Re: Tesla Coil RF Transmitter

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: William Beaty <billb@xxxxxxxxxx>

On Sun, 11 Sep 2005, Tesla list wrote:

> Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>
>
> Charges don't flow freely in plasma. The resistivity is significant.

Judgement of "significant resistivity" depends on the impedance of the
source and load.  For example, if your power supply puts out one watt, but
it puts it out at one volt and one amp, then the supply impedance is one
ohm, and your connecting wires had better have much less resistance than
one ohm, (say 0.1 ohm or smaller,) otherwise your energy will all go into
wire-heating.  In other words, your 1V/1A power supply thinks that the
division between conductor and insulator is centered at the value of one
ohm.  A 100 ohm leakage path is nearly an insulator, since it dissipates
only 1% of the output wattage.

BUT suppose instead
that your power supply puts out one watt at one kilovolt and one milliamp,
In that case the supply impedance is one megohm, and your connecting wires
had better be 100K or less in resistance.  In that case a 10K resistor
is a conductor of negligable resistance!  And a one-meg leakage path will
eat up half the power supply output!

So if Tesla's power supply puts out a megawatt at 1MV and one amp, then
100K is a fairly good conductor, and insulators have to measure 10Megs or
better.  In that case you could create a vertical antenna tower out of
plasma, and if the plasma filament measured 10K, it would only eat up 1%
of the power supply's output wattage.

And if the TC emits 100 megavolts at 10mA (still 1 megawatt,) then the
supply impedance is 10,000 megohms, and the "plasma tower" antenna can act
as a negligable series resistance even if its resistance is 100 megohms!





> The wavelength would be 12 km. Something smaller than about 1 km would not
> irradiate much.

If the Z is mismatched so the output wattage is low, simply crank the
output voltage proportionally higher.  An antenna tuner typically does
just this when matching to short antennas.  But then you have some losses
because the resonator coil gets hot.  Better to use a quarter-wave
vertical, but if your antenna is electrically short, then you have to dump
energy into coil heating if you want to emit energy into space.  It helps
to use expensive silver Litz wire coils, cool them with refrigeration or
dry ice, etc.  Identical issues arise at the receiving end, of course.
Tesla REALLY needed some room-temperature superconductors!




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William J. Beaty                            SCIENCE HOBBYIST website
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