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Re: Conditions for opt. loading, was: In vs. Out


From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Wednesday, July 30, 1997 10:27 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Conditions for opt. loading, was: In vs. Out

Hi John,

> From:   FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
> Sent:   Wednesday, July 30, 1997 3:10 AM
> To:     tesla-at-pupman-dot-com
> Subject:    Re: Conditions for opt. loading, was: In vs. Out
> 
> In a message dated 97-07-30 07:19:38 EDT, you write:
> 
> << 
>  >> > I like this idea, but how will we obtain optimal loading?  Still it
> could
>  >> > give us useful information.
>  > >  
> >> Two ways: minimum gap brightness and/or first notch quench (for those 
>  >> that have scopes).
>  
> >You asked how. The above is the visual indication. How to do it:
> > Attached sparks at maximum stretch for attachment (for the ionization 
> > level present) gives this condition. This corresponds to maximum V x 
> > I product in the secondary output summed over ring time for a shot
> > using the above indicators. Output to air streamers appears to be 
> > capacitively loading while attachment is mostly resistive (at Fr).
> 
> Malcolm,
> 
> I was under the impression that attached sparks degraded the 
> quenching because of the impedance mismatch and resulting reflections.
> Are you saying that certain lengths of attached sparks, or perhaps
> non-hard grounded attached sparks give the proper loading.  I'm not
> too clear on all this it would seem.  I'd appreciate it if you could spell
> out the conditions for proper loading.  Do these attached sparks have to
> be the permanently attached (short) types?      Thanks.

I've found that it is critical to hit the "right" spark impedance for 
optimal loading to occur. This occurs (at least at modest k values) 
with an attached streamer that is the longest it can get before 
detaching. Using shorter attached sparks than the coil can produce 
does produce a mismatch. If you move a ground rod up to a running 
coil, the optimal length is easy to see in a dimmer gap discharge. 
Moving the rod closer than this brightens the gap up again.
     I could write a book on it. Perhaps the best way is to try it 
single shot, then try it for the running coil. The lengths are 
different as you have energy stored in the discharge channel/ion 
cloud for the repetitive situation and I've found under this 
condition, optimal loading occurs with longer sparks than sshot.
    It is kind of difficult to elaborate further without giving an 
actual demonstration (which I would dearly love to be able to do).

Malcolm