Re: Tesla Coiling / High Voltage Research Topics

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

Original poster: Paul Nicholson <paul-at-abelian.demon.co.uk> 

Just picking up on this thread from last week.

Dan wrote:
 > i am asking the group if anyone knows of any particular areas
 > which may be research worthy

Hi Dan,  I can think of many things that ought to be examined,
measured, developed.  So many, perhaps, that it's hard to know
where to start!

IMO the most important area concerns interaction of discharge
loading with the topload.  Information about the kind of load
impedance presented by different types of discharge would allow
TCs to be designed to make the best use of the available input
power.

But this is a large and difficult area and realistically we can
only nibble at pieces of the problem.  To break into this area
there is one particular preliminary challenge: to accurately
measure the topvolts during breakout.  We can already measure
discharge currents fairly well, using optically isolated current
probes in the discharge path.  But to analyse the load impedance,
we need to digitise both a current and a voltage waveform.

The problem is to fit a probe to the TC which will respond
proportionally only to the terminal voltage. Such a probe must not
be decalibrated by things like space charge, and it must not
respond to the charge on the coil or other parts of the system.

Well that's just one topic.  There's loads more, many of which
involve just small signal measurements such as Q factor and input
impedance.  These may be more to your taste.

For example, tssp documentation makes a clear distinction between
the effective shunt capacitance Ces of a secondary, and the energy
storage capacitance, Cee.  Programs such as JavaTC will predict
these two quantities for a given coil, and there are various
formulas offered in tssp docs which relate Ces and Cee to Zin, Q,
base current and top voltage.  A small number of measurements have
been made on these quantities and these tend to confirm the
predicted relationships.  But we're lacking a set of thorough
and accurate measurements which would unequivocally drive home the
validity of these equivalent capacitances.

So there's two examples at opposite ends of the spectrum.
There are lots more areas too, but the measurement of topvolts is,
for me and the tssp project, the major holdup at the moment.
--
Paul Nicholson
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