Re: Spark-gap sparks vs. solid-state sparks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Ken,
        I've been following this thread with interest:

On 30 Apr 01, at 11:34, Tesla list wrote:

> Original poster: "Kennan C Herrick by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <kcha1-at-juno-dot-com>
> 
> Antonio (& all)-
> 
> [comments interspersed]:
> 
> On Sat, 28 Apr 2001 21:35:22 -0600 "Tesla list" <tesla-at-pupman-dot-com>
> writes: > Original poster: "Antonio Carlos M. de Queiroz by way of
> Terry Fritz > <twftesla-at-uswest-dot-net>" <acmq-at-compuland-dot-com.br> > > Tesla
> list wrote: > > > > Original poster: "Kennan C Herrick by way of Terry
> Fritz > <twftesla-at-uswest-dot-net>" <kcha1-at-juno-dot-com> > > > I think that the
> cause lies in the inertia of the air that the > spark must > > push
> aside, i.e. heat up, for it (the spark) to advance.  As I > wrote, > >
> that's the same mechanism that allows nuclear bombs to work (and >
> aren't > > we thus in fine company?). > > Humm... I would say that the
> heat is a consequence, not a > prerequisite. > The current starts to
> flow first, and it's the current that heats > the air. Certainly there
> is a positive feedback mechanism once the > air starts to get hot, but
> without current there is no heating. > (I don't see the relation to a
> nuclear bomb, that has nothing of > electrical).
> 
> A consequence, of course; but my point is that the spark cannot
> progress until the heating is accomplished.  That takes time and the
> time exists because of the air's inertia.
> 
> As to the bomb, my tongue was in cheek a bit.  But the bombs do
> critically depend on inertia, as do an infinite number of other things
> in the Universe, of course, including regular bombs.  Inertia holds
> things together long enough for the processes to work: thermal burning
> in the case of conventional bombs and nuclear fission and/or fusion in
> the case of nuclear ones.
> 
> Someone save me from this thesis by (successfully) proposing another!
> 
> > 
> > >...
> > > If my secondary's voltage rises to break-out in, say, 40 cycles 
> > while a
> > > comparable spark-gap-secondary's voltage rises in 2 cycles, then 
> > the
> > > exciting magnetic fields must rise by the same factor, of 1:20.  
> > In order
> > > to get that 20X increase in field rate-of-rise, one needs 20X the 
> > current
> > > in the primary--from 20X the voltage applied.  Of course, that 
> > 20X
> > > current doesn't get applied for very long; not nearly so long as 
> > my ~7 ms
> > > per spark for example (Otherwise, coilers would be moving from 
> > California
> > > in droves.).
> > 
> > I commented before on this question of rate of rise. Remember that
> > the energy transfer occurs in several oscillation cycles (at least
> > one full cycle for coupling coefficient=0.6). If the frequency of
> > the oscillations is not changed, the current and voltage amplitudes
> > are limited by energy conservation, and the number of cycles has
> > little effect on the maximum rate of rise of voltage or current
> > anywhere in he Tesla coil circuit. The visible output of the coil
> > depends fundamentally on the energy available for each discharge,
> > and to a certain extend also on the number of discharges per second
> > (the hot air, or ionized air, theories).
> > 
> > Antonio Carlos M. de Queiroz
> 
> As I see it, with a sufficiently high initial rate-of-rise (probably
> not realizable with normal T.c.'s), merely the first 1/4 cycle of
> primary flux, or part thereof, could raise the top electrode's voltage
> to the break-out level.  If I can do it in 40 cycles and other,
> spark-gap, coils can do it in 2 cycles then some other coil could do
> it in 1/4 cycle, given sufficient primary flux.
> 
> Ken Herrick

It probably is realizable with normal TCs. All it takes is for 
sufficient energy to be transferred in that first 1/4 cycle at the k 
you are working with. That implies that the primary voltage/energy 
store would be *far* larger than for normal operation. If it was a 
cap discharge regime per most of the coils around, a coil which 
normally runs on shots of say, 3J might need 20 - 30J to get to 
breakout that soon. I imagine if this was done, there would be some 
amazing sparking as the rest of the energy store was poured in over 
the next few cycles. I wonder if this had anything to do with a 
report from someone recently who said that they'd pushed their input 
power to a point where the coil first of all started racing sparking, 
and then progressed to smooth operation as input power was further 
increased?

Regards,
malcolm