Re: How should we measure coil efficiency, was neon vs. pot

From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Wednesday, July 23, 1997 3:07 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: How should we measure coil efficiency, was neon vs. pot

To help clarify....

> From:   FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
> Sent:   Tuesday, July 22, 1997 3:15 AM
> To:     tesla-at-pupman-dot-com
> Subject:    Re: How should we measure coil efficiency, was neon vs. potential transformer
> >snip>
> ><< However, comparing performance (Length/watt) between optimally sized
> > coils may have significant merit. For every power level, there will be
> > at least one coil in the population of all coils that has the greatest
> > streamer length/watt. These would represent the most efficient coils in
> > their power class by our sparklength/watt measurement criteria - the
> > "state of the art" in coildom. However, for this to work, a consistent
> > way of measuring input power and output sparklength is needed. The
> > electronic opto-electronic wattmeter or simple 60 Hz analog wattmeters
> > may suffice as long as we were consistent. Streamer length may require a
> > more rigorous definition, like "attached streamer" not just one single
> > "strike". The proposed square-law relating length to power level is not
> > unreasonable... more coil data should provide more data points...
> > Safe coilin' to you!
> > -- Bert --
>   >>
> Bert,
> I'm thinking now (thanks to Greg's and Malcolm's suggestion), that we 
> should add the figure for capacitor energy, and measure our coils in two
> steps; wallplug to capacitor...and capacitor to spark length...this way we
> know which sections of our coils are efficient and whether the two types 
> (areas) of efficiency will co-exist or "rebel".  (I'm a little leery of high
> break
> rates...concerned it will hurt efficiency in one way or another?)
> My fear with the attached streamer measurement method is that it may
> give an inaccurate correspondance to the free air, or occasional hit length.
> If I understand Malcolm's recent experiment, the break rate altered the
> ratio of attached vs. free-air streamer length.

It did indeed. I got attached hot streamers at 6" with a lower Vp and 
higher break rate than running at highest Vp and fewer BPS. The 
streamers coalesce into fewer but hotter free air streamers as 
break rate increased to the point where the concentrated power 
was able to connect the terminals in hot single-channel sparks, even 
at the expense of primary voltage. The shower of thin, long-reaching 
free air streamers (rather faint, even in the dark) shortened as Vp 
decreased but concentrated into a few hot ones. These effects are 
much more dramatic at higher power levels. In the low power 
experiments, the thin wispy streamers connected the terminals out to 
8" or so but you could hardly see them and there was a ghostly band of 
these rather than a single hot channel. This was with a measured 
primary power of 33W from memory.

     In my 1.6kW system (with terrible transformer losses), bright 
single channel sparks attach to surrounding objects at 52" (measured)
at 100 BPS but connect to objects at a mere 11" at 1 BPS with the 
same gap setting. I have just gone and checked this. The faintest St 
Elmo's fire I could detect from the sharp point of a grounded rod
was at a distance of 32". The greatest distance I could get a band
of wispy streamers to connect with my hand was about 16". I wouldn't 
get within six feet of it at 100 BPS. Ec is 2.8J (measured). Estimated
Vout (ignoring losses) and by conservation of energy is 460kV. Cp is 
0.1uF and Cs(tot) is 26.3pF. It would be most interesting to see what 
would happen at, say, 300 BPS with the same gap setting. I have to 
figure out a way to do this - the transformer has far too much 
resistance in its windings. Time for a new type of supply so I can 
keep the gap setting constant perhaps.

Much work yet to be done,