My quick 2 cents worth here - I looked at the Han patent, amongst others, a few years ago (waterfuelcell org AU) but it took a while to connect the dots...
Stainless Steel forms a very very thin Chromium Oxide dielectric layer (thats what makes it stainless) - the thinner the better, refer to semiconductor physics for more information. ALSO, Dr Pollack, University of Washington, has an excellent 1 hour presentation that is well worth the time spent viewing it several times. AND, high voltage "arc over" has a "hold-off time," it doesn't happen instantaneously. BUT, getting it all just right is a bit of a task to say the least. HOWEVER, nearly anyone can make anything work at least once; the trick is to make it happen reliably every time over the spectrum of environmental and other changes.
THEREFORE, Mr. Meyer may have progressed to his "water spark plug injector" to ease the tuning and eliminate some of the variables.
Have a good one!