In a railgun the lorentz force causes an object to be propelled

[Bugmenot]

In a railgun the lorentz force causes an object to be propelled in a direction because of an electromagnetic force caused by running a current through the "rails". How come you can use aluminium or another such non-magnetic metal as both rails and armature? Surely only a magentic metal would work?

 

[Andrew Mason]

In a railgun the lorentz force causes an object to be propelled in a direction because of an electromagnetic force caused by running a current through the "rails". How come you can use aluminium or another such non-magnetic metal as both rails and armature? Surely only a magentic metal would work?

You are interested in the ability of the metal to conduct electricity. The magnetic field is due to the current in the rail and projectile/armature. The design does not allow for the use of high permeability core material since there is no core.

AM

 

[Astronuc]

In a railgun the lorentz force causes an object to be propelled in a direction because of an electromagnetic force caused by running a current through the "rails". How come you can use aluminium or another such non-magnetic metal as both rails and armature? Surely only a magentic metal would work?

First of all, Al is cheap/inexpensive.

The effect is I x B, and B is induced by the currents in the rails, so a magnetic material is not necessary.

Al is relatively low density (sg ~2.7) as compared to steel (sg ~ 8.0), so for the same size, the Al would have much less mass, and consequently for a given force, it would accelerate faster.

I have seen railguns with copper rails which were used to fire steel projectiles - up to several km/s - for a relatively short gun.

 

[Bugmenot]

So, in english, what your saying is it doesn't have to be ferromagnetic to get a magnetic field. Thanks

 

[leright]

The magnetic field is produced by the current in the aluminum wire and NOT by a magnetic moment in a permanent magnet. Therefore, conductivity of the conductor is what is important, an Al is a very good conductor, and it is cheap.

 

[Corkie2003]

Why can't they use maglev to fire projectiles?

No contact, no friction!

 

[Elementric]

Probably because you would have to have a very long vacuum tube from your device to your target for it to make any significant difference.