Hi Tom,
I have a few links to the origine of that coil
And the why to use that:
pay attention to the air intake of the gasifier, the color of the glowing changes when the water steam enters, the engine revs up from the hydrogen formed in the reduction with the glowing carbon.
This is a clip to demonstrate how far the red glowing zone reaches in this simple build with an horizontal nozzle.
I keep my charcoal small sized, bamboo charcoal, then that hot zone stay’s in limits