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Re: TC Electrostatics

12/7/96

Conclusion:  The Tesla Coil is a major electrostatic device.

A series of experiments were preformed measuring TC base current as 
measured with a Weston Thermo-galvanometer and various components in 
series.  The meter and all components were placed in series with the TC 
base.  Again, the square root of meter reading was not taken, even 
though the meter measures I^2.

The variac was adjusted (~60 vac) for 90 ma meter reading.  The spark 
discharge appeared the same as with no meter in series.  Forward 
conducting, reverse conducting and back to back blocking diodes were 
placed in series with the meter and TC.  The spark discharge appeared 
unchanged and meter currents were 80 - 90ma.  The diodes were checked 
with DC and appeared good afterwards.

A 22 uH ceramic roller inductor was place in series.  The spark 
discharge appeared the same as originally and meter currents were 90 - 
95 ma.  This coil was off axis to the TC secondary and did not appear 
to affect tune or TC output.

A 50 pF 35 kV fixed vacuum capacitor was placed in series.  Spark 
output decreased markedly and meter current read 20 ma.  This was off 
axis capacitance for the TC secondary and did not participate in the TC 
field.  Attempts to retune the TC primary made little change in output 
and base current.

The coil was fired without a secondary ground connection and Richard is 
right that the TC seeks ground/counter poise with a vengence.  The base 
of secondary arced ~ 3" - 4" over a plexiglas barrier to the TC primary 
coil.  Of course, this is a straight shot to the neon secondary.  I 
stopped it immediately.  Neon still fires, for now anyway.

Assessment:

Blocking EM base current with diodes has little affect on the coil 
output.  My next experiment is to confirm with a current shunt and 
scope that EM is truely blocked with the diodes.  If the diodes blocked 
any EM and EM is the major electricity (really basic term) responsible 
for TC output, then there should have been some indication of decreased 
output. This doesn't appear to be the case.  Note, as in measuring TC 
output with the ESVM, it appears that diodes permit passage of 
electrostatic charge.

Adding series inductance made no real change.  It is off axis and did 
not appear to change tune, spark output or base current.  Inductance 
should imped EM current at RF frequencies and if EM is responsible for 
TC output the output should have decreased.  The output did not 
decrease.  The inductor should easily conduct DC and presumably 
electrostatic charge.  Since base current and coil output were 
unchanged with increased inductance it is good evidence electrostatics 
may be involved.
 
My first impression of decreased spark output and decreased base 
current using the 35 pF capacitor in series was that the coil was out 
of tune.  Retuning didn't change much.  It's noted that the capacitor 
is off axis and does not participate in the TC field or function.  It's 
my impression that this added capacitance just gets lumped in series 
with the earth capacitance.  The cap presumably should conduct most of 
the EM current, but block DC current and presumably electrostatic 
current.  Again, if EM current was primarily responsible for TC output, 
the output should not have decreased so drastically.  

These findings are qualitative and preliminary.  Much work and 
verification must be done.  Correct tuning with and without added 
capacitances and inductances must be verified.

It appears there are two basic currents in Tesla coils.  The TC 
secondary is coupled to the the primary driver and of necessity energy 
is transferred primarily by electromagnetic induction.  Resonating coil 
energy and TC ouput appear largely electrostatic in nature with a 
secondary EM component.

RWW
RWW