Spin,
It's all experimental. My hybrid rod vic works and makes gas. ...now, for example, I added three iron wire spiral chokes in series to the negative side with an iron powder epoxy core and it bumped up to 2.2kv at 12v with 10ma. I'll be trying the same rod type set up with an iron wire secondary soon enough and let ya know, dude. The iron wire has an effect with many fewer turns and length of wire used compared to copper, that is well proven to my satisfaction. Looks like I'll be using the hv probe from here.
kb