Re: S.S.T.C. "booster"--expert opinions wanted...

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Kchdlh-at-aol-dot-com>

> I have also offered here my opinion as to the reason that s.s.t.c. sparks are
> shorter than ordinary t.c. sparks.  Given the same input power,  a spark-gap
> primary-drive delivers a very much higher initial primary current than can a
> s.s. drive, as is well known.  The resultant flux drives the top electrode's
> voltage much more rapidly toward, and in fact, I contend, considerably past,
> the normal break-out potential before spark break-out can significantly
occur.
> Considerably-past because any spark break-out is very slightly slowed by the
> necessity to heat the surrounding air: that's what causes the "delay"
spoken of
> by others.

Humm... The formation of a spark channel takes nanoseconds at most. 
For usual Tesla coil frequencies, the terminal voltage, at least at the 
breakout instant, is no different from DC. I don't think that the
terminal can
sustain electric fields above the limit for air breakdown for more than,
say, 1 nanosecond, possibly less, before ionization starts to occur and 
the voltage is limited. Sparks propagate at a good fraction of light
speed (easily 10% for lightning).

> So I have an idea as to how to augment the rate of rise and it is illustrated
> in KCH-BOOSTER.  The thought is to add an auxiliary coil snuggled in at
the top
> of the secondary directly below the electrode.  In the course of voltage
> build-up, that coil will develop so many volts per turn, just like the top
> turns of the secondary itself.  Choose the quantity of turns to develop
> something like 10 KV just prior to (un-boosted) spark break-out.
> 
> Into the top recess of the electrode (presumably a toroid), snuggle an
> appropriately sized capacitor--likely an MMC.  

A capacitor that doesn't effectively short-circuit a coil at this point
would have to be quite small. A few pF at most.

> Connect one end of it to the
> toroid and pass the other through a hole in the web of the toroid to a
> spark-gap just below and thence to the bottom end of the added coil.
When the
> voltage of the added coil reaches its near-maximum, the gap is to break down,
> thus connecting the capacitor across that coil.

Ok.
 
> My thought is that at that instant the situation in that circuit is the
same as
> the situation in a conventional primary: capacitor, coil and high-voltage
> source connected in a closed loop.  

But there is no voltage in the MMC capacitor, as it's not previously 
charged.

> Here, the voltage initially resides across
> the coil rather than within the capacitor but that should make no
> difference--the circuit should commence an oscillatory energy-discharge,
> resulting in a burst of magnetic flux in the coil--of significantly larger
> initial amplitude than was previously present due to excitation from the
> primary.

The energy to drive these oscillations will come from the energy stored
in the self-capacitance of the small coil only, with a little from the
current in the coil if the gap fires out of a voltage maximum. Little
energy only. 

> That flux-burst ought to act to induce a correspondingly-large flux burst
into
> the top end of the secondary, resulting in a boost of voltage of the entire
> assembly above the secondary: toroid, capacitor, gap and added coil (the
> capacitor appearing as a near-short-circuit for that voltage pulse).  If that
> turns out to be the case and if my surmise as to the air's thermal inertia is
> correct, then a longer spark should result.

When the gap fires, the short coil will be short-circuited by the MMC
capacitor, and the terminal voltage will suddenly drop a bit, not rise.
 
> You analytical types:  What do you think of this?  Can it be run as a
> simulation?

It can be simulated easily, at least before breakout. If it will be
effective
is questionable, by the reasons that I state above. It may actually
work,
forming a kind of "triggered spark gap", where the starting spark may
trigger
a larger breakout from the terminal. The MMC has no function, unless you
find a way to charge it significantly, maybe from a battery-operated
power
supply inside the terminal. Then, you will have the small coil
triggering
the discharge of the MMC in a strong spark, that may trigger the
discharge
of the terminal more effectively. Who knows?

Antonio Carlos M. de Queiroz