[Prev][Next][Index][Thread]

Re: Gap Dwell Times (formerly: Beating Solved)

Tesla List wrote:
> 
> >From sroys-at-umabnet.ab.umd.eduTue Oct  8 21:56:57 1996
> Date: Tue, 8 Oct 1996 09:40:42 -0400 (EDT)
> From: Steve Roys <sroys-at-umabnet.ab.umd.edu>
> To: tesla-at-pupman-dot-com
> Subject: Re: Gap Dwell Times (formerly: Beating Solved)
> 
> On Mon, 7 Oct 1996, Tesla List wrote:
> 
> > >> > A lot of folks think the primary rings are transferred to the secondary!
> > >> >  Well,.... yes and no.  If you do not quench your primary circuit arc
> >
> > <HUGE SNIP> <HUGE SNIP> <HUGE SNIP> <HUGE SNIP>
> >
> > >could avoid the reflection loses in the original spring.  We seek to
> > >allow the spring to hit with max energy, but stop it at that point and
> > >not give any rebound energy back to it.
> > >
> > >In an over-coupled, and, or, under-quenched coil.  All the energy from
> > >the capacitor which can be magnetically coupled is in the secondary after
> > >the end of the first 1/2 oscillation in the primary.  Immediately
> > >following this, the secondary is pumping some of its valuable, just
> > >received, energy back to the primary, if the gap is still conducting.
> > >
> > >Precision quenching is what I'm looking for in the H2 thyratron
> > >experiments.
> 
> To Richard Hull (primarily) -
> 
> I went "straight to the horse's mouth" ("Vacuum Tube Tesla Coils" by the
> Corums) and now I'm confused.  In appendix IV, they discuss coupling,
> spark duration, and output voltage, and they come to the conclusion that
> "The primary energy will be transferred to the secondary in one half of a
> BEAT period....In spark transmitters, it is desireable to quench the
> primary spark when the energy has been transferred to the secondary."
> 
> Their graph of secondary voltage vs. spark duration (fig 8, appendix
> IV) also points to a theoretical ts = 1/(2 * deltaF) primary spark
> duration for "optimum spark".
> 
> This relationship is what I've been trying to get across, but this
> doesn't seem to be what you're saying.  Are you saying that the gap should
> be quenched after only the first half-cycle of primary oscillations at
> the natural free-resonant frequency?  If so, then I'm confused and I have
> more questions about the applicability of the Corum's findings in appendix
> IV.  If you are  talking about quenching the gap after one-half cycle of
> the BEAT frequency, then we've been saying the same thing.
> 
> Steve Roys.

Steve,

Language often fails us.  I fear this is one instance or case in point.

  The beat frequency, the resonant frequency, the natural period of oscilation all are 
the same thing.  The capacitor in the primary tank discharges into the primary coil when 
our switch (the arc) closes the circuit.  100% of the capacitor's energy is dumped over 
the first half cycle of the primary ring up or what "would" be the primary ring up.

  During the first quarter cycle (90 degrees), the voltage in the primary coil is 
building up.  But, due to inductive reactance, the current maximum in the coil is delayed 
by 90 degrees after the voltage maximum!  This is a full 180 degrees into the primary 
voltage ringup and coincides with the first zero crossing of the voltage waveform after 
initial rise.  Only when maximum current flows in the primary will the magnetic field be 
fully expanded and all of the primary magnetic energy ready to do work.

This is the ideal point, according to the Courms, much theory, and some common sense, 
that we must make the entire primary circuit totally disappear, electrically.  This can 
only be accomplished by opening our switch. (quenching the arc.)  The primary can't ring 
or inductively react with the secondary if there is no path for current flow.  Thus, no 
deleterious beating between the two systems occurs and 100% of the transfered magnetic 
energy (limited by the coefficient of coupling) is received and used by the secondary 
resonator.

In theory, if not quenched, the secondary will ring up and then as its field collapses in 
on the secondary, it will also envelop and be coupled back into the primary which itself 
is ringing (if we don't quench), but out of phase now.  The two will conflict and the 
energy sent back into the primary will be partially absorbed and lost to the secondary 
duuring the primary's second, third, etc, rings.  In general, with only 3-5 rings, the 
average coil has shot its bolt after the second primary ring anyway.  Subsequent energy 
transfers are to be considered as "also rans" and don't contribute anything noticable to 
the output.

Richard Hull, TCBOR