A magnetic field will move charged particles, but, unfortunately, will also draw them towards the ship at the poles. Lasers are also a no-go as, even if the photons could somehow get through the warp bubble, your ship is moving faster than they are and they'd just collect at the edge of the bubble. The same problem applies to anything else originating from the ship, really. Unless we can figure out some sort of anti-gravity projector to push the particles out of the way ahead of the bubble, I don't think there's a viable solution.
Centrifugal force? If the warp bubble is spinning on the ship's axis, it would capture the particles, but push them out to the side.