Niagara collision questions

I have issues with making collision work -
I have a mesh shaped emitter with particles hovering around the shape of the mesh. (already working with BP)
I would like to push/collide the particles with another mesh (not collision between particles) or with an attractor/effector that pushes or attracts particles within a certain range. Like a small vector field I can move around or similar.
However I cannot seem to find the right approach or tutorial or documentation (I know it is still in early access). So far I can only make the (cpu) particles collide with each other. Not with other meshes/actors.

Any guidance, references to where to start or tutorials are warmly welcome.

Cheers,
Søren

Regarding the first question (colliding with meshes), the Content Examples project (Epic Launcher > Unreal Engine > Learn Tab > Content Examples) contains a *Niagara *demo level. This level has several demo displays. Demo display 2.6 Simple Collision demonstrates particle collision with static mesh actors using a CPU sim. I changed it to GPU sim and the collision still worked, though the result was visually quite different. To show the collision working I modified *SimpleCollision_System *to disable one of the emitters, and I also change some parameters to make the particle emission less random.

You will notice the GPU sim version is not firing the collision event that kicks off the secondary (small red) particle effect, but it is colliding with the static mesh actor (the sphere).

**CPU Sim of Modified SimpleCollision_System

GPU Sim of Modified SimpleCollision_System

SimpleCollisionEmitter’s Particle Update Section

Emitter.PNG**