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Rail Guns Closer to Reality
emtboy9 writes "Yahoo News is reporting that scientists at Sandia National Labs have created a magnetic pulse gun (rail gun) that can accelerate small aluminum plates at 34 kilometers per second, faster than the Earth travels through space.
The accelerated plates strike a target after traveling only five millimeters, or less than a quarter-inch. The impact generates a shock wave -- in some cases, reaching 15 million times atmospheric pressure -- that passes through the target material turning matter into various states almost instantly (solids into liquids, liquids into gas, and even gas into plasma)."
Call it a "rail launcher" and fire satellite payloads into orbit. Of course you'll have to slow down the velocity or the payload will ionize in the atmosphere upon launch. Rail launchers are more practical in a vacuum, as there is no atmosphere to interfere with hypervolocity launches. Perfect for chunking mined ore from the Moon to Earth?
I'll bet this railgun on fires a few millimeters because they have problems with longer magnetic "barrels" exploding from the shockwave produced by an object moving "at the speed the Earth moves through space".
"As for the future, your task is not to foresee it, but to enable it." - Antoine de Saint-Exupery
However -- rail guns are on the cusp of military viability. The University of Texas at Austin's Institute of Advanced Technology got 10 million dollars to develop viable rail guns. Just a month ago Janes reported that a prototype of the military rail gun had been tested, and that it was nearing viability.
That article really made me wish I had a Jane's subscription. Apparently, the limiting factor is the size of the capacitor -- if they can get this down than naval applications within a few years are plausible.Incidentally, a fun game, if you're ever bored, is to imagine what would happen to the human body if one were to hold and fire a rail gun (even a wimpy one that shot at a mere 1,600m/s and not at "near the speed of light"), and the law of conservation of momentum actually worked. Really! Try at parties!
Fond wishes,
Moiche
This is the huge tidbit that I haven't really seen discussed: "That's 50 times faster than a rifle bullet, and three times the velocity needed to escape Earth's gravitational field." A rail gun, of sufficient capacity to catapult raw materials into orbit, would be a gigantic breakthrough for the whole planet.
The Z machine (and it's earlier configuration called PBFA 2) have been on Sandia for a long time.
As said above, it's not a rail gun. It's not really even particularly useful for rail gun research.
What it's for is to put small amounts of matter at tremendous temperatures and pressures.
There are a lot of reasons to want to do this. Some of it is just basic research. i.e. What happens to matter and the laws governing it at these extreme conditions?
Another application is fusion power research. You can compress deuturium and tritium to the point they will fuse in this machine. Though it's not made to generate power, you can learn about the details of the fusion reaction.
That said, the main reason why this machine was built was indeed for military research. But even that is in a grey area. The US hasn't conducted a nuclear test detonation in quite some time. The reason it was able to do this is that computer simulations and other methods got good enough that they were able to be used instead of actually setting off a thermonuclear or nuclear device. Indeed, many of the Department of Energy's most powerful computers were created specifically to do that sort simulation (ASCII White, IIRC, for example).
When running computer simulations, you have to have some way of calibrating the simulation and checking that it's getting the right answer.
In the case of a supercomputer run simulating a car crash, you can validate it by conducting crash tests, and seeing how closely it agrees with them. Wrecking a few of a given car model is acceptable in return for it.
But, when simulating nuclear weapons, you would often run into cases where to validate the code, you'd, at first glance, have to set one off. The conditions in a nuclear blast are so extreme, that it's difficult to put matter into that sort of state. If you're trying to maintain a test moratorium, that kinda undermines the whole idea.
That's a big reason PBFA 2 and the follow on Z machine were made. They let DOE check the computer simulations and do basic research that would otherwise require nuclear testing. One of the biggest areas of interest is what happens when the materials in a bomb age. A lot of those weapons are getting quite old.
They have many other basic research uses, but a big one is making it possible to keep the nuclear test moratorium.
So, it's grey area. On the one hand, it's used for weapon research. On the other, it helps keep the test moratorium. It also has a lot of basic research uses. So, just like a supercomputer, you have to make your own decision about whether it, on the whole is a good or bad thing.
