How to keep dense particles at the center of emitter in blender 2.8? I'm trying to make my emitter space look dense with the particles while emitting the particles. I'd done a setting which gave me the desired result but it was a hidden trial, now i'm trying to search it out for 4 days but not getting the setting exactly. I have added two pictures showing differences at center 
Please try to help me if anyone could.   Thanks. 

High density particles at center.


Low density particles at center or no my emiter
So as stated in a comment, you can have two particle systems.

One (in green here) is the "outer" system. The other one (in red) the "inner" system.

By giving different lifetimes and initial velocities to your systems, you can probably approach your desired result.



Green is long lived with high velocity



Red/inner is short lived and with low velocity