How Does A Railgun Work

The physics of a railgun

Practice you want to shoot a projectile actually, really fast but don't accept whatever explosive propellant? Do you have little more than a couple of metal bars and a very big battery in your garage with which to practise it? Then maybe you should look into railgun technology.

Based on rather simple principles of electromagnetism, a railgun is a system which uses electricity to accelerate a projectile to mind-boggling speeds of several times the speed of sound.

Although simple on the surface, its immense technological and engineering challenges have meant railguns are nonetheless in relatively early stages of evolution. Due to strong promise in military awarding, organisations like the United states of america's and China's militaries are some of the few actively pursuing it.

Nevertheless, potential peaceful applications besides exist. In particular, railguns could be used to send small payloads into Earth's orbit without needing to include heavy fuel in said payload.

How it works

When an electric current is placed in an external magnetic field, it experiences a force perpendicular to both the magnetic field and current directions – this is known as the Lorentz force. That'south basically all there is to a railgun'due south action in terms of physics.

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The projectile is held by a conducting armature which is in betwixt two parallel conducting metal confined (the rail). A very, very strong current is passed down the first rail, through the armature, and into the second rail. The currents in the rail produce a strong magnetic field which interacts with the current in the armature, launching it out at potentially stupendous speeds.

And so why can't you build something like this correct out of your garage?

Not equally easy as it seems

You could, only the projectile won't go very far or very fast. The key to unlocking the potential of this technology is the sheer book of energy required. Currents of millions of amperes, which require tens of megajoules of energy, are needed.

For context, that'southward nearly the daily energy consumption of one household, but delivered in the course of a few milliseconds over a couple of metal rods. So while storing that much energy isn't besides crazy, releasing it all at once is the real claiming.

And one time that energy is released, in that location are a bunch of other problems that make operating a railgun most impossible.

Heat, force, and dispatch

The million-amp currents in the runway and armature misemploy into extraordinary amounts of heat due to electrical resistance. This calls for materials with high conductivity (low resistance), high melting points, as well equally agile cooling systems. Besides, the speed of the projectile itself crashing through the air gets things pretty hot, too.

Another issue arises when we call back the fact that every action has an equal and reverse reaction. A force equal to that imparted on the armature and projectile is also felt past the rails themselves, threatening to bend and break them. So the material they're made of has to be extremely strong and stiff in addition to the previous considerations.

Finally, the projectile itself experiences accelerations of incredible magnitude, on the club of 10,000 to 100,000 k (i g is the dispatch during freefall). Unless it is made out of very tough stuff, whatever is being launched would get obliterated before exiting the gun.

This is one of the most serious issues when it comes to launching satellites: just sturdy, robust payloads (and definitely not humans) could be launched.

In conclusion…

The concept behind railgun propulsion has been around since the mid-1800s, but even with the resources of the globe'south largest militaries, the railgun is withal more of an experiment than a useful weapon or satellite launcher. It is a dandy example of when applied science challenges far outweigh the scientific ones.