Re: Does it matter which way i wind my secondary?

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bert.hickman-at-aquila-dot-net>

<SNIP>
> > In a typical system powered in AC, the two coils will show exactly
> > the same performance.
> > If the system is powered in DC (the primary capacitor is charged always
> > with the same polarity), I would expect some slight difference in the
> > spark output, because it's easier to have breakout with negative
> > voltages than with positive voltages.
> 
>         Are you referring to the polarity of the first peak of the secondary
> voltage of a heavily-coupled coil?
> 
> > Antonio Carlos M. de Queiroz
> 
> Ed

Antonio, Ed,

Actually, per B&R it's apparently the other way around. For the
divergent field case, breakout is actually easier when the HV electrode
is the anode not the cathode. When the HV electrode is the anode, free
electrons find themselves in an increasing electric field as they
approach the anode (or leader tip coming from the anode), further
promoting ionization avalanching. When the HV electrode is the cathode,
electrons find a decreasing electric field as they travel further away
from the cathode (or leader head), decreasing their effectiveness in the
ionization avalanche process. In effect, a negative leader finds it
"tougher" to propagate than a positive leader. As a result, gap
breakdown becomes more difficult with a negative HV electrode versus a
positive one, requiring a higher voltage when the HV terminal is the
cathode. For VERY long sparks (~100+ meters), this difference
disappears. 

However, I seem to remember some empirical evidence that this was not
necessarily the case during some TC breakout voltage measurements. And,
I also seem to remember that the current measurements taken on Electrum
DID seem to support positive polarity as being preferred, but I'll have
to check back into the archives...

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com