Re: A new Tesla coil and k measurements

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

Original poster: "Paul Nicholson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>

Antonio wrote:

 > The prediction of the coupling coefficient didn't work very
 > precisely (designed: 0.105; measured 0.117),

You can expect a difference in the high frequency coupling
coefficient when the secondary is lightly loaded.

The calculated k and M should agree well with measurements made
using line frequency currents.  But as you say, the secondary
current at resonance will be non-uniform so the effective k will
likely differ.

In section 6 of

  http://www.abelian.demon.co.uk/tssp/pn1401.html

the coupling is treated as a distributed quantity, and as such is
represented by an integral operator.  The effective k is taken to be
the square root of the determinant of this operator.  Actual beat
waveforms are accurately described by this model.

 > Do programs as Fantc, Acmi, and Mandk take the current profile
 > into account?

Acmi and Mandk assume uniform current. Although acmi can be told to
use a given current profile, it will not compute what that current
profile actually is.  Fantc does compute the current profile (when
doing a resonance analysis), and will report the effective secondary
self inductance based on that computed current as 'Les'.

At present fantc doesn't do a distributed analysis of the joint
primary-secondary resonance, which it would need to do to report
the actual mode frequencies and k-factor.  Some of section 6 would
need to be implemented in the geotc library.

If you're going to do some accurate measurements it would be nice
to run the tssp model on the system.

--
Paul Nicholson
--