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Em 23/08/2018 11:12, Daniel Kunkel escreveu:
Antonio,
I understand the first part of what you are saying with the energy transfer
(which I understand to come from the very tight coupling of L1 and L2).
This is a reason, allowing faster energy transfer, but there is also the
effect of the shape of the waveforms if the
secondary coil is correctly tuned.
Precisely: In a conventional Tesla coil the primary voltage falls with a
cosinusoidal envelope, while the secondary
voltage rises with a sinusoidal envelope. In a Magnifier the
corresponding envelopes are squared. This reduces the
amplitude of the primary current in the initial part of the energy
transfer, reducing the loss in the spark gap.
More energy is then transferred to the top load.
However, when we look back several decades at what Tesla Coil hobbyist did
from the time of Tesla's death until the 70's or 80's, many of the
secondary coils had horrible aspect ratios (small diameter and VERY tall,
which we now call candlesticks). The result was poor performance, and were
designed completely opposite of Tesla's CSN coils with with aspect ratios
of 1:1 or 1:2. Today we seem to have settle on 1:3 - 1:4 for our coils. Is
that better, or a compromise?
"Candlestick" coils may have too low coupling with the primary,
resulting in many cycles for energy transfer and
greater loss. Too short coils don't have enough insulation.
But to your statement, " Without losses considered the maximum output
voltage with two or three coils, with the same primary capacitor and total
load capacitance, is the same." I have to ask, if that is true, then how
many turns of wire is needed on the final resonator (L2 or L3)? How much
inductance is needed in any coil to produce high voltage? As a community I
think we have settled on 1,000 turns (+/- 200 turns).
The voltage gain of a Tesla coil or a Magnifier can't exceed the square
root of the ratio between the primary and
secondary capacitances, due to energy conservation: 0.5*Cprim*Vprim^2 >
0.5*Csec*Vsec^2.
The inductances of the coils are a consequence of what can be built with
reasonable capacitances.
In a Tesla coil the tuning relation must follow Cprim*Lprim = Csec*Lsec,
and so the voltage gain is
also the square root of the ratio of secondary to primary inductances.
Normal primary coils with a few turns have
inductances in the tens of microhenrys. A gain of 30 puts the secondary
inductance in the tens of milihenrys.
Reasonable geometries for air-core coils really result in around 1000
turns for this range of inductances.
So if we continue to stick to these aspect ratios and parameters and employ
them in the typical magnifier setup, then yes, I would expect performance
to be similar. But I believe with magnifiers (L1, L2, and L3) can and
SHOULD be constructed to 1:1 aspect ratios. I realize you have a LOT of
real world magnifier experience...I hope to get there too some day!
I don't have a lot of practical experience with magnifiers, but I know
their theory. I have built just a few low-power variations to
check the theory, that worked precisely as calculated. 1:1 ratio seems
good for L2. L1 must be flat or wider to result in adequate couplings
with L2.
L3 can be short, but enough inductance is best obtained with more turns
than with wider coils. The lenght is determined by
insulation.
Here is an interesting video. That green pole on the left is the secondary!
Now I believe this one was constructed for this experiment and not made to
produce the normal streamers...but still interesting.
https://youtu.be/A6Tc6Hj4cas?t=1m37s
Seibt coil, a standing wave demonstrator. Note that the long coil is a
kind of third coil of a magnifier.