Re: Sparks jumping from 4' to 9' (was Re: 20 joules)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>


> what about powerfull cw coil? or powerfull
> disruptive coil, working in a
> field of cw one? :-)

Well maybe, but I don't see any reason to maintain the
field for longer than needed for the leader to finish
its growth. Empirically, that seems to be somewhere in
the region of 10-50 microseconds per foot. Once it's
grown as long as it's going to (ie the tip has reached
a region where the E-field is too low to drive growth)
you can shut the drive off to save power.

Terry quoted Bazelyan and Raizer as growing 450ft
sparks with a 1ms pulse from a Marx generator, which
is only 2.2us/ft, but I think Tesla coils need at very
least three times longer than a Marx bank to shoot the
same distance.

The reason: Scope captures suggest that a TC leader
doesn't grow all the time, but only around peaks of
the output voltage waveform. A Marx bank, having a DC
output, will grow it continuously.

Steve Conner