Wanted to point some of you to this page, it's not a perfect ignition source but I this this would be a very good Ram-Jet or something igniter, as it will only produce plasma at the right pressure & I'm guessing larger or smaller diameter of tubing and other components it could be tuned not to unlike the sizing of combustion and tail pipes in pulse jet configurations?
If I'm understanding the write-up and from looking at the images, when air is sucked/pushed into one side then in the middle as it passes the copper pipe and tungsten rod with a tip of fused alumina (sapphire) outer tubing it will create static? or plasma?
http://members.tm.net/lapointe/Pseudospark_Switch.html
Well I'm going to try and build one to see what happens if anything, I think that's going to take me a while yet though
All the best,
Charlie