For this animation I combined a volumetric material and a particle system
To achieve the light effect I placed the particle system in a box with a that only uses a "Volume Scatter"-node in the material with a Density of 0.2
Then I used a Spot-Light with a linear light falloff, by plugging the "Linear" output of a "Light Falloff"-node into the strength input of the Emission-node.
you can download the blend file here
Volumentric emission shader
point density smoke test
Dynamic Paint particle growth
AN experiment - force field curl clusters