Re: Spark Dissipation

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

>  
>  Hi Gary, all,
>  
>  I also see no signs of spark "growth" using successive RF bursts in my
>  SSTC system.
>  The one shot spark length is as long as the length when firing in high
>  speed repetition.
>  
>  I had mentioned this to John Freau,  and he said that this darting
>  un-coalesced spark
>  behaviour is the norm with pulsed Vaccuum tube coils too.
>  
>  It seems odd to me,  that even with repetition rates as high as 500BPS
>  or so, successive
>  sparks from an SSTC refuse to follow in the paths of previous spark
>  channels.

Hi Richie, Gary, all,

Yes, it is strange.  When I get the staccato swordlike sparks, I think
the streamers do follow the same path, but they still don't grow longer much.
Stranger yet, the swordlike sparks remain the same length at any rep rate,
but the branched sparks seem longer at faster staccato rates, more like
a disruptive coil behaviour.  I guess my branched staccato sparks were
about 30" long at 20PPS, but only 24" long at 5PPS.  


>  This seems even more strange when you consider that conventional spark
>  gap coils produce
>  slowly drifting sparks which clearly evolve through repeated ionisation
>  of existing channels,
>  using repetition rates as low as 100BPS !

>  There is definately something strange going on here.  I would bet that
>  it has something
>  to do with the different ring-up rates in Solid State and conventional
>  coils,  that you
>  touched upon in your previous post.  The bust energy in a conventional
>  coil would certainly
>  seem to be expended over a shorter period of time.

Yes, and it's all a ringdown waveform as opposed to steady or rising
envelopes in a tube coil.  Maybe the branching is a factor too?  Maybe
branched sparks actually grow better than straight knife-like ones?

In an intuitive sense, I picture the very thick heavy discharge from a tube
or SSTC as *capturing* the sparks within themselves, and not letting
the ends grow.  Maybe a factor of the low Z of these sparks too?  Thick
low Z sparks may be unable to grow?
>  
>  I'm a newbie to this SSTC thing,  (and know nothing about VTTCs,)  so I
>  would be very
>  interested to hear if others have obseverd similar behaviour.
>  
>  For some reason,  it would seem that the thin streamer-like sparks from
>  a conventional coil
>  are in some way more susceptable to being re-ionised than the much
>  fatter sword-like sparks
>  from a SSTC or VTTC.

It may have something to do with the ends of the streamer where growth
occurs.  My branched (thinner?) VTTC sparks seemed to be more able
to grow than the unbranched (thicker?) swordlike sparks.  Or maybe
the branched sparks creates a cloud of ionization that persists better
(or works better) because it is spread out more?

Cheers,
John

>  
>  An explanation,  Anyone ???
>  
>                                                                         
>  Cheers,
>  
>                                                               -Richie,
>