Re: Racing sparks, streamer growth, coupling, etc.

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-uswest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
 
> Original poster: "Malcolm Watts by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

> dV/dt can be significantly higher with increased coupling but
> obviously depends on the degree of coupling. 

Just 8% greater at k=0.6, in a lossless system. See my other post
(that I didn't see back yet).

> It is in fact the
> changing slope of the secondary ring which gives rise to the
> sidebands as viewed in the frequency domain and these move further
> apart as k increases. 

The "beats" are shorter, with less cycles.

> dV/dt increases with k on both a per cycle
> basis and on an average (rectified if you like) basis. 

Yes, but the maximum value is limited, and (for reasonable values
of k, <0.6), independent of k.

> Note to all
> those non-believers out there - the sidebands are present if you view
> the secondary e-field only - waveforms looking like a ringup/ringdown
> generated by whatever means can be mathematically shown to have
> dual/multiple frequency content. 

cos(a)*cos(b) = 0.5*(cos(a-b)+cos(a+b))

> Although a tuned primary is part and
> parcel of a TC it is not a precondition on producing what is
> essentially a DSBSC envelope.

Really. Happens also on mistuned coils, or in anything with two
capacitors and two coils with nontrivial connections.

>      But output voltage can also reach a higher value with the same
> Ep and increased k as the primary gap is given less time to lose it.

The reason for use of k=0.6 (energy transfer in 1 cycle) in pulsed
power devices for research.
 
> It stands to reason that if the secondary attains some voltage more
> quickly, dV/dt must have increased. Scope observations suggest that
> the secondary pretty well rings up before a spark lets go in most
> systems whether it is the initial discharge or part of a repetitive
> train.

What increases markedly is the difference between succesive peaks
of the secondary voltage. The actual maximum dv/dt of the secondary
voltage, at the last zero crossing before the complete energy transfer 
(of before this if breakout occurs earlier) is almost independent 
of k.

Antonio Carlos M. de Queiroz