Ionization of gasses

[Unsunghero]

Ok so I was bored at about 3am, and I fired up youtube, and I came across the match in the microwave trick. Supposedly this forms "plasma" or "ball lightning" by ionizing the carbon dioxide given off by the match.

Believe it or not that explanation took a long time to find, k3wlz mostly do that kind of stuff.

Anyways, this chain of thought led me to roguesci, as many things that explode or sear flesh do. I looked through the microwave ray gun patent and I thought about this, with a risk of sounding like a k3wl would it be possible to make a sort of "plasma gun" with this?

It could have a magnetron mounted on the back of it, along with a CO2 tank. The trigger would make 2 things happen, 1st it would activate the magnetron, secondly, it would send a high-pressure blast of CO2.

Some problems would be:
1. I'm not sure how hot the plasma would be, I just assumed that it's pretty hot.
2. It would disperse after a certain distance, though I'm sure this could be fixed.
3. I'm not sure which gasses could be ionized, the only thing I know about CO2 and different waves is that it absorbs infrared. Possibly something to do with it having a very linear structure?
More to come..

[megalomania]

This is certainly possible. There are already plasma torches for welding and plasmachemical devices that create interesting chemical reactions. I myself hope to build a plasmachemical reactor.

A plasma flame is extremly hot, in excess of 5000 degrees C or more depending on the material being ionized. The plasma will be sustained as long as the heat energy stays within it. Inside a domestic microwave the amount of plasma is very small compared to the vast quantity of relatively cold air. The plasma cools quickly. I suppose a magnetic field or some such trick of physics used in fusion research could work, but I doubt you could sustain a plasma flame far beyond the energy source used to initiate the flame. If you are thinking plasma flame thrower, this would require an extraordinarily powerful energy source. It would be far more efficient to use the microwave energy as is than to create a plasma with it.

I believe any material can be made into a plasma if it gets hot enough. Some gasses are more suitable than others. I don't think it is the CO2 in the burning candle that is the key to creating a plasma flame, but the microscopic carbon particles mixed with vaporized wax and water vapor. I am referring to a candle, which is what I have seen used in videos, but carbon particles are also present in matches.

[rangegal]

I remember reading that the candle is just there to burn up the oxygen in the chamber and create somewhat of a vacuum, the low pressure air (and smoke I guess) is then ionized by the microwaves. But I don't know anything about it, thats just what I read.

I read in popular science that plasma torches work simply by making an arch between 2 hafnium leads, which is then stretched out past the nozzle by a stream of CO2. I was intrigued how simple it sounded (although it's probably not that simple).

[Unsunghero]

So since I'm apparently in love with that oxy/acetylene idea in other explosives, that train of thought brought me back here. You say the tiny pieces of carbon in the fire are ionized, and this makes sense, acetylene has very visible pieces of carbon.

Maybe something like a glass tube with a magnetron and acetylene tank on the end. There has been the issue of range, I'll tell you using an oxy/acetylene torch I've hit the lever and people across the shop can feel the oxygen from it (when it's not on fire of course..). At a much higher PSI you would probably have a much longer range, a high pressure acetylene bottle (with porous material OC) spraying the acetylene into the microwave would be pretty intense I think. Basically to start it up you'd light the acetylene and get your fire going then hit a button or switch etc to activate the magnetron, the acetylene would be ionized as it left the glass tube.

Keep in mind a microwave uses something around I wanna say ~600 watts while a simple diesel generator will get you around 4kW.

Reading around on google, some guys apparently made one of these little direct microwave delivery systems, here is a quote to set up this video.

A phenomenon of fireball ejection from hot spots in solid materials(silicon, germanium, glass, ceramics, basalt, etc.) to the atmosphere is presented. The hot spot is created in the substrate material by the microwave-drill mechanism.The vaporized drop evolved from the hot spot is blown up, and forms a stable fireball buoyant in the air.

and the video of this: http://www.eng.tau.ac.il/~jerby/Fireball%20floating.wmv

This is with a 600 watt microwave, imagine 6kW? That's a very achievable number for a portable weapon, even on foot. Mentioned in the microwave oven gun patent someone suggested 50kW from the engine, I'd think more along the lines of 30kW. and we would be using a gas so it would be different, whether that's good or bad I'm not sure. I'm going to research it a little bit more (gotta get ahold of a copy of the poor man's ray gun) then start experimenting.

If the gas shot bursts at extremely high FPS like you would a bullet, I think being hit by a stream of plasma would hurt a little bit. I'm really tired, so I'm gonna go to bed and post more on this in the morning.

[Jacks Complete]

I'd take a look at your 7 day ban before you post again.

Plasma weapons don't work in air, simply because of the air. Too much air in the way either cools things right down, or simply disrupts the passage of the ionised air in the same way it stops gusts of air. A rolling vortex from a gas/air explosion in a 35 gallon drum can do some damage (think scaled-up Airzooka), if is was spinning a roll of hot plasma death at the same time, it would be a great one-shot weapon - possilby. In a bit of a wind, it would veer off, and your maximum range would be about 30 yards indoors, as a rough guess.

In space, plasma bolts would probably be great, until people started wearing electric/magnetic armour to send your shots back at you. You could easily accelerate them up towards a good fraction of the speed of light, and the temperatures would stay higher a lot longer in a vacuum. And no crosswinds, either!

I'm not sure 6kW could be considered "man portable" either. That's about 8 horsepower. And don't forget your losses in the system, either. A high powered 13A 240V microwave tops out at about 900W. It will be drawing at least 10A, so the input power is 2400+W, so about 40% efficiency, meaning you will need to generate 24kW for that output. That's really unlikely to be man portable. Just the sheer mass of copper to carry the 100A will be a killer, and have you ever felt how heavy even an air cooled microwave magnetron is?

Perhaps mounted it would work, but not on foot.

[megalomania]

I was at Best Buy today looking at the new microwaves. They now have a slew of 1350 watt models that do not weigh all that much. I have read in industrial magnetron literature that the energy efficiency of a magnetron decreases with rising wattage over a few thousand watts. I think any magnetron over 6000W costs 10x as much to make as a collection of lesser wattage magnetrons adding up to 6kW.

I once visited a url of a university website while I was looking for microwave plasma literature that had pictures of a plasma flame extending quite some distance. Alas, I can't find the site.

Attached is a journal article (likely an unsubmitted final draft since no publication headers are on this pdf) describing exactly what this thread specifies. The microwave plasma device pictured in this article uses several low wattage devices to achieve a total power of 4072 W, and it looks like a flame from 8-10 inches. There is a ruler in the background measuring the flame, but I can't see it too well.

From their conclusions: "The length of the plasma outside the waveguide depends on the microwave power level and the axial flow rate." This means the higher the wattage, and the faster the air flow of gas, the longer the flame.

To bring this back to why I was looking at microwave wattages today, I remember older systems with 600-800 watts with very heavy internals. I though my 1000W unit was quite powerful, but now there are 1350 W systems likely smaller, lighter, and cheaper than any magnetron manufactured today. I expect in the future, thanks to the economics of scale, for there to be 2000-3000 W magnetrons all over the place costing less than $10. A prototype 75 kW microwave plasma gun might be a gigantic and heavy affair today, but 15 years down the road it could be portable.

[Jacks Complete]

http://www.metacafe.com/watch/559847/smoke_ring_gun/ might be handy for this project. The vortex travels fairly well and retains stability. I know you can send smoke and smells a distance with them, perhaps a plasma could be sent the same way.

The easiest plasma might well be a flaming mix of chemicals.