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Re: Arc length vs pwr
Tesla List wrote:
>
> > >> Subject: Re: Arc length vs pwrRe: Arc length vs pwrRE: Arc length th vs pwrRe: Arc length vs pwrRE: Arc length vs
>
> >From hullr-at-whitlock-dot-comWed Oct 16 22:32:49 1996
> Date: Wed, 16 Oct 1996 10:25:20 -0700
> From: Richard Hull <hullr-at-whitlock-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Arc length vs pwr
>
>
> big snip
> > >>
> > >> Any theories as to where the energy goes that is lost due to
> > >coupling?
> > >>
> > >> -GL
> > >
> > >
> > >Greg,
> > >
> > >I would image that any flux lines that are not common to both coils
> > >are
> > >just lost, provided they do not couple to something else nearby in
> > >either the expansion of collapse phase of the primary magnetic energy
> > >pulse. (ground, effective shorted turns, etc). Most of this magnetic
> > >
> > >energy would collapse back in on its source coil. (the primary). If
> > >we
> > >open it though, (quench the spark), the voltage induced in it is never
> > >
> > >forced to do work and is lost. Those flux lines common to both the
> > >secondary and the primary would induce voltage in the secondary as
> > >well
> > >as the primary. Some small amount of energy would most likely radiate
> > >away as RF obeying the inverse square law.
> > >
> > >Richard Hull, TCBOR
> > >
> > This is just a thought, but wouldn't any energy in the
> > primary tank that wasn't utilized in coupling to the
> > secondary simply remain in the primary as reactive power
> > creating a "standing wave" on the next primary half cylcle? I know what
> > I'm trying to say, I just don't know
> > if I'm saying it right <G>
> >
> > Mark Graalman TCBA#1399
>
> Mark,
>
> This is a good thought. The reactive energy recaptured in the primary
> coil from the collapsing flux would not do anything though if the primary
> circuit were open. (arc quenched, gap deionized) In short, it got "all
> dressed up and has no where to go" Yes there is some capacitance in the
> primary coil and yes it could ring up to some super high frequecny as a
> separate resonator coil, but the bulk of the energy just disappates into
> space as lost magnetic energy. We certainly don't see it doing any work
> in the coil system. (Again, all of this assumes we did quench flawlessly
> and on time!)
>
> Richard Hull, TCBOR
Richard, Mark and all,
Hmm.... I would suggest that the "on-time, flawless quench" should occur
at the point where we have transferred ALL the primary's available
energy to the secondary, and NOT before. For a given "bang", this point
will not reached until the end of the first beat, when the primary
energy is 0, and ALL available system energy has been transferred to the
secondary tank circuit. The Corums, Duane Bylund, and various PSPICE
simulations seem to be correct!
It's taken me quite a while to fully grasp a unique property of
loosely-coupled tuned resonant circuits:
- During a given beat, the energy "flow" is ONE-WAY!
Although there's no "brief" explanation, Steve Roys' previously posted
coupled-pendulum analogy IS an appropriate mechanical analog.
When the gap first fires, and for the entire duration of the first beat,
energy transfers only in one direction - FROM the primary tank circuit
TO the secondary/toroid tank circuit. Each primary half-cycle will _add_
to the energy building in the secondary tank. This one-way transfer
process continues until no more primary energy remains (at the end of
the first beat).
If we quench prior to this, irrespective of how precisely, we'll simply
dissipate, or strand, that portion of the "bang" that hasn't yet
transferred, needlessly reducing ouput energy. Where the stranded energy
goes is not very important - whats important is that it WON'T go into
helping make bigger, hotter sparks! Although we can quibble about
voltages vs arc lengths, higher _output_ power means longer sparks!
At the start of the second beat, the direction of energy tranfer
reverses. ALL the energy in the system now resides in the secondary
tank. From an efficiency standpoint, this _should_ be the point of
optimal quench. If we let the gap continue firing, the secondary now
begins to unidirectionally transfer energy back into the primary, each
half-cycle further reducing output. This process continues, as long as
the gap fires, for the _entire_ second beat! The process reverses again
for the third beat and so on, assuming there's still energy cycling in
the system.
Mark, you've got the right idea, if not the precise wording! For
example, if k=0.2, 80% of the primary flux NEVER intersects the
secondary. However, this energy will be lost ONLY if we force the quench
too soon! Assuming we let the gap continue to fire, almost _all_ of this
energy gets "recycled" by reverse-charging the primary cap. The
re-charged tank cap then provides energy for the the next
expansion/contraction of primary flux. During each half cycle, the 20%
of flux that DOES link to the secondary transfers 20% of the remaining
primary energy to the secondary tank circuit. After about 5.5
half-cycles, ALL of the primary's energy will have been transferred to
the secondary (less gap/other losses). Barring premature breakout from
the toroid, the BIG energy loser in the system is still the gap.
However, quenching too soon will needlessly worsen coil losses.
As usual, flames, catcalls, and overripe fruit are readily welcomed! :^)
Safe, and optimally quenched, coilin' to ya!
-- Bert --