Concentric spheres- an hypothesis

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "K. C. Herrick" <kchdlh@xxxxxxx>

David Thomson's mention of John Freau's concentric spheres, 
in  "Magnetically controlled spark gap for Wireless Transmitter" 
posted yesterday, piqued my interest.  In case it hasn't been 
analyzed before, here's Herrick's Hypothesis as to how they work:

The inner sphere is connected to the top of the coil; the outer 
sphere "floats".  The capacitance between the two spheres is much 
larger than the capacitance to space from the outer sphere.  Thus, as 
the charge on the inner sphere builds up during a cycle, the charge 
on the outer one will also, to almost the same degree, through the 
capacitive reactance.  But the radius of curvature of the inner 
sphere is (necessarily) smaller than that of the outer one.  Absent 
the shielding effect of the outer sphere, the inner one would break out first.

At the instant the outer sphere starts to break out (to space), its 
potential diminishes, and the inner sphere--already with a charge on 
it exceeding its capability absent the shielding--breaks out to the 
inner surface of the outer sphere.  Then, again instantly, all the 
charge on the inner sphere becomes transferred to the outer surface 
of the outer sphere--since like charges repel and thus "strive" to 
occupy the surface that allows them to be the furthest apart.

The outer sphere's surface then contains charge substantially in 
excess of that required for breakout and the incipient spark is 
thereby substantially given a double whammy, so to speak (and thanks 
for that to cartoonist Al Capp of fond memory).  What we have here is 
nothing less than an >>electrostatic magnifier<<.

One could even imagine three concentric spheres, the outer two 
floating, giving a triple whammy.  It does seem to me that 
concentric-surface configurations might well become the electrodes of 
choice in the future.  And in fact, they might not need to be 
spherical: concentric toroids might do it--either one within the 
other or one surrounding the other.  Or a ring of spheres surrounding 
a toroid or another sphere, for instance.

When & if I get my latest (and last!) configuration going, I shall 
check it out for sure.

Does this seem plausible?

And the above reminds me of the conjecture I'd posted some time 
ago.  Conventional wisdom says that sparks from a disruptive coil 
tend to be longer than those from a solid-state coil, other 
characteristics of the coils being comparable.  I conjectured that 
that was because of the differing rise times of the drives from the 
secondary: the energy into the top load is delivered during the first 
cycle or two in the disruptive coil while that delivered by the 
solid-state coil occurs over many more cycles.  Thus, for breakout 
from the same top load, the voltage rise-times must be substantially 
different.  The spark requires time to break out; I found a reference 
that indicates that a spark takes around 50 ns per inch to propagate 
in air.  If during such time the voltage rises higher in the one 
case, then the spark should become longer.

So what think you of that?

Ken Herrick