Re: 5MV, 15/120mA Tesla Coil

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

Original poster: dhmccauley-at-spacecatlighting-dot-com 


I seriously doubt they were even close to 5MV.  There are problems with this
that are blatantly obvious.

1.  If this was a classic magnetically coupled tesla coil, that kind of
voltage could never form on the discharge terminal (topload) of that
secondary without
first striking over to the primary at a much lower voltage.

2.  The topload would have to be absolutely huge to allow that kind of
voltage to build-up.  Small toroids would have a much lower break-out
voltage and there would be
a discharge at a much lower voltage that obtainable.

3.  Also, with only 120mA at 15kV, there is not enough power available to
get 5MV in a single discharge cycle unless you were
charge pumping a topload capacitor or similar over many cycles.  The gain is
approximately = 333 which is ENORMOUS!
Since Gain = SQRT (Cp/Cs) the secondary capacitance (self-capacitance of
secondary + topload capacitance) would have to be approximately 110,000
times
smaller than the primary capacitance!  Considering you new a large topload
to begin with to allow the voltage to build-up that high, you would have a
very large
primary capacitance and a 15kv/120mA transformer would NEVER be able to run
that.

I may be wrong here, but I think even the largest pole transformer tesla
coils (>30kW) would have trouble getting to 5MV output!


Dan


 > I read somewhere a few years ago on the TCBA newsletter (I think) about a
 > team of coilers (pro physisicts? can't remember) that made an 8"x40"
 > secondary with ~7000 turns of 42 awg. They managed still to get 5 million
 > volts out of it with if I remember right a 15/120 supply. I take it that
 > higher voltage doesn't necessarily mean longer spark, but am I overlooking
 > something else? I don't think they mentioned the output length, but 5MV is
 > hard to picture short.
 >   What if I keep the primary inductance high and add a bigger topload?
This
 > was my original idea, but was thinking that adding a breakout point
reduces
 > the effective capacitance, or does it do the equivelent of making it a big
 > leakier capacitor? Can't test this without my scope and kinda chicken to
try
 > since it's not a robust tube unit.