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Gaps and tank Q
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From: Greg Leyh [SMTP:lod-at-pacbell-dot-net]
Sent: Saturday, March 07, 1998 5:48 AM
To: Tesla List
Subject: Re: Gaps and tank Q
FutureT wrote:
> Has anyone determined how much the gap losses are likely to increase
> when using 8 to 12 multiple series gaps, either static or rotary,
> compared to a smaller number such as two?
>
> Probably a high surge impedance primary is more tolerant of multiple
> gaps, since the the gap losses tend to be a smaller percentage of
> total tank losses in the high surge impedance primary case. Has
> anyone looked at this?
On the coil I'm working on at present, the number
of gaps in series doesn't seem to make a measurable
difference to tank losses!
Normally I perform the coil tuning in the single-shot
mode (~1BPS) using 250W 50kV cap charger power supply
and an adjustable static gap, made out of two pieces
of 2" Cu tubing. I monitor the peak _secondary_ base
current with a wide-band CT, and seek to maximize it
by setting the tuning taps. With this static gap,
the secondary generates ~60A pk, with a Vpri of 44kV.
Then I removed the static gap and positioned the
rotary gap armature so that all 8 series gaps would
breakdown at 44kV, just like the static gap.
Guess what Isec pk I got? ~60A pk! The two msmts
were certainly within the msmt noise (and gap firing
uncertainity) of each other! Why are they the same?
Maybe we should ask "Why should they be different?"
Given that the gap losses are similiar, I believe that
the multiple series gaps still have the advantage of
enhanced quenching action, due to the lower voltage
(and therefore lower energy ion bombardment) upon
each electrode.
BTW my primary surge impedance is about 15.5 ohms.
-GL