Particules moving on surface of mesh

Hello dear Artists !

I am trying to achieve an effect I have seen on this video:

I cannot understand how the particles are staying on the surface of the mesh and the color gradient of particules.
The author of this video do not reply, and I am sure some of you are a “particles specialist”.
Can you help me on this point ?

Thanks a lot

Mabe something like this with force fields. I don’t know how to make color gradient particles.

IMO, the particles neither flow on the surface of the mesh, or are coloured. I’ve tried a quick setting that gave me the following result:

As I said, that’s a quick test, and the result can be tweaked, and then refined during compositing (fog glow and stuff), but it kinda shows, that the effect can be achieved by just emmiting particles from inside an object (and setting that object to collision in physics tab), giving the particles an emmiting material, and setting the object material to be glasslike, with a colour controlled by a texture.

Hope this helps.