Re: Who needs a quenching gap ?

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

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

Oh, And about the single gap:

There are 3 "fixed" (but remotely moveable)electrodes, and 2
interconnected electrodes on the rotor. The rotor also has a central
electrode, and the connection that would normally go to one of the fixed
electrodes ( in a 2-gap solution, where there would then be 6 fixed
electrodes) is going to that central electrode, without a gap, but a
friction loaded contact.
Unfortunately this design, (which was suggested by Terry, when he made
his last rotary) cannot be altered in this coil, to make comparisons
btwn. 1 and 2 gaps, but the design here really was simplifyed a lot by
using this one gap solution, so I used it anyway.

I will work on this thing some more on separate gaps, where it will be
possible to reverse btwn both configurations, and see, if the loss added
in another gap is lower than the loss in the friction contact.

However, if each gap burns an equal amount of heat, then the losses
really should get smaller, since the friction contact barely is getting
warm.
(that is as ling as there really is physical contact. the other day
there was not, and the coil started to smell real bad real quick, as
mounting hardware around the contact started to get a-smokin)

Cheers, Finn Hammer

Tesla list wrote:
> 
> 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