I managed to create quite a good looking fire particle system last night.I added shimmer,smoke,embers,orbiting embers and the fire itself.I am quite pleased with the result but the fire emmiter itself is weird it's kinda rough up the edges and especially the top and the bottom and kinda destroys the particle system quality.Is there way I could fix that?

I attached a link which have 4 screenshots,use the arrows to surf along them.