Looking for help understanding Z position in relation to 2D particle systems

Hello, I have been tinkering with particle systems for the past couple weeks and I mostly reason about them in two dimensions. I have a hard time reasoning about them because of the Z axis. I have a few questions about this:

* My particle system's Scale has a Z value. Does this mean particles can be emitted and move along the Z axis? I'd prefer they maintain a Z position of zero, consistent with other game objects, to avoid unexpected interactions, should as failing to collide with a layer, accidentally being occluded by a layer, or failing to interact with a force field.
* I've introduce a particle system force field with a hemisphere shape which wants to rotate on the Z axis. Rotating it on the X or Y axis seems to reflect a rotation that's taking place in 3D. It's fine if the Z value is sitting there doing nothing, but now I'm unsure about how to reason about the direction this force field is pointing.

 

Yes the particle can move in the Z axis since it is not limited to just 2d after all

 

Is there a good way to prevent it from moving along the Z axis?