Accelrates at 34 km/s?? I thought that was a velocity. If .5 (at^2) = .005 m
And at = 34000 m/s
...then that makes the time about 3e-7 s. That would be something like 11.8 billion g's.
Not bad. Even for such a small projectile, that's an impressive impulse.
-ex
Actually there's no military applications for it really. It's to ionise matter that's extremely close to the (uhem) "gun", pretty much nothing else. It's not a railgun. You won't be able to do some sniping with it no.
For every force there is an equal and opposite reaction. Making something go from 0 to 34 in the distance of a gun must produce one major recoil.
Now I foresee a human-carried model! Shoulder rocket launchers let the rocket go on its own - no recoil but don't stand behind the tube. Well, let's replace the burning rocket fuel with a rail gun. The rail shoots out the back in slow motion and the payload goes out the front much much faster. Right? But we're talking magnetic fields at work so....the rail can be curved!! What does that mean?
North and south. Poles that is - double barrel shotgun. As long as both barrels shoot at once one side balances the other as long as the force should cancel at the back end.
Just in case some entrepreneur wants to build one now, remember Equal and Opposite. The rail has to be flexed. In other words, think sawed off shotgun, and even think crossbow. The rail has to be horizontal for the most part until the ends where the ammo is turned by the electromagnetism to shoot forwards. Almost all the force should occur in the horizontal portion while the forward pointing portion doesn't give any more force than a normal gun.
Kind of scary, espcially if the high speed projectile doesn't want to turn the corner at the end, not to mention the long lever arm will make the rails flap. Automatic fire will have to be timed.
The only problem left? electric power for something like this must be pretty big. Kinetic energy = 1/2 mv^2 so even a small m will require a lot of car batteries. I don't see 007 running around with this weapon protecting ski bunnies while his batteries freeze.
Know your pads. One time pad: good for cryptography. Two timing pad: where to take your mistress.
Call me crazy, but I'd rather make a friend than kill an enemy.
Unfortunately, not every enemy feels the same way.
So lets kill them before they kill us!..
You realize how many conflicts could have been avoided if someone had stopped and realized that the other side is human too? Very few people actually want to kill, and even less people want to be killed. People kill out of fear, and killing people because you dont want them to kill you is the worst abuse of logic around.
Im willing to bet that every enemy really does feel like they would rather make the friend. Don't get me wrong, I dont mind people running out and killing eachother, I just dont buy their justifications.
Now that weve gone completely off topic (as the original article wasnt even about guns), heres a bash.org quote!
what's your problem? Earth's orbital velocity is ~29.8km/s (thus Earth travels though space at 29.8km/s relative to the sun). those plates are travelling at 34km/s. is 34km/s not faster than 29.8km/s?
That said, that's significantly slower than Earth's `orbital' velocity around the center of the galaxy: 300km/s (yes, 0.1% c) assuming the sun is 100000 ly from the center of the galaxy and it takes 100 millioin years to go complete an orbit.
Bill - aka taniwha
--
Leave others their otherness. -- Aratak
Powering spacecraft or launching cargo or many other things...
How am I supposed to fit a pithy, relevant quote into 120 characters?
Rail guns are unlkely to be useful for driving implosions. It would be very hard to focus a symmetric implosion with a railgun. However, you could use the same pulsed power to drive an implosion like a plasma gun. Get a thin gold tube, fill it with DT, and whack in a pulse. The pulse goes up the outside of the tube. The gold outside goes directly to plasma, stops conducting, and so the current can move inward. If you can get the shockwave reaction from the expanding plasma to approximately match the speed of the current penetration, then a nice, cylindrically symmetrical implosion should be yours, and the small burst of annoying penetrative radiation and the hair loss that goes with it.
There is another effect - the Z-pinch - that is a bit railgun-ish. This gets a lot of mention in the Sandia webpage. People used to have great hopes for that - it was quite the thing in the seventies, when people could still use phrases like 'everlasting power from seawater' without laughing - but it is hard to get a symmetrical pinch before instabilities run riot.
Don't take my word for it. Maybe, I'm too old, and things have moved forward since I last was in this field. Sandia is a seriously cool place, even if the people who write their webpages are a bit too keen now and then.