Plasma is essentially superheated Hydrogen, hence a superheated gas. You can't, however, have plasma Helium, because when it becomes plasma it has split apart into Hydrogen. Some people call it a gas, others a new state. I believe that theoretically you can get it hot enough to disintegrate the protons, neutrons, and electrons, but that last part I'm not at all certain about.
~J
Full Version: Some Rail Gun Issues
| QUOTE (Frag-o Delux) |
| The little I now about it, showed that they superheated a gas and to move it from one spot to another they pushed it through a magnetic tube so the plasma wouldn't touch the container and burn through. |
Actually, that is a configuration currently tested for nuclear-fusion reactors. The magnetic field is used to contain the reactive plasma in a circular "orbit" within a torus-shaped reactor to keep it from frying the shielding materials
As for the nature of plasma:
Plasma doe NOT destroy the sturcture of the atom's core. Otherwise it would neither make any sense to make a list of elements the sun consists of nor would nuclear fusion work (as you need to heat the hyddrogen to turn it into plasma before you have an energy-level sufficient to allow the hydrogen atoms to merge into helium atoms - if plasma would destroy the subatomic structures of the material, this wouldn't work). Plasma OTOH does inded consist of ions i.e. the outer electrons are separated from the atomic cores and roam freely in the plasma cloud, giving it certain eletrical properties similar to metals.
(sorry, if I made any mistakes about the correct scientific terms, but unlike my math and computer-science books, my literature on this stuff is purely in german...)
I stand corrected.
~J, who really needs to stop sleeping through Physics
~J, who really needs to stop sleeping through Physics
So if you tried to make Helium into plasma would it stay Helium or would it break down to Hydrogen? Camo said the atomic structure would stay the same so I am assuming Helium would still stay Helium. I think I remember Helium listed to be present on the Sun. Sorry I am not very familar with Plasma. I have not been in a chemistry or physics class in 9 years.
You forgot Bose-Einstein condensation, which might be considered another state of matter 
. Not to mention the 'fully collapsed' matter which may occur at absolute zero...
The plasma state of matter is when the electron gets energetic enough to 'jump' fully out of their orbits, producing a 'gas like' substance that consists of atomic nuclei and free electrons. The atomic nuclei themselves hold together.
This means that plasma will conduct electricity in much the same way metals will (has a cloud of free electrons). Notice that you can get plasma that is not 'very hot' by simply using very 'empty' environments. Iirc this is how fluorescent lights work. By having a very small amount of gas in an evacuated tube, then electrifying that gas until it becomes plasma (and gives off light).
. Not to mention the 'fully collapsed' matter which may occur at absolute zero...The plasma state of matter is when the electron gets energetic enough to 'jump' fully out of their orbits, producing a 'gas like' substance that consists of atomic nuclei and free electrons. The atomic nuclei themselves hold together.
This means that plasma will conduct electricity in much the same way metals will (has a cloud of free electrons). Notice that you can get plasma that is not 'very hot' by simply using very 'empty' environments. Iirc this is how fluorescent lights work. By having a very small amount of gas in an evacuated tube, then electrifying that gas until it becomes plasma (and gives off light).
...and some folks have been talking about using "cold plasmas" as a form of energy shield for satelites, or something of the sort...
[snip]
Camouflage beat me to the point
In addition to the elements in stars, heavy alkaline metals like cesium and potassium are popular in plasma research because they form plasmas at very low temperatures, like 900C.
Camouflage beat me to the point
In addition to the elements in stars, heavy alkaline metals like cesium and potassium are popular in plasma research because they form plasmas at very low temperatures, like 900C.
| QUOTE (Frag-o Delux) | ||
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| QUOTE |
| Currently, there are a number of major technical problems that must be overcome if railguns are ever to be used on the battlefield. Available power sources are too large and weigh too much for field applications (particularly for vehicle-mounted systems). When the gun is fired, the electric arc set up between the rails causes severe rail erosion, particularly near the breech end where the projectile is moving slowly. This causes such rapid rail deterioration that many railguns have to be refurbished after only one or two shots. |
The SR railguns were changed to Naval damage in editing. They were originally just very high Power vehicle scale.
