Re: [TCML] Re:Pros and cons

[Steve Ward <steve.ward@xxxxxxxxx>]

Dex,

Perhaps this is because a single VTTC spark event is equivalent to a series
of burst spark events at extremely high pulse rate and duty cycle.  Just as
we suspect that the effect on spark growth vs burst rate reaches an ultimate
limit, i think the pulse of a VTTC may very well define that limit.

I do know that with my SSTCs running long spark times (in the mS regime) the
spark does not grow much at all (in length) after about 1-2mS, the next
5-6mS just make it appear "thicker" or "bushier" but not longer.

Thoughts?

I also did try running high pulse rates at low bang energy with my DRSSTC.
I need to expand on my pulse rate capability (currently limited to 500pps)
to see if even lower energies will grow long sparks at these rates.
Eventually the line between a sequence of short pulses, or a CW coil thats
interrupted, becomes blurred.

Steve

On Wed, Dec 16, 2009 at 1:24 PM, Dex Dexter <dexterlabs@xxxxxxxxxxx> wrote:

> Yes,but please explain me why VTTC sparks don't successively
> extend in multiple pulses regime through a previously
> ionized channel?Ionization of the previous channel is not
> high enough or?I would say an average temperature of VTTC
> channel is even higher than that of SGTC spark.
>
> Dex
>
>
> --- jimlux@xxxxxxxxxxxxx wrote:
>
> From: jimlux <jimlux@xxxxxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Subject: Re: [TCML] Re:Pros and cons
> Date: Tue, 15 Dec 2009 20:01:42 -0800
>
> Steve Ward wrote:
> > Hi Dex,
> >
> > Glad you could chip in here a bit, i was having trouble finding any good
> > references for coils with discharges much longer than the top voltage
> would
> > suggest.  More comments
>
> I suspect that most coils are in this category. at 30kV/cm, 200-300kV
> (which is probably a typical topload voltage for a small NST coil) would
> only support a spark of 7-10cm, and sparks much longer than that are
> common.
>
> The difficulty is multifold:
>
> The field is very non-uniform, which tends to lead to longer sparks,
> even in a single shot environment (Bazelyan and Raizer's book talks
> about this a lot, in connection with EHV and UHV transmission systems
> and switchgear)
>
> you have multiple pulses which can successively extend the spark through
> a previously ionized channel.
>
> As an obvious indication of unusual behavior, a lot of coils have sparks
> longer than the distance from topload to base, without arcing over the
> secondary coilform.
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