Re: [TCML] Solid state efficiency, was: mini Tesla coil specs

[DC Cox <resonance@xxxxxxxxxxxx>]

Bill Wysock was doing 9 x sec length, but Rich Hull holds the record with 13
x sec coil length in a magnifier configuration.    He had an enormous two
stage topload that was approx 1`0 ft in dia!

All of these racing sparks are caused by a single failure mode -----
overcoupling!

Dr. Resonance




On Fri, Nov 13, 2009 at 8:18 AM, Steve Ward <steve.ward@xxxxxxxxx> wrote:

> Hi Ken,
>
> It sounds like our intuitions about spark growth agree.  I convinced myself
> that the faster energy rise was better because you spent less time wasting
> energy making little corona on the rising edge of the voltage rise.  What
> led me to believe this was that the secondary voltage in my comparison test
> was essentially the same (simulated, not measured), and the spark length
> was
> the same, but it took less time (and thus energy) to make the spark.  I
> doubt that our resonator drivers will ever be "too fast" for spark
> propagation.  One thing to watch for would be exciting those nasty
> transmission line modes on the secondary, which seem to cause the racing
> sparks, etc...  Interestingly, i believe it is because the SS excitation of
> the system is "slow", that you can build small DRSSTCs that really put out
> huge sparks with out much fuss.  Some small coils have produced spark
> lengths exceeding 5X the secondary winding length, my best has been about
> 4X
> getting 45" sparks from an 11" tall secondary winding.  This is something
> ive never seen with a SGTC, usually racing sparks would just destroy the
> secondary if you attempted to cram that much power into one.
>
> Steve
>
> On Thu, Nov 12, 2009 at 10:57 AM, Ken or Doris Herrick <kchdlh@xxxxxxxxx
> >wrote:
>
> > Steve Ward writes, "[I] think energy transfer time to the spark is very
> > important" for maximizing spark length.  I agree and repeat here an
> opinion
> > I posted a few years ago:  As compared to a solid-state coil, the
> relatively
> > much-higher rate-of-rise of the initial half or whole cycle from the
> abrupt
> > shot of energy thru a spark-gap will allow charge to be crammed onto the
> top
> > electrode before the spark has a chance to proceed very far.  A research
> > paper I have a copy of has found spark propagation in air, measured over
> 1
> > inch of distance, to require about 50 ns of time.  That extrapolates to
> > about 20 inches of travel per microsecond.  So with a high rate of
> > voltage-rise, more charge can be applied to the electrode than can bleed
> off
> > through the spark during its first several inches of travel.
> > Ken Herrick
> >
> > [snipped]
> >
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