Re: NST implemented Cockroft-Walton Multiplier

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Original poster: "Dr. Resonance by way of Terry Fritz <teslalist-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>


A very efficient Marx cap charging system can be made using a potential
xmfr, 14.4 kV, rated 1.5 kVA.  These can be operated on the short charging
duty cycle drawing up to 4 kVA for short periods of time.   0.1 MFD caps
will work well and can be charged effectively with Fuji diodes.  We use
units rated at 9 kV and 300 mA.  They can be operated effectively in series.
Sometimes this can be used as a voltage doubler to increase the stage
potential --- energy goes up as the square of the potential so it's
advantageous to have a high stage potential.

Energy discharge caps need to be effectively charged in relatively short
periods of time and then promptly discharged.

Stage separation resistance on the order of 50K to 75K on each side of the
charging ladder work well to provide effective isolation during the
discharge period.

Another important element is to use a solenoid type device to disconnect the
charging power supply prior to firing.  This is usually accomplished by a
solenoid operated with a very long moment arm in air or under oil
(preferably).  A standard 558 (quad) timer circuit provides effective
control of this device to provide a 2-3 second disconnect after charging and
then fires the unit.

A three electrode gap can be used on the first stage, or, equally effective,
a long rotating system operating an insulating long phenolic tube which
turns all spark gaps closer for a second to fire.  The first stage spark gap
is set slightly closer to insure it's firing first.

Keep all your spark gaps in visual direct line as the UV light also helps
produce avalanche photons which assist in the breakdown event.

If you are using a Cockroft-Walton instead of a Marx then adequate
resistance rated at the full output potential must be used in series with
the output to prevent the high peak oscillatory discharge from occuring
which would damage the diodes.  A storage scope is helpful here to observe
the output waveform.  A usual value of 2-10 Ohms is incorporated throughout
the series sparkgaps to shape this waveform.  Each resistor must be rated
for full stage potential at usually 200-500 Watts depending on your cap
value.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913