Hey! I was right about Plasma! Whoulda thunk?
What I thought would be neat for a plasma cannon would be different types of shot. Normal opponent, use the iron pellet (and the gun makes it into plasma). Fighting a supernatural - use a silver (vampire/werewolf) or gold (demon) pellet. Etc.
Oh, and helium is the by-product of the fusion of hydrogen (in the sun). Note that helium can fuse to become a heavier element, and still give off energy. I think that any element lighter than iron can be created (by fusion) and still give off energy. Anything heavier than iron needs an energy input to fuse - that's what uranium is - it's created in the blast-furnaces that are supernovae
What I thought would be neat for a plasma cannon would be different types of shot. Normal opponent, use the iron pellet (and the gun makes it into plasma). Fighting a supernatural - use a silver (vampire/werewolf) or gold (demon) pellet. Etc.
Oh, and helium is the by-product of the fusion of hydrogen (in the sun). Note that helium can fuse to become a heavier element, and still give off energy. I think that any element lighter than iron can be created (by fusion) and still give off energy. Anything heavier than iron needs an energy input to fuse - that's what uranium is - it's created in the blast-furnaces that are supernovae
Seems like this thread dropped away a few months back. Luckily I did a search on the posts and found the thread before I started one of my own tonight...anyhoo, my general questions were going to be whether it was feasible/possible to have a man portable 'railgun' (coilgun, or however its setup, I admit I don't know enough about the real life tech behind it) and what it would look like.
After looking over the various responses, I still have a few unanswered questions.
1. It seems the gist of the various responses is that railguns may not be practical in a man portable way. Is this to say that an effective railgun setup sorta like a sniper rifle or assault cannon, is technologically more difficult to field/put together than a man portable laser gun (Ares MP laser 3 for example) in the SR universe? I've seen a few posts talking about the real issues being making the alternating process between coils or whatever fast enough. In the current SR timeline, which allows for Smartguns, headcyberdecks, suped-up cyberware that even when you pretty much replace your whole body, doesn't need a portable mininuke to power it, wouldn't it be likely?
2. Probably more of a real life science question. But why would a railgun/coil gun have recoil? From my less than informed background, I always thought recoil was a function of the bullets exploding and leaving gasses, and thought a railgun was more like a superhighpowered bolt thrower like a crossbow.
3. Would dikote coating of rails/coils or use of molecular bonded materials of the type used in the dikote-substitute 'courage fineblade knife' stuff be a way to prevent wear and tear on the railgun's ejector system?
4. If you were using the powerpacks that came with the Ares mp laser 3, sufficient to give the laser 20 shots, how many shots would you get if using it to power your railgun system? More? Less? Kinda related to question #1 I guess.
After looking over the various responses, I still have a few unanswered questions.
1. It seems the gist of the various responses is that railguns may not be practical in a man portable way. Is this to say that an effective railgun setup sorta like a sniper rifle or assault cannon, is technologically more difficult to field/put together than a man portable laser gun (Ares MP laser 3 for example) in the SR universe? I've seen a few posts talking about the real issues being making the alternating process between coils or whatever fast enough. In the current SR timeline, which allows for Smartguns, headcyberdecks, suped-up cyberware that even when you pretty much replace your whole body, doesn't need a portable mininuke to power it, wouldn't it be likely?
2. Probably more of a real life science question. But why would a railgun/coil gun have recoil? From my less than informed background, I always thought recoil was a function of the bullets exploding and leaving gasses, and thought a railgun was more like a superhighpowered bolt thrower like a crossbow.
3. Would dikote coating of rails/coils or use of molecular bonded materials of the type used in the dikote-substitute 'courage fineblade knife' stuff be a way to prevent wear and tear on the railgun's ejector system?
