Re: Why Secondary Q Matters

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

Hi Malcolm,

I agree the secondary Q is very important.  I would imagine that
the Q of my old research coil was high enough despite the 1500
turns of 28 awg wire.  I didn't actually measure it, but the coil was
4.2" diameter x 23" tall, topped with the 5" x 20" toroid (in an 
early configuration).  It seems that the Q doesn't need to be 
super-high, but just high enough to not create excessive losses. 
It's a balancing act as you've said years ago (a balancing act of 
primary gap losses vs secondary losses).  My coil may not have
met your requirement of 5 skin depths though.

Cheers,
John


>
>      I'm not a great fan of matching-secondary-impedance-to-spark 
> theory because the impedance of the spark is in fact going to be 
> determined by both by available energy to feed it and the type of 
> spark it is (air or attached). (I should qualify that by saying that 
> the pressure, temperature, mositure content and molecular content of 
> the gas must also be a determining factor)
>     In the first case, the spark impedance is relatively high 
> (witness the relatively high loaded Q of a system producing 
> airstreamers) and in the second, rather low (the loaded Q of the 
> system has dropped into the dirt). This is why a large terminal 
> capacitance makes loud bright arcs that we all love. One might infer 
> from that that the secondary is doing most of the delivering to the 
> air streamers and the terminal to the arc, and we want the streamers 
> to generate the long stretch prior to a connection with on object 
> being made.  The scope waveforms strongly suggest this is what occurs.
>