Particle tracing, how to release particles?

Hello,

I am using the particle tracing module in comsol 4.2 to track charged particles in an electric field in 3D geometry. I basically need to release particles from the top plane of a cube and tract their motion towards the bottom plane in an electric field.

I know how to release multiple particles simultaneously using the range function. If I use X=range(0.3,0.02,0.7) and Y=range(0.3,0.02,0.7) and Z=constant, then I get a line of particles released. (see image what_i_get)

How do I get a 2D grid of particles released simultaneously? (see image what_i_want)

Can someone please help me with this?

Thanks,
Aditya