4. If you were using the powerpacks that came with the Ares mp laser 3, sufficient to give the laser 20 shots, how many shots would you get if using it to power your railgun system? More? Less? Kinda related to question #1 I guess.
| QUOTE (Voran) |
| But why would a railgun/coil gun have recoil? From my less than informed background, I always thought recoil was a function of the bullets exploding and leaving gasses, and thought a railgun was more like a superhighpowered bolt thrower like a crossbow. |
Didn't this thread answer this question? [Edit]Apparently not. Must have been some other rail-gun related thread...[/Edit]
No, recoil is not a function of the explosion. It is a function of several issues, usually most important of which is the bullet leaving the barrel. This is what will cause the recoil on the rail gun as well. Newton's third law, conservation of momentum, and all that.
The propelling gases escaping the barrel of a conventional firearm do factor into the recoil, so a railgun might have less recoil than a conventional firearm at the same projectile weight and velocity. On the other hand, gas venting systems (like muzzle brakes) use the gases to reduce the over-all recoil, while there's not much that can be done to reduce the recoil on a railgun.
| QUOTE (Voran) |
| 1. It seems the gist of the various responses is that railguns may not be practical in a man portable way. Is this to say that an effective railgun setup sorta like a sniper rifle or assault cannon, is technologically more difficult to field/put together than a man portable laser gun (Ares MP laser 3 for example) in the SR universe? I've seen a few posts talking about the real issues being making the alternating process between coils or whatever fast enough. In the current SR timeline, which allows for Smartguns, headcyberdecks, suped-up cyberware that even when you pretty much replace your whole body, doesn't need a portable mininuke to power it, wouldn't it be likely? |
You could probably tote around a small railgun. It just wouldn't be the powerhouse that everyone thinks about when they hear about a railgun, probably closer to a small-caliber sporting rifle.
| QUOTE (Voran) |
| 2. Probably more of a real life science question. But why would a railgun/coil gun have recoil? From my less than informed background, I always thought recoil was a function of the bullets exploding and leaving gasses, and thought a railgun was more like a superhighpowered bolt thrower like a crossbow. |
As mentioned previously, recoil is a result of Newton's third law. You're throwing a slug at high velocities, and so the gun is going to be pushed back with the same momentum. It may be pushed back over slightly more time, however.
| QUOTE (Voran) |
| 3. Would dikote coating of rails/coils or use of molecular bonded materials of the type used in the dikote-substitute 'courage fineblade knife' stuff be a way to prevent wear and tear on the railgun's ejector system? |
To reduce, yes. To eliminate, probably not. I'm not sure if it'd be enough to cause problems with conductivity, but if not, it'd be a good way to get a few more shots out of a railgun.
| QUOTE (Voran) |
| 4. If you were using the powerpacks that came with the Ares mp laser 3, sufficient to give the laser 20 shots, how many shots would you get if using it to power your railgun system? More? Less? Kinda related to question #1 I guess. |
Absolutely no idea. There's not enough information about what constitutes a "shot" or the power output provided. That's something that would have to be determined on a by-GM basis.
~J
| QUOTE (Voran) |
| 1. It seems the gist of the various responses is that railguns may not be practical in a man portable way. Is this to say that an effective railgun setup sorta like a sniper rifle or assault cannon, is technologically more difficult to field/put together than a man portable laser gun (Ares MP laser 3 for example) in the SR universe? |
No. Railguns should be easier. The basic mechanism for propelling the projectiles is pretty simple - witness the hobbyists who make railguns in real life. The stumbling block is the power supply, but once you have that for lasers, the rest is fairly easy.
| QUOTE |
| 2. Probably more of a real life science question. But why would a railgun/coil gun have recoil? |
Because you threw a projectile in the opposite direction. Like Newton said, "For every action, there is a reaction." You don't escape that just because you're moving the bullet magnetically.
