Hey team!!
SO 
by default the particle helper will pick the assets from here: Babylon.js/assets/particles/systems at master · BabylonJS/Babylon.js · GitHub. For instance when you use “sun” as the particle name it will pick this json:
Babylon.js/sun.json at master · BabylonJS/Babylon.js · GitHub
You can automatically generate a new JSON but configuring your particles systems and then call Babylon.js Documentation
As @Wingnut said you can change where the jsons are located by using BABYLON.ParticleHelper.BaseAssetsUrl
Doc: Use the Particle Helper - Babylon.js Documentation (which can greatly be improved by what I’ve just said here. So if anyone want to help :))