[NicoR44]

That's it!!

Just use a low poly mesh sphere

[tom]

So the problem was in multi-poly emitters?

No, it's about the unnecessary amount of faces of your emitter geometry. A typical sphere emitter is possible with tens of faces. Hundreds or thousands of faces will end up with such artifact.

[tom]

when is a sphere complex?

Sphere is complex if it has a lot of faces.