Try this experiment at home:
1) Get two kitchen magnets.
2) Set one the table.
3) Hold the other with the tips of your fingers.
4) Arrange them so they'll be attracted to each other.
5) Move the magnets together, so the one on the table jumps to the one in your hands.
Question: When they came together, did you feel the magnet in your hand try to tug away, trying to jump to the one on the table?
Now consider a coilgun: the magnetic coils in the barrel pull the projectile forward. Likewise, the projectile will be pulling the magnets in the barrel backward. Since the magnets are attached to the barrel (which is attached to the frame, which is cradled in your hands), they push the coilgun back into your arms.
Food for thought: NASA has considered using railguns/coilguns for propelling asteroids, using waste material from asteroid mining operations. Would that sort of "railgun rocket" work if there was no recoil?
| QUOTE |
| 3. Would dikote coating of rails/coils or use of molecular bonded materials of the type used in the dikote-substitute 'courage fineblade knife' stuff be a way to prevent wear and tear on the railgun's ejector system? |
Well, you mean the rails themselves in railguns. (Calling two electrified rails a "system" is being unnecessarily fancy.) Coilguns don't have much of a wear problem.
But, yes it would reduce wear, perhaps to the level normal bullets inflict on conventional gun barrels. Dikote and related materials may be the needed breakthrough to make railguns battlefield viable. Diamond can be made fairly electrically conductive and it's already very thermally conductive, on top of being hard.
| QUOTE |
| 4. If you were using the powerpacks that came with the Ares mp laser 3, sufficient to give the laser 20 shots, how many shots would you get if using it to power your railgun system? More? Less? Kinda related to question #1 I guess. |
For the same damage rating, railguns and coilguns should be more efficient with energy. They involve fewer conversions between forms of energy. Lasers loose energy everywhere - in the lasing process, at the target's surface, in the cloud of plasma formed at the impact point, etc. Railguns and coilguns loose energy due to electrical resistance, and then due to aerodynamic drag like any bullet. Their projectile's deliver energy neatly like any bullet.
Therefore, for the same amount of damage, railguns and coilguns should get more shots. I'd probably leave the actual number of shots alone and just be happy I had a man-portable railgun, but you could argue for just about any number of shots per battery pack you wanted.
Cray beat me to this. Basically, though, a gauss gun is fairly simple to build. If you go to your local Radio Shack, you can buy enough parts to build a decently powerful coilgun, using solenoids. (The solenoids from a pinball machine can fling a 16-oz pinball all over that machine. Daisy-chain them together, and you can get a 3 oz ball bearing up to some impressive speeds.)
The technology and expertise required to build a very powerful gauss gun is not very complex. Making it man-portable, and improving the power source, are the only real complications.
The technology and expertise required to build a very powerful gauss gun is not very complex. Making it man-portable, and improving the power source, are the only real complications.
That's one of the wonderful things about coilguns/railguns; instead of having to improve the overall design, you can add velocity by just adding length.
~J
~J
Railguns? Hmm, Red Faction... Metal Gear Solid 2...
| QUOTE (John Campbell) | ||
You mean like the Xicohtencatl Light Railgun? At 135kg, it's light enough to fit on pretty much anything that can take a hardpoint. I designed a miniblimp drone with one on... nothing says fun like 6LN from the heavens. |
Man, you are the sickest person in the history of Dumpshock!
6LN from the air without potential collateral? Name ONE megacorp who wouldn't want that! The Draco Foundation would go nuts! And the UCAS!
By the by, does anyone have any number for the following: estimated duration of acceleration for a rifle bullet fired normally, estimated duration of acceleration for a railgun firing a slug of equal weight to that bullet from rails the same length as the barrel of the rifle, weight of a typical rifle bullet in kilograms? I'm in a discussion with someone as to whether or not the felt recoil from a railgun would be less than that from a rifle. I guessed .05 seconds for the rifle and .25 for the railgun, but that means that you can sling a railslug at five times the muzzle velocity of the bullet with the same impulse, which just seems wrong.
