Spark gaps are very interesting....unfortunately with regards to your work I can't myself input much...I'm at learning how to calculate distributed capacitance of the secondary windings for transient spikes induced back into the primary to get the spark across the gap with a low voltage drive.
It's normally pretty hard to get a low voltage spark to jump a triggered spark gap. One approach I've used is to employ two parallel gaps, one with an adequate voltage to jump the gap and the other gap positioned within the first gap's arc sheath. A high voltage spark consists of positive ions, while free electrons are moved outwards by the Lorentz Force. These free electrons form a conductive region.
Another way to do it is to use Longitudinal Energy to pump the low voltage current. The LE is produced by a diode T plug circuit:
(https://s20.postimg.org/x32mb1u0d/Diode_T_Plug.gif)
Here's a picture showing the charge pump effect:
(https://s20.postimg.org/c7gbzsxt9/Longitudinal_Spark2.jpg)
The colored spark is an example of a Z axis magnetic interrupter. The T spark goes right through the primary spark's magnetic field around the rod gap, to or from the upper external electrode, depending on polarity. It's possible that a physical magnet could be positioned close to the top spark. The dark mass is a chunk of resistive charcoal from a burnt 2 by 4, with a central hole which allows it to be slipped over the electrode rod.
I imagine there are other ways to use, or produce the LE spark, rather than with the diode T plug.
Otherwise, I feel that a coil's distributed capacitance is very important. While this factor is parallel to the coil's circuit, the capacitance of a portion of the coil would be in series with the rest of the coil. Capacitance in series with an inductor is what produces the Plasmoid, and this may be responsible for the occasional ballooning of a TC streamer.
Thanks for posting and good luck with your experimenting.