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Re: Output Voltage vs. Firing Rate (fwd)



---------- Forwarded message ----------
Date: Wed, 5 Aug 1998 18:12:54 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Output Voltage vs. Firing Rate (fwd)

Hi Terry,

> Date: Mon, 3 Aug 1998 21:46:29 -0600
> From: terryf-at-verinet-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Output Voltage vs. Firing Rate
> 
> Hi All,
>     We were having a little Colorado Tesla meeting on Sunday.  I noticed that
> my gap seemed to give better sparks when the gap was set to a lower voltage
> than maximum.  In other words, The streamers were longer with lower gap
> voltage settings.  Modeling shows that this is probably due to the fact that
> the firing rate probably increased by a factor of three from 120 Hz to 360 Hz.
>     I have always tried to design coils to create a very high output voltage.
> However, Sunday's experiments would suggest that we need a higher firing
> rate ( >120 Hz ) also.  In fact, one may need to sacrifice substantial
> output voltage to increase the firing rate to get the best streamers.  My
> latest gap design will be able to explore this realm in far greater detail.
> I suspect that once the output voltage is high enough to cause breakout, we
> need to use firing rate the push the streamers out rather than pure voltage.
> High voltages tend to cause many short streamers while high firing rates at
> lower voltage tend to create a single but much longer streamer.  Obviously,
> this subject is very important to our endeavors.  

I think it fundamentally boils down to power and the best mix of 
average current and voltage. I have had good results at just 100BPS 
with a moderately large coil. It is the only one that has performed 
satisfactorily at such break rates. The smaller coils do not do as 
well.

>     My next gap design will allow easily adjustable voltage, high power, and
> very good quenching that should allow for very optimal adjustments of these
> parameters that seem important.  If anyone has any input to such issues
> please let me know.  

I'll be doing some expts with my new adjustable gap and the storage 
scope this weekend. I'll report if I find anything new. I'm going to 
have a serious crack at finding the Corum's coherence (change in V/I 
distribution in the resonator), probably with no topload to minimize 
the lumped element.

>     I was very impressed with Dave Burman's vacuum gap.  I never have used much
> airflow before but there seems to be a substantial advantage to having a lot
> of high-speed air flowing through the gaps.   Not only does air improve
> quenching but it also aids cooling.  With a little larger pipe and much more
> airflow, my present gap design can be greatly improved.  Hopefully, a static
> gap could handle very high power levels and still give excellent quenching.
> I suspect that the firing voltage can be carefully adjusted to give the best
> output potential and firing rate in order to produce the longest streamers.
> There is probably a "sweet spot" between these two factors.

Agree although I would expect the sweet spot is different for 
different setups. 
    Just while I'm thinking about it, has anybody on the list managed 
to make ball lightning with their coil using either one of 
the Corum's methods? I'm going to have a serious look at that as well 
in the coming week.

Regards, Malcolm