There are some materials that block magnetic fields from going to the other side. I was wondering if it was possible to make a coil gun and block the magnetic fields that exist on the back half of the coil. As the coil pulls the projectile towards it initially, and after the projectile passes, it will try to pull it back, causing losses.
In my experience with physics, I see many parallels between liquids, electricity, gravity, and magnetism. Examples being, someone made a computer based on liquid diodes. Also heat increases conductivity with clamping pressure, so does electricity.
This makes me believe that the magnetic field is similar to electivity. Flowing in a direction. Therefore if half of the field was blocked, it would interrupt the field and weaken it, making magnetic field blocking useless.
However, I suppose that if you would insulate the projectile tube only, the outside magnetic field would be largely unaffected and would still complete its circuit. The projectile would just stop being effected by magnetic fields after entering the insulted tube.
If so you could likely get rid of all the complex hardware with multiple coils and timing mechanisms, and just have one giant coil, that could be cooled with liquid gas, and one tube that is half insulated.