Re: Best sparks (fwd)
---------- Forwarded message ----------
Date: Sun, 5 Jul 1998 18:23:45 -0600
From: "D.C. Cox" <DR.RESONANCE-at-next-wave-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Best sparks
to: Terry, Richard, Tesla List
Terry listed an equation regarding the spectral emission from the arc
itself. This equation listed the RC time constant as a source for the
generated frequency. This is incorrect. RC time constant is a dissipative
factor. It will not store energy like an LC time constant value and does
not support resonance, in fact, tends to reduce or oppose any resonant
buildup. These three frequencies all listed by Terry are in fact generated
after the arc discharge travels off the high voltage terminal. In is not
associated with the capacitance of the sec coil or its inductance.
Standing waves and transmission line effects are produced in the spark
discharge itself and the generated frequencies are not associated with the
fundamental frequencies of the secondary inductor. These frequencies are
dependent on the geometry and LC constants of the arc channel
As Rich Hull points out, lightning is an example of a rich source of RF
frequencies, however, these frequencies tend to be much lower than
originally suspected. The Russian scientist, Kapitza, had a theory that a
considerable amount of UHF power was being generated to produce plasma
fireballs, and hence, ball lightning. Martin Uman, in his book Lightning,
discredits this theory with the references listed in his chapter on the RF
spectrum produced by lightning discharges. The frequencies are centered in
the low VHF and HF areas with very little power in the UHF bands.
Standing waves are produced between the discharge terminal and the ground
terminal (or point). As Terry points out in his excellent disertation, a
Tesla secondary inductor equipped with a large top load torus, ie, large
terminal capacitance in relationship to the distributed capacitance of the
coil itself, does not operate with standing waves. It tends to operate at
one frequency and has no transmission line effects.
The harmonic frequencies at noted by Terry in his coil at 7, 17, and 33 MHZ
can be surpressed by space winding the secondary inductor, or, as Rich Hull
has done --- going to extremely large capacitance top loads to force the
resonator to operate at a single fundamental frequency without a lot of HF
One final note -- the potential distribution along a sec coil operating
with a large cap top load is nearly linear in nature and does not simulate
a sine wave. We have measured this effect with some experiments in early
1970 when we also started using large capacitance top loads to reduce these
undesireable harmonics and boost potential output on our larger systems.
I trust this information is of assistance to this thread.
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: Best sparks
> Date: Friday, July 03, 1998 11:33 PM
> From: terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
> Sent: Friday, July 03, 1998 11:12 AM
> To: Tesla List
> Subject: Re: Best sparks
> Hi Richard,
> you wrote:
> >From: Richard Hull [SMTP:rhull-at-richmond.infi-dot-net]
> >Sent: Wednesday, July 01, 1998 11:58 PM
> >To: Tesla List
> >Subject: Re: Best sparks
> >Tesla List wrote:
> >> ----------
> >> From: terryf-at-verinet-dot-com [SMTP:terryf-at-verinet-dot-com]
> >> Sent: Tuesday, June 30, 1998 8:49 PM
> >> To: Tesla List
> >> Subject: Re: Best sparks
> >> What I suspect is that once the arc breaks out, it needs
> >> current very quickly to sustain and help the arc. In order to get
> >> current out fast, the top capacitance should be able to deliver charge
> >> maximum speed. This event is fairly local to the top terminal and the
> >> surrounding charged space. There should not be too much coupling back
> >> the secondary ground except by capacitance around the secondary.
> >> It is obvious that arcs have very powerful high frequency
> >> oscillations. We don't quite understand why but it is probably best
> >> those oscillations occur. When the top discharges at high speed it
> >> causing high local field stresses that help push the arc to greater
> >> Terry Fritz
> >I think the source of most of the high frequencies were identified over
> year ago
> >on this list. It is the arc itself creating a new resonating antenna of
> its own
> >every varying length. This is most definitely modified by the large
> >capacitance. Tesla noted similar happenings in his 1899 Colorado
> >Typical ranges are from a low of 5mhz to a high of over 200mhz.
> on about
> >a billion variables.
> >I hope no one still thinks that the resonant frequency of the coil is
> >of all the electrical energy the visible arc channel of a TC! Lots of
> >unpulsating single polarity DC is to found in and around sparking TC's
> >Remember the TCBOR electrometer measurements of 1996 and 1997? The 100
> >rotored DC electrostatic motors run up to 500 rpm using a tesla coil in
> 1997? The
> >charging of a .1uf, 30KV capacitor from a TC in 1996? A TC at full
> >DC to light! Many of the mechanisms are supposedly well understood.
> >simple physics laws coming into play in an insane web of chaotic,
> >adjusting, multipathed events over often microsecond and submicrosecond
> >frames. Attempting to following all the paths will simply make you nuts
> > Lightning is a prime example of self excited resonating arc channels.
> >hundreds of streamerlets, leaders, etc give lightning a very wide range
> >frequencies.....DC to light!
> >Richard Hull, TCBOR
> My experiment that I wrote the paper on concerned very short arcs to
> Assuming the 1/4 wavelength of the arcs was 3 inches, the frequency would
> work out to ~1000 MHz from the arc channel antenna mechanism you mention.
> Far too high to explain the frequencies I was seeing.
> A spectral analysis of the arc envelope indicates there are three
> frequencies that make up the arc. They are at 7,17 and 33 MHz.
> Actually, I eliminated 999,999,997 of the billion variables and I do know
> what causes them.
> The 7 MHz component is the discharge characteristic of the 12 pF top
> terminal and the arc resistance. 1 / ( 2 x pi x r x c ) which is 1 / ( 2
> pi x 1200 x 18pf ) which equals 7.4 MHz in the experiment.
> The 17 MHz component is the similar effect from the small sphere I used
> hold the discharge rod (shown in the paper) It is 8pF at 1200 ohms arc
> The 33 MHz component is what has me concerned and started the original
> I believe it is caused by the top terminal running out of current
> capability and starving the arc. If true, then fixing the top terminal
> that it can deliver the current smoothly should help the arc. Thus, my
> original question concerning how different terminals affect the arc
> I have seen very high voltage fields produced by arcs. Much higher than
> original top terminal voltage. I am trying to find a way to optimize
> effect and try to get longer arcs. I suspect that discharging the top
> terminal with maximum efficiency will help this effect.
> Although there are many frequencies and DC charges hanging around TCs, I
> find that they are not DC to light. There are only a few big peaks here
> there. I have followed all the frequencies to their source but I still
> not gone nuts. But I am still trying! :-))
> Best regards,
> Terry Fritz