Re: Final test on new TC

            Re: Final test on new TC
            Thu, 03 Apr 1997 08:38:26 -0800
            Skip Greiner <sgreiner-at-wwnet-dot-com>
            Greiner, Ltd.
            Tesla List <tesla-at-pupman-dot-com>

Tesla List wrote:
> Subject:
>         Re: Final test on new TC
>   Date:
>         Tue, 1 Apr 1997 13:24:07 -0700
>   From:
>         "DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
>     To:
>         "Tesla List" <tesla-at-pupman-dot-com>
> To Malcolm Watts:
> Another test relating to quench you might try is as follows:
> Set a ground electrode (point) at a fixed distance from your sec. coil
> and
> also have a point on the sec. coil.  Turn your variac up to normal
> operation point and -- with cold sparkgap electrodes -- hit the start
> button.  If your spark jumps out to (for example) around 50 in. and then
> suddenly shrinks within about 5 seconds down to 40 in. this is
> indicating
> your sparkgap electrodes are overheating and quenching inadequately.  If
> your quench is proper and electrode size is large enough your spark will
> stay at 50 in. (or whatever length max. is) and will not "shrink" down
> in
> size.  We noted this effect by testing various size electrodes and
> noticed
> it is especially pronounced with small 1/8 inch dia. electrodes either
> on
> sub-divided stationary gaps and rotary gaps.  We eliminated this shrink
> effect by using 1/2 in. dia. electrodes in a suitably large brass
> heatsink.
>  No shrinkage of spark discharge from sec. terminal.
> Just thought I might mention this effect to keep in mind as you continue
> your quench and coupling experiments.
>         DR.RESONANCE-at-next-wave-dot-net
> Hi Dr. Resonance and All

This is extremely interesting. I have noticed the same phenomena occur
when the variac voltage is reduced temporarily and then increased
rapidly to maximum. The spark increases to some maximum and then recedes
to a shorter length. I had been unable to explain the problem. I use
0.25" rotating contacts which are relatively long so they cool quite
quickly when the power is reduced. I used small diameter contacts
because I erroneously thought that the dwell time was being controlled
by the contact diameter. Apparently bigger is better in this instance.
Thank You.