Hi Mexpex, I saw you may want to add effects to other thrusters. I just had a few idea for those.

For Atmospheric give it an afterburner effect. Use a bit of blue and orange and add shock diamonds/cones.

Here is an image link for example (This is a bit long/overkill. It is a SR-71 engine so turn it down form this):
https://upload.wikimedia.org/wikipedia/commons/thumb/6/60/J58_AfterburnerT.jpeg/300px-J58_AfterburnerT.jpeg

Maybe also add a blur effect from the heat caused by the exhaust (useperlin noise? or use a modified safe zone effect. Not sure how particles work in SE but you get the idea.).


As for Ion, real life Ion engines are boring and lame so maybe go for a sci-fi look. Have little bits of blue dust like particles fall of the "flame".