# Can a 400V 2200µF capacitor propel 0.5g through a rail gun?

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1. Aug 30, 2016

### Alexander Stroborg

I am planning to conduct an academic experiment involving an electromagnetic projectile.

I originally planned to build a rail gun powered by a 400V 2200µF capacitor, I've read a lot of discussions that say rail guns require a tremendous amount of current. Is this capacitor sufficient to propel a 5 mm ball bearing weighing in at 0.5g? I am not expecting to break the sound barrier, just enough to notice an acceleration; of course the projectile will have an initial velocity not to weld the projectile to the rails.

I've had doubts because of this and am thinking about a Gauss or coil gun as it typically requires less current. I have a bench power supply capable of 30V 6A or 60V 3A. Assuming the initiation and termination of the current in the coil gun is timed perfectly, will the rail gun or coil gun accelerate the projectile to a greater velocity?

2. Aug 30, 2016

### sophiecentaur

Hello and welcome to PF.
Before you ask for an answer to this one, have you calculated
1. The amount of Kinetic energy your ball bearing needs.
2. How much Electrical Energy your Capacitor will hold once it's fully charged?
Those formulae are easy to find with a quick Google search and they will give you an answer. You are proposing an "academic" experiment so a good academic initial approach to the problem would be worth while.
1. and 2. will give you two equations for Energy. You can combine these equations and find a value for the maximum v you can expect, under ideal conditions.
What information have you gathered so far about the details of rail gun construction? The more theoretical preparation, the better chance you have that the gun you actually construct will work and not just kill your power supply.

3. Aug 30, 2016

### Staff: Mentor

Welcome to the PF, Alexander.

We have a rule here about not allowing dangerous discussions, and when a person with little electronics experience asks for advice on how to build a rail gun or coil gun, that is a red flag for us. Please start with some safer projects that are not focused on releasing large amounts of energy in such a short time, and that don't involve voltages over about 60V ("SELV"). Thread is closed.