Partical Effect water Fountain

I have created a circle in a modeling program and have set it as the mesh. I set the particles to emit from the edges of it so that they go up leaving a circle hole in the middle. The problem I am not sure how to do is making the particles go wider in a circle as it goes up so that I can add force to make the particles come back down in a fountain shape.


simply you can change the radius in shape of particles settings to be wider.