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Re: Arc length vs pwr
>Date: Wed, 16 Oct 1996 22:25:25 -0600
>From: Tesla List <tesla-at-poodle.pupman-dot-com>
>To: Tesla-list-subscribers-at-poodle.pupman-dot-com
>Subject: Re: Arc length vs pwr
>Reply-to: tesla-at-pupman-dot-com
>>From MALCOLM-at-directorate.wnp.ac.nzWed Oct 16 22:23:39 1996
>Date: Wed, 16 Oct 1996 09:37:39 +1200
>From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
>To: tesla-at-pupman-dot-com
>Subject: Re: Arc length vs pwr
>A quick comment on this:
> I think arc length would have to obey a square law at least as
>far as upping power is concerned. The longer the spark, the more
>power dissipated along it both in maintaining ionization (width) and
>length (series resistance). I think one further order of power loss
>occurs in the gap when upping power levels. I do think though that
>primary things can be tailored to reduce this loss - it will be
>different for different gap systems in my opinion.
>
> On the lumped vs distributed thing for the secondary: the more
>top-C you have, the more lumped it gets as the secondary current
>becomes uniform and hence 0.5LI^2 applies. That measure of magnetic
>energy cannot apply in a distributed circuit as the current is not
>uniform along the length of the coil. There would be (in my opinion)
>an optimum top-C for a given secondary and bang size because several
>things happen while increasing terminal capacitance: (1) the
>secondary inductance is becoming more effective (Q increases), (2)
>voltage holdoff is increasing (assuming more C = greater radius of
>curvature (ain't necessarily so), and (3) output will eventually
>decrease due to energy limitation. It would be jolly nice to quantify
>this optimum R.O.C. and size.
>
> On tuning: there is one subtlety I have used where Lp and Cp are
>more-or-less fixed: raising and lowering the top terminal can
>dramatically alter secondary fr.
>
>fwiw,
>Malcolm
Malcolm, Richard Hull, All,
One thing I've noticed playing around with the height of the final
large toroid above the secondary in my MTC system is a tendancy to
produce more strikes to earth with the toroid closer to the secondary, and
seemingly more streamers shooting outwards or straight up in the air with
the toroid placed 3 inches higher. I have only one test run under my
belt where I seemed to notice this effect and at the time I chalked
it up to an effect of varying the e-field control, but perhaps there
is more in this? If the Q has been changed, the theoretical final
voltage will be changed as well, although this becomes clamped to whatever
as soon as a streamer appears, _ BUT_ , the voltage gradient at the surface of the
toroid _IS_ determined by the field shaping and therefore will alter
to some degree the breakaway voltage for a given radius of curvature toroid.
So by varying the height above the secondary we are not only
changing the voltage developed by the change in Q, but we are
changing the breakaway voltage of the toroid by the change in
electrostatic field control around it. Isn't it nice trying to
analyze several interwoven variants changing at the same time?
One thing is certain to me at this point at least. I have ample experimental
evidence of how certain topload shapes can be made which do a much better
job than a simple toroid to deliberately throw streamers upwards
through modified electrostatic field control. Trouble is, I
rather enjoy those white hot lightning strikes to earth! : ) My goal
with using what I am learning about the e-field topload control then is to be able
to input more power with this strategy so that the innevitable strikes to earth
will occur farther out from the coil tower, and hopefully avoiding self strikes
which are such a nuisance and potential source of system damage as
powers are increased to more and more exciting levels.
fwiw,
rwstephens