The reaction would also be carried out in a differently shaped apparatus not a torus, but a cylinder with a magnetic field running along its axis.

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The metal returns up the outer cylinder, and electric currents create a magnetic field.

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As the particles enter the trap, the magnetic field forces them to travel in spiral orbits so that they cannot crash into the walls of the cylinder, and a strong electric field plugs up the far end, corking up that route of escape.

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