How Do I Determine Coil Specifications for a Coilgun?

[ZaiGuy]

Hello all.

I am in the process of designing a coil gun, currently using a three stage design. The first stage will have four 1000uF @ 400V capacitors in parallel, a thyristor controlled by a mechanical switch and the coil with a flyback diode in parallel and reversed from the coil.

The second and third stages will have the same configuration, but be triggered optically (by triggers in the barrel) and only have three caps each.

My question is this: how do I determine the wire gauge, length, thickness and any / all other specks for the coils for optimal performance?

The attached PDF is the current schematic.

[S57UUU]

With this circuit (all caps parallel) the first thyristor will discharge all of them thru the first coil. Use diodes in the charging circuits.