No howto for the Railgun? This will be fun! =)

How to make a Railgun in 7 easy steps:

1. Get a nuclear power station. This isn't completely necessary, in fact it's very much over kill. But access to a nuclear power station will ensure that you have a great power source
2. Get two extremely powerful, extremely fine UV lasers and align them so that they're firing their beams parallel to each other and are separated by about 1mm. You'll probably want ot mount them in a box of some sort too. Make sure that the beams are hitting a VERY good insulater because they'll be carrying a huge current. What? Beams of light carrying current? Well, that's not really what's happening, but it'll do for our purposes. If you do mount the lasers in a box then drill a hole in between where the lasers meet the insulater at the end of the box. This is where our slugs will be coming out of the box at about 143 meters per second.
3. Get two really strong magnets that are about 1m in length (about one tesla each would be good) and glue them to the top of your box above and below the lasers so that the north poles and south poles are facing (see picture below). You'll probably have to reinforce the box somehow because the slug will be exerting a HUGE (big, big, big) force on them. About 500N which is like supporting a 50kg person standing on them.
4. Get some REALLY small ball bearings (diameter of about 1mm) and find some way to get them to fall EXACTLY in between those laser beams. After we have finished, the balls will hit the laser beams and accelerate at about 10,000 ms^-2 so it's pretty important that they fall into these beams at 90 degrees to the lasers, otherwise they'll hit something in the box and cause BIG damage
5. Get some superconducting material of some sort...
6. This superconducting material will carry the current from the power station to your laser beams. Of course we don't want the -ve and +ve electrodes to get too close (we're dealing with a potential difference of about 50,000 volts)...Now these electrodes need to supply the electricity to the laser beams so that the beams actually have a potential difference across them. But by doing this you cannot block the beams with the wires so make them thin.
7. GET OUT OF THE WAY OF THE GUN, flick the switch and aim it towards the sky. You can drop a ball bearing into the beams and know that you have a working railgun!

Diagrams:

```
|-------------------------------|

1m

_______________________________
|                             |
_       - ===== - - - - - - - - - - - - - - #
| 1mm         |          O                     ->
-       + =====- - - - - - - - - - - - - - -#
|_____________________________|

_______________________________
|          Magnet              |
| N     N      N     N     N   |
+     ------------------------------     O  ->
| S     S      S     S     S   |
|__________Magnet______________|

```

It's really important to get the poles of the magnets and the electrodes right otherwise you'll probably end up with another oriface in your body.

How does this work?

Unless people want me to, I won't go into the deal with the UV laser...
When the ball bearing drops into the lasers, it is closing a circuit and thus carrying a current. There are technicalities involved due to the UV laser stuff, but I won't go into that. Anyways, the ball is therefore carrying a charge and accelerates due to a Lorentz force created between the magnets and the ball. This is why the magnets need reinforcement. I worked it out to require a potential difference of about 50,000 volts across the lasers* and a 2 tesla magnetic field. This will supply a force of 500 newtons and the ball, weighing about .0005 grams will accelerate at about 10,000 ms^-2. This acceleration lasts for a fraction of a second, though, which means that the bearing comes out with a speed of about 500kph. This is pretty slow by railgun standards, but it'll be fine for our purposes. If you really want to kill someone then I'd suggest that you buy a real gun...

I don't suggest you try this at home. I imagine that it would be rather hard to try, but if you do have access to the parts required then DON'T try it still. You're dealing with some pretty deadly stuff here and I'd hate to lose a fellow noder to a homemade railgun experiment.

*Of course, you need to somehow find a way to prevent current leakage across the lasers.

/msg me if you want me to add/take something
Deadbolt says a railgun isn't a railgun unless it fires slugs made of depleted uranium :)