two of them very close to each other (touching in my example) form one single heat center in between the grapes. This spot get incredibly hot, so hot that it ionizes hot gasses escaping from the grapes. We see sparking much like metal in a microwave, and this is the plasma shooting its free electrons out like little bits of lightning.
In case anyone ignores my admonition, don't do this to the point that the grapes catch on fire. Thirty seconds on high is probably more than enough. Trust me, the grapes get really hot quickly. Be careful touching them after the experiment. Use a watch glass or similar dish to hold them. You can eat them if you want (for some reason this is a common question) but wait til they cool. Use a rotating plate as microwaves have hot and cold spots due to microwave superposition (just like our light being cancelled out in the bismuth posts). The physicist Faraday says you can cut a small hole in your microwave for better filming, but I don't think it is worth it. Don't let your dog eat the grapes, cold or hot. Yes, that is my dog reflected off of the microwave in the video, hoping to get food out of this somehow.
This is what the (very hot) grapes (with a little juice splatter) looked like when done. You can easily see the heat center where the plasma was generated.
Thanks for reading,
Paul
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