Particles flow along curve only one direction

Good Morning Everyone,
I hope someone here can help me with this problem I am facing.
I am working on a simulation in which particles are supposed to represent an electric flow. I already managed to make the particles flow along a path the way I want them to. But it seems like some bends are to narrow so the particles flow back the wrong way. Is there some way to prevent this from happening?
Thank you kindly for your support.