Re: 20 joules at 100 bps vs 4 joules at 500 bps - any difference?

["Tesla list" <tesla@xxxxxxxxxx>]

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

Since this one of my pet coiling interests I'll comment:

On 13 Jul 2005, at 12:26, Tesla list wrote:

> Original poster: "father dest" <dest@xxxxxxxxxxx>
>
> hi Terrell, John.
>
> so, what does the spark`s length influenced by - power or bang size?
> you both are saying that bang size does, but look here:
>
> <http://members.aol.com/futuret/page5.html>http://members.aol.com/futu
> ret/page5.html
>
> "In a well designed TC, the spark length will follow the formula:
> spark length (inches) = 1.7*sqrt input power (wallplug watts)"
>
> there`s no connection with single discharge energy here, but i know,
> this equation works and works well - that`s why i`ve asked my
> questions.
>
> John - how would you comment your own  equation? in this way:
>
> "Any coil that gives a certain spark length at a high bps, can be
> redesigned to give an even longer spark for the same power input at a
> lower bps" ?

The hidden implication in that comment is that the higher BPS coil is
not matching the maximum sparklength formula. Bang size is all-
important. It is a major determinant of output voltage for one thing
(assuming a suitable ROC for the topload). It also maximizes energy
dumping into a growing leader (highly ionized, not just residual hot
air) i.e. successive bangs are discharging into a hot air channel but
energy during the bang is feeding ionized air once ionization is
initiated. To get the best out of a coil (and possibly beat the
formula ;) the basic recipe is:

- make the secondary tall/long enough that it will not flashover with
the maximum Ep that will be thrown at it
- make the topload ROC such that the coil will barely breakout with
the maximum voltage it will develop with a maximum bang size
- for a given power supply capability, optimize the system such that
available power = BPS x Ep such that BPS is lowered to around 100Hz
(mileage will vary a little) and Ep is maximized to compensate.

     The reason for giving 100Hz-odd as the minimum breakrate has to
do with the air cooling too much between bangs thereby reducing the
bang-bang streamer growth phenomenon. Bearing in mind that most
coilers are chasing massive sparks rather than global energy
transmission the ionization characteristics of air are a major
consideration.

Malcolm

> but it`s not similar to Terrell`s words:
>
>  >the 20 Joule system should have arcs SQRT(20/4) = 2.236 times
>  longer.
>
> _too_ large difference.
>
> p.s.
> i`m disturbed by the following: at 100 bps i have too heavy currents
> in the primary circuit - 1200 a peak and approximately 10 a rms -
> there would be some problems with a capacitor & large loses in the
> wires. and it`s only 2 kW!!! what can happen at 5 kW or 10 kW at 100
> bps - terrible %-)
>
> ---
>
> Your not coiling unless your blowing capacitors! Then when you get
> things worked out to where the capacitors stop blowing, you start
> blowing transformers. (c) Richard Quick 11-03-93 20:42
>
>
>