Hacker News Reader

Comment by ravenstine | Hacker News Reader

Add a drinking glass: https://www.youtube.com/watch?v=sYusDh0Sw3U

We used to do this with incandescent bulbs. I was never quite sure if it was safe (is it?!), but the microwave itself always seemed to survive ok.

Generally the bulb would explode, we presumed due to the heat causing internal pressure. Though at one point a bulb got really hot and melted a sort of bubble on the side. It seemed to provide enough space for the heated air so it never exploded and we could use it again and again.

You can make plasma with a partially evacuated sealed bottle, it’s basially how plasma chambers work and it’s a handy way to get plasma if you’re stuck.

You can use different gases in the bottle for different plasmas.

> it’s a handy way to get plasma if you’re stuck.

I'm finding it hard to imagine a situation where I desperately need to make plasma but I'll file this one away just in case. ;)

I’ve seen it used to treat cured PDMS elastomer and glass slides for bonding microfluidic devices (aligns OH groups to the surface to achieve a covalent bond between the PDMS and glass). Our plasma chamber was destroyed by a student so I used a corona discharge tool, or a cattle prod as it’s better known. Was tempted to buy a cheap microwave tho...

Solid glass is transparent to microwaves, but molten glass absorbs them pretty well. So, if you can get a piece of glass hot enough, the microwaves will be able to keep it hot.

And melt it!

http://www.metacafe.com/watch/1004040/melt_a_frickn_beer_bot...

Incandescent bulbs are vacuumed inside (that's why they make a popping sound when they shatter), so it was probably the plasma melting the glass.

What in the world... that's awesome.

I know what I'm doing tomorrow with our old microwave.

If you have any extra CDs around, those are entertaining (though I'd do it outside for the smoke).

Ha! Talk about your theory to practice experiments. The grape becomes a plasma, and the glass contains it - brilliant!!!

That does look like descriptions of ball lightning. I wonder if the mechanism is similar.

Hm... confined plasma... could this be used to start a fusion process?

"After decades of research and hundreds of billions of dollars spent, a breakthrough in fusion reactors is made thanks to a youtube video of a grape in a microwave."

Haha, why not? ;) At least someone more knowledgable than me could explain why this is so obviously a silly idea.

Not a physicist, I'll take a crack at it. Fusion needs two things: 1. plasma (easy part) 2. pressure (hard part) - this is normally referred to as confinement, which is misleading. What you're trying to do is squeeze the plasma into a really small volume, which is like squeezing water in your hands into a perfect compressed sphere. Try it.

Stars do it easily, because the confinement / pressure is provided by immense gravity which very conveniently works to compress a huge load of gas into a point space.

Reply on news.ycombinator.com