RE: Triggered spark gaps for coils

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Gary.Lau-at-compaq-dot-com>

Hi Jim:

That's exactly what I was thinking, though not necessarilly at supersonic
speed.  I was going to modify my vortex gap (see
http://people.mediaone-dot-net/lau/tesla/vortexgap.htm)
by adding a small trigger electrode coaxially at the tip of one of the brass
reducer electrodes.  It seems that most commercial triggered gaps are sealed
and not rated for over 100 PPS.  I'm guessing that having moving airflow
will improve cooling (and quenching) allowing for greater PPS rates.

I'm also thinking that with the electrode configuration suggested by Bert
with the trigger electrode located and biased midway between the two main
electrodes, that the polarity of the trigger pulse needs to take into
account the polarity of the main electrodes, which in our case, alternates
between mains half-cycles.  This would make the trigger circuit more
complex.  Am I correct in thinking that with the configuration you describe,
the trigger polarity is unimportant, since it's the UV irradiation and
plasma that triggers the main gap into conduction?

Gary Lau
Waltham, MA USA


>Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>"
>>>><jimlux-at-earthlink-dot-net>
>
>A gentleman by the name of Marx (hmm.. high voltage? Marx? how odd?)...
>actually developed a series of air blast triggered gaps about a century
ago.
>An interesting design.. the electrodes are basically conical, and have
holes
>in the center through which the air flows (at supersonic rates, typically).
>Either you can pressurise the centers and blow radially out through the
gap,
>or you can pressurize the outside and blow radially in.  A center pin in
one
>of the electrodes (coaxial with the main electrode) provided the
triggering.
>Of course, back in the 19th century, they didn't have nifty HV pulse
>generators to generate the repetitive trigger pulses, so Marx used, of all
>things, a rotary spark gap to fire the trigger pulse.  The idea was that
the
>wear on the RSG would be much less because it switched a lot less power
than
>the main gap.
>
>By the way, getting supersonic flow in air is pretty easy.  100 psi through
>a 1/8" hole will easily get supersonic.  A regular old (pre-OSHA) blow gun
>will go supersonic as well.  If the weather is right, you can see nice Mach
>diamonds.
>
>> http://fp2.hughes-dot-net/brianb/pulse_discharge.htm
>>
>> Regards,
>> Brian B.
>>