Re: IGBT SSTC finally possible?

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

Original poster: FutureT-at-aol-dot-com 

In a message dated 4/24/04 7:29:19 PM Eastern Daylight Time, 
tesla-at-pupman-dot-com writes:

>Yep. my new coil completely resembles a medium sized SGTC except one
>difference.  The sparks seem to have more energy and thickness.  When they
>strike something they stick to it, and ground strikes are very cool.  But
>basically they look JUST like a normal SGTC.



Steve,

So you're saying the sparks look just like the sparks of a normal SGTC?
(except they have more energy and thickness).  That is a major
advancement.  The OLTC of course also produces normal SG type
sparks, but it uses cap discharge and ringdown.

I think Ken H said he needed to run his durations at about 350uS
before breakout because he used a large toroid.  So maybe if you
had such a large toroid, you'd need similar durations to break out?

It seems to me that if the primary is resonantly building up energy
in your coil design, then this energy would also be transfering to the
secondary at the same time.  So the coil may follow CW type
energy transfer rules rather than disruptive coil rules, for the primary
to secondary energy transfer,even though your coil is pulsed.
Of course this depends on how one defines *CW*.   In any
case the energy builds.  By using a filtered DC
supply, this gives the storehouse of energy that is needed for
large peak voltages and currents.  This is something like my
pulsed DC tube coil work that used filter caps to store large
amounts of peak energy despite a low peak energy draw from the
mains.  The difference was that my system still had the very
long 8mS duration.

What sort of coupling do you use?  Does the system require a
tight coupling?


>Is that the case?
> >What type of pulse-rates and durations are you using, and how
> >is the pulsing controlled?
>
>For my coil, the pulse duration is about 150uS at anywhere from 30 to 300bps.
>
>Have you compared various pulse-rates,
> >and firing pulse durations, etc.
>
>Yes, and basically, longer pulses give longer sparks until a point where
>they dont get longer, but thicker.



It's possible that SGTC's do the same thing at high break rates.
This may be just a characteristic of high break rates, based on
the nature of spark-growth in air.

     The problem is, the voltage and current

>build up with my coil, so the longer its on, the higher the peak currents
>and voltages reach (my setup will hit 600A peak and about 9kv in the tank
>circuit even though im supplying only 350VDC... sorta like resonant charging).



No wonder you're getting long sparks !   Who needs NST's right?  LOL.

I think the relatively short duration pulses also contribute to the
spark appearance.  It seems that long durations tend to produce
more flamelike, thick sparks.

Well it's all very interesting.  I hope to find time soon to work on
such things.

John