Re: 20 joules at 100 bps vs 4 joules at 500 bps

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hello Dmitry,

On 1 Aug 2005, at 11:16, Tesla list wrote:

> Original poster: "Dmitry (father dest)" <dest@xxxxxxxxxxx>
>
> Hello Malcolm.
>
> Tl> Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>
> Tl>  > Original poster: "Dmitry (father dest)" <dest@xxxxxxxxxxx>
>
> Tl>  > "high voltage helps to induce leaders from target objects" -
> how - by Tl>  > mean of electrical induction? but following Kulon`s
> law the force, Tl>  > acting at remote charge depends only from the
> toroid charge and Tl>  > distance to the target. toroid charge could
> be made the same at any Tl>  > secondary voltage - we only have to
> change toroid capacitance (primary Tl>  > voltage, e.t.c.) actually we
> can`t consider toroid as a point charge Tl>  > :-) but the field
> strength around the toroid  depends greater from its Tl>  > ROC than
> from the secondary voltage.
>
> Tl> If I understand correctly what you've said above, you would
> consider that Tl> a large capacitance (e.g. conductive toroid) charged
> to a low voltage Tl> would induce leaders from an object at some given
> distance to the Tl> same degree as a low capacitance charged to a high
> voltage (same Q in Tl> both cases)?
>
> yes, it`s exactly the same as i wanted to say/ask - sorry for my
> stupid english - Kulon`s law = Coulomb's law :-)

I'm sure I'm not the only person who's been trying to figure out who
"Kulon" is or was!

> Tl>  I can't say I've observed that but then I can't rule it
> Tl> out either not having done a definitive expt. It kind of goes
> against Tl> "commonsense" but then commonsense has not proved to be
> reliable in Tl> many areas either.
>
> it`s just a question, i`ve not built any coil in my life - so this
> statement could be an absolute nonsense :-) let`s think logically - to
> make a leader from the target it must have a big charge at small
> square - right?

I assume you mean big charge over small area? If so, then small area
= small capacitance and voltage = high.

> to induce this charge we have to act with a big force
> at free charges in the target - right? the force according to
> Coulomb`s law is proportional to toroid charge. field strength,
> generated with a toroid on a large distance is proportional to the
> tor`s charge too. what`s not right in such statement?

Here I admit to having trouble understanding exactly what you are
saying. It would be pointless for me to comment further if my 	
understanding is incomplete and just a waste of bandwidth. This is a
reflection on myself, not you.

> Tl>  > b.t.w. - how i must take into
> Tl>  > account flashover voltage? imagine i`m building 4" coil,
> secondary Tl>  > height 20", frequency at around 220khz - how could i
> know that Tl>  > voltage? or - i`ve calculated the toroid voltage (70
> cm diameter) - Tl>  > 1.2 MV - what height should be the secondary to
> prevent flashovers?
>
> Tl> There's a bit of suck and see.
>
> oh no no no - i`ve no time, so i prefer to "read & see" :-)

Learning is by doing so I've found.

> Tl>  Mileage varies depending on
> Tl> atmospheric conditions. Surface tracking also plays a part. I
> think Tl> Greg Leyh's Electrum coil may have shown a tendency to
> flashover at Tl> odd times and has an output approaching 1.5MV.
>
> let`s see:
> http://www.lod.org/Projects/electrum/techdata/electrumspecs.html
>
> "SECONDARY COIL TOWER STRUCTURE
> Lsec = 0.130H
> Fsec = 37.92kHz (w/7' spherical electrode), 52.60kHz (no electrode)
> Isec (pk) = 61A, with full primary voltage at 38kHz Total tower height
> - 38' 8"
>
> 61 a means that bang energy = 241.86 joules - real "big bang", i love
> this guy %-) total capacitance of discharger and the coil would be 135
> pf, then secondary voltage is 1.9 MV. and 38' is not enough for such
> voltage?

I did not mean to imply that it is not enough. It clearly is most if
not all of the time. I have seen at least one photo of an arc
reaching down from the top and striking it part way down. I don't
recall seeing one of surface tracking but I do seem to remember
hearing that it has been observed to do so. Maybe not. Point is, how
much shorter can you make it before it does become a problem at 1.9MV
(I assume that figure is calculated as though the coil had no
losses)?

i don`t believe - maybe some construction feature are
> involved, maybe lack of thick coats of poly ^___^ and it seems that
> sphere protects the secondary worse than toroid:
> http://www.lod.org/Projects/electrum/testing/pages/electrumeric.html

That last statement is true where the sphere diameter is less than
the major diameter of a toroid and may be true for even larger sphere
diameters since the widest part of the sphere is elevated by the
sphere's radius above the top of the coil. Of course the same applies
for a toroid which is mounted some distance above the top of the
coil.

> Tl> Flashover distances do not appear to follow a linear V/d curve.
> Tl> Charge availability might well play a part - that's something Tl>
> I've never looked at :(  Another coiler (Robert Stephens) killed a Tl>
> tendency for one of his coils to flashover by placing a series of Tl>
> acrylic disks along the length of his secondary to increase the Tl>
> creepage distance, fluted insulator-style.
>
> it`s widely used in power engineeringc, really - why not glue these
> discs with a poly? the coil would look like a giant insulator :-))) i
> must try this in the future - maybe then up to 6 secondary heights
> would be shooted? :-)

Maybe - try it and let us know.

> Tl> I also observe that a secondary that is run just under its
> Tl> flashover voltage in single shot operation is almost certain to
> Tl> flashover in repetitive running at the same voltage.
>
> but it`s the same as increasing streamer length by composition of
> several bangs - residual ionization.

Yes.

> Tl> If you can quantify these things for me I'd be delighted.
>
> no, not me, at least not before you :-)

So when are you going to build a coil and contribute to the pool of
knowledge?

Malcolm