from misty memories:
The parameters of a TC at very low power can be determined entirely by
theory,
when voltage is increased there will be corona discharge that will
significantly increase capacitances,
this primarily occurs when a radius of curvature is less than about 1mm per
3kV.
I am specifically thinking of the thin upper part of the trumpet coil.
...........................................
I know of only two applications for a TC
1 edutainment
(sparks and arcs)
2 transmission of power or information
(minimal discharges)
Mr. Tesla was interested in #2
but #1 gets sponsorship.
On Fri, 6 Mar 2026, 23:34 David Thomson, <aetherwizard@xxxxxxxxx> wrote:
> I would like to invite technically minded builders to look at an experiment
> involving a tapered ("trumpet") Tesla coil geometry and a two-channel
> measurement method.
>
> The objective is to compare two quantities measured in the same resonant
> device:
>
> 1.
>
> an electrostatic carrier derived from the topload capacitance and peak
> voltage
> 2.
>
> a magnetic-mode proxy derived from the base current
>
> The experiment compares how these two quantities scale as the drive level
> and geometry change.
>
> Important note on geometry:
>
> The "trumpet" coil is a secondary whose radius gradually decreases toward
> the top. In other words, the flare points downward toward ground and the
> smaller diameter is at the top near the topload. The taper helps distribute
> electric field stress and tends to stabilize operation before breakout.
>
> Measurement definitions
>
> Electrostatic channel
>
> q = C_top * V_pk
>
> Magnetic channel
>
> Q = kappa * I_pk
>
> where
>
> C_top = effective topload capacitance
> V_pk = peak topload voltage
> I_pk = peak base current
> kappa = calibration factor obtained from the toroidal magnetic field B_phi
> near the base region
>
> In the Quantum Measurement Unit (QMU) framework there is an additional step
> because capacitance is inversely related to potential. The measured voltage
> and current therefore must be converted through the charge conversion
> factor (CCF):
>
> ccf = e_emax^2 / e
>
> The CCF converts between conventional charge-based units and QMU units. In
> practice this means the measured potential and current channels are scaled
> by the CCF before comparing the electrostatic and magnetic quantities.
>
> After applying the conversion, the experiment tests the relation
>
> Q^2 = q^2 / (8 * pi * alpha)
>
> where alpha is the fine structure constant.
>
> The extracted value
>
> alpha_extracted = q^2 / (8 * pi * Q^2)
>
> can then be examined while varying
>
> -
>
> drive power
> -
>
> coupling
> -
>
> secondary geometry
>
> If the ratio remains constant across these changes (within measurement
> uncertainty), the two channels scale together in a nontrivial way. If the
> ratio varies strongly with geometry, the effect reduces to conventional
> resonator behavior.
>
> Required measurements
>
> C_top
> V_pk
> I_pk
>
> C_top can be obtained using low power resonant shift measurements or VNA
> fitting.
>
> V_pk can be measured with a calibrated capacitive divider or other HV
> measurement method.
>
> I_pk can be measured with a current transformer at the base of the
> secondary.
>
> Calibration of kappa can be done using a small magnetic probe to map the
> toroidal magnetic field B_phi(r,z) near the base.
>
> Important experimental condition
>
> Runs should be performed in a no-streamer regime. Once streamers appear the
> electrostatic channel becomes contaminated and the measurement is no longer
> reliable.
>
> The full experimental description is available here:
>
> https://zenodo.org/records/17408713
>
> I would especially appreciate feedback from experienced builders regarding
>
> -
>
> reliable high-voltage measurement methods
> -
>
> practical techniques for determining C_top
> -
>
> magnetic probe methods for calibrating kappa
> -
>
> any pitfalls in the measurement protocol
>
> If anyone on the list is interested in attempting a replication
> measurement, I would be glad to collaborate and compare results.
>
> Best regards,
>
> David Thomson
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>
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