RE: Who needs a quenching gap ?

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

Original poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com> 

Hi Finn:

I don't see how any of the simulation models that I'm aware of can predict
the quenching of a gap.  The gap models that Terry and I use have a
simplistic, predetermined "on" or quench time determined by a one-shot timer
(the actual time value is a parameter of that one-shot, you have to
double-click on it to see the pulse width or change it).  While the period
of the notches is easily simulated and predicted if pri-sec "k" is known,
which notch quench actually occurs at on a real gap is a function of gap
geometry and other poorly understood factors.

I couldn't see how you achieved the single gap configuration on your RSG.
I'm also a firm believer in the loss-benefits of a single gap.  How was that
done?  And congratulations on some drop-dead gorgeous construction!

Regards, Gary Lau
Waltham, MA USA

 -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent:	Thursday, December 07, 2000 6:23 PM
To:	tesla-at-pupman-dot-com
Subject:	Who needs a quenching gap ?

Original poster: "Finn Hammer" <f-hammer-at-post5.tele.dk> 

Gang!

Today I finally managed to get a scope trace off the new RAT-coil under
streamer loading.

This was particularly satisfying, since it confirms the Microsim based
preliminary design effort, which predicted a clean 2nd. notch quench.
This was recorded at 100BPS, about 1 meter streamer length.

http://home5.inet.tele.dk/f-hammer/ringdown.jpg

Horizontal=50µS/div
Vertical:5kV/div

Since the gap is a SRSG with onely one gap in operation, and should
therefore be a poor quencher (but possibly a "low losser") this picture
tells, that this coil is quenching the gap very well.

I believe it is possible to determine the coubling from this trace, how
is that done?

The coil is really just thrown together along the proven R.Quich
guidelines 1000 turns, 1:3 dia/length (although it is a fine spacewind
on threaded form). So the impedance match btwn streamer and coil is not
precise. Zcoil/Zstreamer= 1.6. I have tried to find a way to meet this
match, and if anyone is interested, we could talk more about this
subject. According to this work, the perfect impedance match is met,
when the toroid is arounf 10pF. I can hardly imagine that this would
make the coil perform any better than with the present 32pF . I have
never managed to create a model of a coil, that quenches at the first
notch, so perhaps 2nd. notsh quenching is natural, in some sort of way.

Comments?

Cheers, Finn Hammer