Well you can make an exit "pipe" that
lets some of the packets fly straight, and not get
dragged into the ring.
(turning off the magnets in a pulse, or using a second magnet)

If you put the hand onto the exit-pipe, it should
keep the air long enough outside the vacuum tube
to have an effect.

its the whole idea to first accelerate particles, and then
let them fly outside of the accelerator ring.

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