Well, there's no shader in the conventional sense, it's all built into the CoronaVolumeGrid object. I've had it working fine, just need to select the correct data to use to drive the Emission, Temperature being the most likely one to use (the hotter it is, the more it glows). Then adjusting the Scale and maybe the gradient in the Grid mapping if you want to adjust the colors and how they fade off. Of course you could drive it using Density, Velocity, or any of the other parameters too, but Temperature is the one that would work best for Emission.