magnifier vs. classic tc (magnifier modeling)

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: magnifier vs. classic tc (magnifier modeling)
From: Tesla List <tesla-at-stic-dot-net>
Date: Wed, 18 Mar 1998 22:38:05 -0600
Approved: tesla-at-stic-dot-net

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From:  Antonio C. M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent:  Wednesday, March 18, 1998 12:15 AM
To:  Tesla List
Subject:  Re: magnifier vs. classic tc (magnifier modeling)

John Freau wrote:

> Next, a secondary with a higher inductance of 5mH (but of the
> same physical dimensions as the 1.5mH sec), was installed, to
> verify that the effective coupling would increase as the secondary and
> extra coil inductances became more similar.  Tests were done using
> the 13mH extra coil, and also using a 20mH extra coil.
> 
>     Driver k            Effective k (meas)    (calc)     Lr/Ls      Quench
>                                    (extra coil)
> 
>   .51  (1.5mH)           .18  (13mH)           .16      8.7:1    4th notch
> 
>   .45  (5mH)              .22  (20mH)           .20       4:1     5th notch
> 
>   .42  (5mH)              .29   (13mH)            .22      2.8:1    6th notch
> 
> It can be seen in the table above that as the ratio of
> inductance between driver and extra coil decreases, the driver k
> and the effective k become more similar.  Some of the differences
> between the calc and measured k values may be explained by
> losses in the system, however the last entry seems anomalous.
> More work is needed.  Effective k values were measured by
> observation of the beat period relative to Fo.

I would attribute the crescent deviation of the measured k from the predicted
k by the formula k=k(driver)*sqrt(L2/(L2+L3)) to the lowering of the resonance
frequency of the L2C2 combination. Small losses don't change the beating periods
significantly. Did you verify the presence of amplitude modulation in the
secondary voltage waveform -after- the quenching of the spark gap, or irregularities
in the beating waveform before the quenching? This would indicate that the secondary
tank L2C2 is becoming significant.

Something that I would like to see (maybe not practical, but...): 
Increasing the size of L2 and decreasing the size of L3, there should exist a 
point where L2C2=(L2+L3)C3. At this point beatings shall occur in the
secondary-third coil system after the opening of the spark gap. In this
condition, periodically all the energy will be concentrated on C3 only.
If C3 is only the small self-capacitance of a small L3 coil, the voltage
magnification can be significantly higher than in the low-L2/high-L3 condition,
where C3 includes the higher self-capacitance of the L2+L3 combination.
 
Antonio Carlos M. de Queiroz
http://www.coe.ufrj.br/~acmq