TC electrostatics / question

I've been following the thread on electrostatics and finding it
fascinating, Richard H is certainly pushing the envelope. I have
a question related to electrostatic phenomena. 
  What would happen if the discharge toroid was insulated, i.e.
coated with 1" of polythene or similar all round? Would this
increase capacitance of the toroid due to using a high dielectric
material? Would it also raise breakout voltage, thereby
conserving more energy in the system and increasing ground
current? Could this method be used to prove / disprove the "ion
cloud" hypothesis?
  OK it was more than one question, and I would try it myself if
my TC wasn't 100 miles away :(
Any Ideas?

Steve Crawshaw