Re: Secondary Q

[paul-at-xxxxxxxxxxxxxxxxxxx (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Terry Fritz wrote:

> As you note, our voltage amplification is by impedance
> transformation rather than pure resonant ring up.

Indeed,

Kennan C Herrick wrote:

>  Resonance, even...who needs it? 

It's the coupled resonance that provides the mechanism for
the impedance transformation. Off hand I can think of no other
way of transferring all the energy from a large capacitor to 
a small capacitor, except perhaps by pulling apart the plates
of the large capacitor so that it becomes the small capacitor!

> Q?...who needs it? 

Well if the secondary Q is above about 50 or so, it's not going
to be a major determinant of efficiency for disruptive systems -
so long as the system is well tuned and properly coupled, the
energy is not going to be sloshing around for enough cycles for
the Q to matter too much. The primary Q and gap losses are likely
to be the main issues.

CW coilers will however be justified in worshiping Q factor, as in
this case the resonant energy storage of the secondary is the 
mechanism by which the voltage is built up over the many cycles
of a CW burst. Moving from a lossy sonotube to a high Q HDPE would
make for a factor two or more increase in output voltage for a 
given CW power.

> Disillusioned in California,

No need to be Ken.  In my opinion there is plenty of room for
improvements in performance. Primary gap loss could be the main
one, but I know nothing about spark gaps so I'll say no more.
Another area is that of finding secondary and topload geometries
which exhibit the smallest possible capacitance. (In this
respect I favour the half wave bipolar with the two coils
well separated and at placed at high elevation.)

John Freau wrote:

> (defining efficiency here as spark length vs. input power. 
> I know this is not a true engineering definition of efficiency,
> but it's a useful measure I think).

I'd avoid the use of the word efficiency, but I do agree that
the spark length vs input power is an excellent overall measure
of performance.

In this respect I'd quite like to gather some statistics in order
to establish what the state of the art is in terms of this measure.
If coilers wish to send me the following info, I'll be glad to 
plot the results on some scatter diagrams,

 Input power:
 Max spark length:
 BPS:
 Peak primary tank voltage:

(disruptive coils only), send to tesla-stats-at-abelian.demon.co.uk 

> Filled with wonder, hope, and coiling optimism in NJ,

Well said!

Regards,
--
Paul Nicholson,
Manchester, UK.
--