RE: TC Spark Energy

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

Original poster: "John H. Couture" <couturejh-at-mgte-dot-com> 


David -

I like to distinguish between sparks to ground and streamers that terminate
in the air. The length of streamers in air are random and can not be
controlled. The length of sparks to ground can be controlled and the number
per second assumed to be 120 or 100, etc. I agree this is debatable.

Energy per spark length is useful because it can be an indication for rating
a TC.
Input power per streamer length has problems. Power is an instantaneous
parameter and streamer length is random. Shock frequency is a term I have
never heard before so cannot comment on it.

Can you show the calculations for comparing a 1000 watt TC with a 500 watt
TC using your method?

John Couture

----------------------------





-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, March 09, 2004 7:21 PM
To: tesla-at-pupman-dot-com
Subject: RE: TC Spark Energy


Original poster: "David Thomson" <dave-at-volantis-dot-org>

Hi John,

Energy per streamer (I prefer not to call it a spark) would not be very
helpful.  The energy per streamer would be equal to the input voltage times
input current times the duration of time the coil was in operation.  The
input energy is continually increasing over time but the streamer length
remains fairly constant over time.

Here's a theoretical dimensional analysis for quantifying the streamer...

A more effective measurement would be input power per streamer length.  I
can't find my source at the moment, but this works out dimensionally to a
unit of "shock frequency".  It is an entirely mechanical unit which
describes the rate of pounding of the streamer on the atmosphere.

watt / streamer_length = shock_frequency

If we want to increase the force against the atmosphere, we would lower the
operating frequency of the secondary coil.

watt / (streamer_length * secondary_frequency) =
force_of_expansion_on_atmosphere.

The more force exerted on the atmosphere, the louder the streamer will be.
To increase the streamer length either decrease the force exerted on the
atmosphere, or lower the secondary coil frequency, or both.

watt / (force_on_atmosphere * secondary frequency) = streamer_length

It may be possible to quantify the force on the atmosphere in terms of air
pressure, temperature, and relative humidity.

The efficiency of the primary and secondary coupling along with materials
and construction technique will affect how much input power is converted to
output power.  The shock frequency equation for input power is intended to
be a benchmark of the overall Tesla coil efficiency, which is what you seem
to be looking for.  Such a benchmark will make it possible to compare a
1000watt Tesla coil to a 500watt Tesla coil as we are looking at a ratio of
power to streamer length.

Dave

  > -----Original Message-----
  > From: Tesla list [mailto:tesla-at-pupman-dot-com]
  > Sent: Tuesday, March 09, 2004 1:49 PM
  > To: tesla-at-pupman-dot-com
  > Subject: TC Spark Energy
  >
  >
  > Original poster: "John H. Couture" <couturejh-at-mgte-dot-com>
  >
  >
  > For over twenty years the coilers on the List have used output
  > spark length
  > to compare their coils. The input is usually shown as a total input
watts.
  > The problem is that this does not give the coiler any indication of the
  > actual energy per spark to give a true comparison of Tesla coils. To my
  > knowledge no coiler (see below) has ever determined the TC input energy
  > (joules) per spark for these comparisons. Do any coilers know how
  > this could
  > be best accomplished?
  >
  > The overall engineering efficiency is represented by
  >
  >     Percent efficiency = 100 x Spark Length/Input Energy (joules)
  >
  > The spark length could be in centimeters, inches, etc, and the
  > input energy
  > in joules or watt-seconds. The energy in the spark output is a complex
  > parameter so would have to be a compromise. In past postings the
  > approximate
  > losses in the TC system have been determined and the
  > characteristics of the
  > spark have been estimated. The preliminary tests I have made gave  8.5
  > inches (21.59 cm) per joule of input energy. Has any other coiler
  > made these
  > tests?
  >
  > John Couture
  >
  > --------------------------------