How can I make a luminescent gas cloud, similar to the one shown in the picture below (labeled "Trapped Atoms")? Thank you.
Simple Sphere with Emission as a Volume would be sufficient. We will use for both methods mostly the same setup. Gradient Texture > Color Ramp > Emission shader.
Color Ramp will control color and smoothness. Emission > Strength... Strength.
They will look like gas spheres and emission will not affect other meshes.
This ones will affect meshes with light.