~J
~J
| QUOTE (Kagetenshi) |
| By the by, does anyone have any number for the following: estimated duration of acceleration for a rifle bullet fired normally, estimated duration of acceleration for a railgun firing a slug of equal weight to that bullet from rails the same length as the barrel of the rifle, weight of a typical rifle bullet in kilograms? I'm in a discussion with someone as to whether or not the felt recoil from a railgun would be less than that from a rifle. I guessed .05 seconds for the rifle and .25 for the railgun, but that means that you can sling a railslug at five times the muzzle velocity of the bullet with the same impulse, which just seems wrong. ~J |
Er...the acceleration's kinda variable in both cases, depending on muzzle velocity, powder type, barrel length, etc.
For a 1-meter barrel, a 1000m/s muzzle velocity, and continuous, even acceleration, a railgun projectile would need .002 seconds to clear the barrel. That corresponds to 51000G's.
I suspect a rifle bullet will see approximately the same overall launch time, with acceleration higher near the breach (breech?) and lower at the muzzle.
What's a typical rifle bullet?
A 7.62x51mm NATO/.308 Winchester typically spits out bullets between 150 and 200 grains/9.72 and 13 grams. That's a common GPMG/sniper rifle/battle rifle/sporting rifle caliber.
For a low-recoil comparison, a 5.56x45mm NATO/.223 Winchester typically fires bullets between 50 and 65 grains/3.24 and 4.21 grams.
Lots more rifle bullet weights here. 1 grain = 0.0647989 grams.
No idea how long it takes for those bullets to accelerate (ie. leave the barrel, since it will accelerate up to that point anyway).
A 7.62x51mm NATO/.308 Winchester typically spits out bullets between 150 and 200 grains/9.72 and 13 grams. That's a common GPMG/sniper rifle/battle rifle/sporting rifle caliber.
For a low-recoil comparison, a 5.56x45mm NATO/.223 Winchester typically fires bullets between 50 and 65 grains/3.24 and 4.21 grams.
Lots more rifle bullet weights here. 1 grain = 0.0647989 grams.
No idea how long it takes for those bullets to accelerate (ie. leave the barrel, since it will accelerate up to that point anyway).
| QUOTE (Cray74) |
| I suspect a rifle bullet will see approximately the same overall launch time, with acceleration higher near the breach (breech?) and lower at the muzzle. |
Probably a lot higher near the breech, since lengthening the barrel on an already full-length rifle won't result in much better muzzle velocity, while shortening it will cause a significant drop. Plus it just makes sense, because of the whole gas expansion thing and more energy required and all, but you probably knew that already.
By saying "a typical bullet" I was more or less saying "I don't know what I'm talking about, pick one for me please"
~J
~J
Then the 7.62x51/.308Win will probably suit you just fine. The muzzle velocity is up to ~3000fps/915mps for the ~150gr bullets, up to ~2700fps/825mps for the ~200gr bullets. Typical 180gr/11.7 gram bullet has a muzzle velocity of 2700fps -- at least that's the most common entry on my G&As and hunting mags.
| QUOTE (Kagetenshi) |
| By saying "a typical bullet" I was more or less saying "I don't know what I'm talking about, pick one for me please" ~J |
A railgun fires its projectile in a period measured in thousandths of a second. I suspect a conventional rifle does the same. At that timescale, I further suspect that variations are going to be meaningless to the human musculature absorbing the recoil. It's just one short, sharp shock either way you handle it.
Even then, if it's a difference between .001 and .002, the latter is still half the Impulse...
~J
~J
| QUOTE (Kagetenshi @ Mar 3 2004, 08:35 PM) |
| Even then, if it's a difference between .001 and .002, the latter is still half the Impulse... ~J |
Again, that won't matter to flesh and bone. The total momentum delivered is the same.
