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Re: Gap Dwell Times (formerly: Beating Solved)
Tesla List wrote:
>
> >From sroys-at-umabnet.ab.umd.eduThu Oct 3 22:24:20 1996
> Date: Thu, 3 Oct 1996 09:57:58 -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 Wed, 2 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
> > quickly enough, yes! If you quench the arc at the first zero crossing of
> > the primary volatge peak, no!
>
> Another analogy I was thinking about was an experiment with a system of
> coupled pendulums I think I remember seeing. One pendulum was set in
> motion (the "primary") and was allowed to transfer it's energy into
> another initially stationary pendulum (the "secondary"). The first would
> lose amplitude while the second would gain amplitude (coupling/energy
> transfer), until the first pendulum was essentially stopped and the second
> was swinging at it's maximum amplitude ("fully rung up"?). If you let
> things progress, the second pendulum would transfer it's energy back into
> the system and the first pendulum would start swinging again ("back talk"
> or "inductive dance"). They would continue transferring energy back and
> forth in this manner until a pendulum was removed (the gap was quenched)
> or friction (resistance) ground everything to a halt.
>
> If you removed (quenched) the first pendulum before it hit it's first
> energy minimum, then there would still be energy left to transfer and the
> second pendulum would not be swinging at it's maximum amplitude (quenching
> too fast). If you let things progress for a longer period and allowed the
> pendulums to couple and recouple energy back and forth (poor quenching),
> then the frictional (resistive/radiative/etc...) losses would damp the
> oscillations and the second pendulum would never be "ringing free" at it's
> maximum possible amplitude. But if you removed the first pendulum when it
> was at a standstill (first zero crossing of the primary beat), then all of
> it's energy would have been transferred to the second(ary), which would
> then be swinging at it's maximum amplitude free of any influence from the
> first.
>
> Taking this analogy further and posing a question - if you try to remove
> (quench) a pendulum that's still swinging wildly , you will have a lot of
> excess kinetic energy (current) left over to deal with and dissipate. At
> it's first beat minimum, there is essentially no kinetic energy and there
> would be no problems with any excess energy left to dump. Comparing this
> to a coil, has anyone investigated "precision quenching"? It seems that
> it would be a lot easier to quench the gap at the exact time that the
> primary energy has been completely coupled over to the secondary. At this
> time, there would be minimal current circulating in the primary to worry
> about and quenching would be a "simple" matter of getting the gap out of
> the circuit before the secondary coupled energy back into the primary.
>
> Steve Roys.
Steve,
Good thoughts, but a bit wrong. Sorry. Once again, the linkage of
mechanics to electrical activity somewhat fails us. The coupling of the
pendulums of which you speak is extremely loose. In our magnetic
scenarios we are much more tightly coupled than the mechanical analogy.
Next, The capacitor dumps all of its energy in the FIRST CYCLE ONLY!
The other cycles (damped oscillations) are just feedback energy between
the cap and inductor as they swap left over or rebound energy from the
first hit, back and forth. A better analogy for this would be a spring
under extreme tension. When let go, it slams with all and maximum energy
into the other end of itself. Some of this energy is reflected back and
the spring oscillates for a second or to. If we could stop the
reflection energy by absorbing it all (like just maximizing the magnetic
field from the first pulse and having it collapse onto the secodary), we
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.
Richard Hull, TCBOR