two magnets arnt being cooled, check alignment/rotation, and since the plasma is going straight out from the injectors and I don't see the sparks between them, so it doesn't look like they are being powered.
Indeed. You need to run LN2 to the two toroids just below the left most injector, place a powered Van de Graff below one of the toroids, rotate the injector tile entities in your injectors so they are all pointing in the same direction (clockwise or counterclockwise, your choice), and supply power to the solenoid in the center if you aren't already.
The thing does actually have VDGs, I'm just to far away for them to be rendered. Also added the missing pipes. And I fixed the two injectors (I never knew which side they were placed from made a difference - thanks for your hint Reika!)
Now it's working.