TSSP: List Archives

From: boris petkovic
Date: Fri, 4 May 2001 12:42:32 -0700 (PDT)
Subject: Re: [TSSP] Time domain modeling



> For example, I've always assumed that breakdown of
> the sec
> is likely if k is taken too high, due to the induced
> EMF
> from the primary exceeding the turn-turn breakdown
> of the
> secondary.
---
This should be one of the reasons.
But there's more .
Do not find yourself surprised when TSSP time domain
simulator start show you high distortion of voltage
profile curve during voltage buildup for k>>. 
---
> 
> Havn't got a full picture yet, but other
> possibilities
> arise. The familiar pri-sec beat is the sum of two 
> normal modes, more or less equally excited by the
> initial
> bang. For small k, the modes are close and very
> similar
> sec I distribution I(x) for each, but of opposite
> sign, relative
> to Ipri. So with equal amounts of each, the two sec
> I(x) cancel
> out to around zero, and the two Ipri add up to the
> amount
> required for the bang. As k increases the modes move
> apart and
> also change shape. Cancellation is now no longer
> perfect, and 
> thus higher modes need to go into the pot in order
> to recover
> the match to the initial conditions. Energy in the
> higher
> modes has a roughly proportionally higher voltage
> gradient
> on the secondary, eg 3/4 wave has almost 3 times the
> volts
> per metre than 1/4 wave, for the same terminal
> voltage. Hopefully
> we'll be able to tell if this mechanism contributes
> to 
> difficulties of using high k. We'll also soon be
> able to see
> if the conical primary makes life easier in this
> respect - we
> might expect its 'smoother' application of EMF to
> couple
> less to the higher modes. Sorry for the handwaving,
> just a
> few thoughts. The math and computations should spell
> this out
> more rigorously.

---
We'll see ...
--
> 
> I wrote:
> > > >The reason I ask is that, depending on just how
> > > long the arc
> > > >discharge path can be considered to be
> grounding
> > > the top of the
> > > >coil, it looks like quite a substantial amount
> of
> > > energy can be
> > > >transfered into one of the higher modes, to be
> > > trapped there.
> 
> Boris wrote:
> > Correct.The freq. of power discharge depends on a
> > isotropic C, physical size of isotropic
> capacity(not
> > just on C but there is difference wether toroid
> > /sphere etc.used),density of coil turns and I
> suspect
> > to some extent on geometry of outter path to
> ground
> > coil discharges into.
> 
> Yes, but I'm not too concerned with the high
> frequency 
> components of the arc itself - I wouldn't know where
> to
> start to calculate these. Just that, while the arc
> is
> present, the solenoid is effectively grounded at
> both
> ends, with an appropriate set of modes for this
> boundary
> condition, and the longer this condition persists, I
> think
> the greater is the energy is transfered from the two
> main
> modes into higher order resonances
snip>

In single pulse mode,if more than 80% of possible arc
gap lenght being allowed,you may take that power arc
discharge starts in the moment near the point of peak
voltage set on the resonator (usually,a few couples of
el.degres after waveform passes peak voltage).
The transient dissipates most of the trapped energy of
the system in time interval shorter than microsecond.
However,the freq. of discharge isn't so high one could
judge by the geometry of outter circuit but somewhat
lower due to the coil presence  itself.

In repetitive pulse mode,80% limit drops down bellow
50% of possible arc gap lenght allowed and same story
still holds.
Picture altogather is very verycomplicated,especially
for repetitive operation since the caotical properties
of arcs more expressed.

The things I said are supported by data taken on 3
repetitive operated systems ,and 1 single pulse
operated.
If we must ,let we stick just to arcs shooting in air.


Regards,
Boris   
  


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