Ok here is my progress 
Instead of calling the BuffPulsarRadiation by the ability I called BuffPulsarRadiationDamage directly. And it crashes again. Next i increased delayTime of my damagebuff from 0 to 10 and now after 10 secounds crash.
Next step i call again BuffPulsarRadiation from the ability and BuffPulsarRadiationDamage from BuffPulsarRadiation, as it was before. Again after 10 secounds crash.
which brings me to the solution that my BuffPulsarRadiationDamage entity is the true problem.
I also tested instead of using
buffInstantActionType "ApplyBuffToTargetsInRadius"
this one
buffInstantActionType "ApplyBuffToTargetsAtOrbitBody"
as you said before.
i switched between the damageType "PHYSICAL" and damageType "ENERGY"
allways the same effect : sins crashes and no error message 
I also added a weapon effect to BuffPulsarRadiation where a sound is played. The sound plays correct and after 10 secounds crash again.
I hope this is no hardcoded thing that abilities on stars cannot call a buff with DoDamage inside. 