Re: Capabilities of Small Thin Wire Secondaries (fwd)

---------- Forwarded message ----------
Date: Wed, 29 Jul 1998 10:49:20 EDT
From: FutureT-at-aol-dot-com
To: tesla-at-pupman-dot-com
Subject: Re: Capabilities of Small Thin Wire Secondaries (fwd)

In a message dated 98-07-28 23:14:53 EDT, you write:

> About those "racing sparks", what would be their cause? Where they
> appear? By your tests this phenomenon is associated with high couplings
>and some problem in the primary gap.
> May the problem be caused by excitation of higher-order resonance modes
> in the secondary coil? The fast envelopes of the secondary waveforms,
> or those peaks at the primary gap transitions may reasonably excite 
> transients at these other resonance modes, causing intense electric 
> fields along the secondary.
> Antonio Carlos M. de Queiroz


The sparks seemed to occur anywhere on the secondary, but 
probably more often in the middle third. I noticed in this and also 
in older tests, that the racing sparks are more likely to occur 
facing any metal protrusions on the primary, or if the primary comes
closer to the secondary at some point (due to sloppy construction--
the secondary is leaning, etc).  I have to place small sheets of
polyethylene over the primary tap point to prevent corona which
seems to promote the racing sparks.  The racing sparks definitely
seem to be promoted by field or corona stresses, and I think the
presence of the primary, and maybe the toroid, helps to promote
them.  It is also possible that as the toroid sparks dance around,
this may cause locallized stresses on the secondary also, and
promote the racing sparks.  In a few cases, the racing sparks
travelled the full length of the secondary and turned into a full
toroid to primary arc.

I've noted in these and other tests that larger toploads make the
racing spark problem worse.  The racing sparks may just be a
precursor to overall (end to end) secondary breakdown in some
cases.  In other cases high coupling and poor quenching are
the cause.  As you say, there are possibly other mechanisms
at work. 

John Freau