You'll probably see a bigger effect on recoil out of something that genuinely stretches out the recoil, like shockpads or body fat, than you will from differing accelerations that result in the same muzzle velocity.
| QUOTE |
| just as a comment these must be extreamly scaled down railguns because if you accelerate a metal projectile any where near the speed of light (wich is what most people asume you want) |
* Speed ... of ... light?! Wasn't that one of the lame babbletech lines they spit out in the movie Eraser?
| QUOTE |
| but also the air friction (even if the slug deteriorates) would cause sevear burns on any thing it passed near |
* At speeds anywhere CLOSE to the speed of light (even tiny fractions) the projectile would EXPLODE before it left the railgun! The armature would have to be built from some unobtanium material to withstand the MASSIVE amount of frictional heat that would generate. And good gravy would that thing be noticeable -- just the heat flare and plasma trail it would leave behind it ... yowza.
| QUOTE |
| AFAIK, both railguns and gauss weapons (coil guns?) are energy pigs. The difficulty is delivering the energy fast enough; many common electrical storage systems and fuels have more than enough energy. |
* This isn't a problem for weaponized railguns. Modern homopolar generators and supercapacitors can pump out enough juice for any battlefield railgun. The problem is that they tend to be bulky and thus difficult to fit into a vehicle smaller then a semi-trailer.
| QUOTE |
| Yes, very interesting. But really, Railguns will not come into weapon range in our life, so it is just a dream |
* Don't count on it. Directed energy weapons are getting more funding dollars and publicity, but expect to see railguns in the air-defense and anti-armor role in some capacity by 2020.
| QUOTE |
| If you worried about recoil on an orbital platform, simple lengthen the barrel and load up on some mass packets to counteract the pushing force of the weapon. I don't the exact math but you have a 100kg crowbar shooting down at the planet at hyper speed, then you counter launch a 200kg mass packet in the opposite direction at the equivalent speed. Either that or you fire a counter thruster. |
* Why bother? Just kick the shot out of the garage with a cold-gas bump and fire a small rocket to adjust as necessary, then let gravity do the rest.
| QUOTE |
| Thoes numbers are from a diffeent thread, I don't know how they came up with them, Austere. Tzeentch said he wrote something up for railguns and I happened to know where to look for it. You can debate the numbers I was just trying to see if I could help Tzeentch. It seems like meny other topics, this one has come up a lot before. |
* I own 3G3, but did not design the railguns using that system. I built them using GURPS Vehicles as a TL9 railgun + TL10 or 11 power pack (because noone wanted to get into PF/shot). Then I used my GURPS --> Shadowrun conversion notes to get a damage code. This damage code was INCREASED by Rob during editing, but it looked fine to me (given how crazy ass the high-end of the SR damage system is anyways what does it matter?). I posted the GURPS mechanics for the railguns back when Rigger 3 came out.
| QUOTE |
| The technology and expertise required to build a very powerful gauss gun is not very complex. Making it man-portable, and improving the power source, are the only real complications. |
* That's probably understating the issues:
| QUOTE |
| For example, in order to accelerate a 4-kg projectile to 2.5 km/s in an 8-meter-long system with an inductance per unit length of 0.4 mH/m, a current of over 2.7 MA would be required. |
* That's a pretty hefty requirement!
| QUOTE |
| You mean like the Xicohtencatl Light Railgun? At 135kg, it's light enough to fit on pretty much anything that can take a hardpoint. I designed a miniblimp drone with one on... nothing says fun like 6LN from the heavens. |
* It came out that light with that much power because the damage was beefed up in editing and Shadowrun uses some pretty damn cinematic energy densities (you could probably short out the MP Lasers energy cell and create a pretty big explosion) so the energy storage component came out really small. To keep size and mass down you're probably more likely to see explosive power generation systems, but Shadowrun didn't have that when the railguns were introduced way back in the Aztlan sourcebook.
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