[TCML] Re: Slo-Mo Videos of Tesla Coil

[Greg Leyh <lod@xxxxxxxxxxx>]

Bert wrote:

>> (Greg Leyh wrote:)
>>

> > Hi Bert,
> > > 
> > > Interesting, that recovery time is fairly independent of prior arc 
> > > current or gap spacing.  It makes sense that increasing topload capacity 
> > > and peak output voltage are important towards obtaining maximum spark 
> > > length.  So, given a fixed energy per bang available to the secondary, 
> > > how might you imagine trading off voltage and topload C?   GL
> > > 
>
> Hi Greg,
>
> I'm not sure there is a clear answer to this question. My 2 cents worth 
> for large coils...
>
> Let's assume that your topload is sized so that that it provides 
> sufficient electrostatic shielding for your secondary, the minor ROC is 
> large enough to prevent initial breakout for the highest expected 
> secondary voltage, and the topload has an adjustable breakout 
> bump/projecting rod to tweak initial breakout voltage and direction.
>
> One could argue that a topload that satisfies the above criteria may 
> provide the optimal trade off between topload C and output voltage for a 
> large system. The "larger toroid is better" strategy that worked so well 
> for smaller systems may reach a point of diminishing returns on large 
> systems. Since large systems already use physically large toploads to 
> satisfy shielding requirements, the resulting topload C already provides 
> a sufficient reservoir of charge to support efficient leader/streamer 
> propagation. Further oversizing the topload lowers peak voltage but may 
> not significantly improve spark growth processes. Spark propagation will 
> cease when the field at streamer tips drops below about 5 kV/cm. Spark 
> length is (ultimately) constrained by maximum terminal voltage. The 
> objective should be to maximize V (commensurate with a topload sized to 
> meet shielding and breakout restrictions).
>
> Your thoughts?
>
> Bert

Guess I'm wondering why the "larger toroid is better" strategy worked 
for smaller systems in the first place?  Does there need to be some 
minimum, low inductance, reservoir of charge supporting the base of the 
arc?   GL

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