How do I set point density node for smoke?

I’m trying to make this animation , I’m using particles from an emitter to create the smoke and force fields to give them the direction I want .

The problem is I’d like to shade the smoke as it was very much heated in the center , where the particles flows is , so it looks pretty much like a lighting bolt .

I knew of a function named voxel data in the textures that would allow to achieve this result , but I can’t find it in the new version of blender . Does anyone know what I should do , once I got the smoke from the particles emitter ?