Forcefield system, how does it work?

Im trying to create a Forcefield material which show hits from projectiles. I found multiple videos where someone shows what i am looking for:

[Forcefield example] (UE4 Force Field System Preview - YouTube “Forcefield example”)

[Forcefield example] (Star Wars EaW FoC [Unreal Engine 4] - 3 (Shield) - YouTube “Forcefield example”)

Can someone explaine me how they did that?