add repulsion force to particle physics

[Vance]

The "contact" in Particle Physics collisions is illusory. All it's doing is applying a repulsive force when 2 particles are within range. The attraction does the opposite. The only reason they're separated is so you can apply both types of forces with different radii within the same operator, but they do the same things, just inverted. Just drop the collision force value way down if you want to lessen the "contact" effect.

You can also use the Flock operator for attraction/repulsion forces that are set to a certain velocity, rather than a function of the distance between particles.

I'll try changing the collision strength to see if I can get it to do what I want.  

 I think I may be looking for something that is more like a raycast avoidance but for other particles.