Re: NST implemented Cockroft-Walton Multiplier

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

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

You shouldn't be getting any ripple on the marx... because there's no load
to discharge it,
You don't need any series resistor to the first stage from the CW to the
Marx, either.. the CW stack itself serves as a constant current source.
, the voltage should climb in discrete steps, though..  And, there might be
some ripple on the bottom cap of the marx, as the charge slowly propagates
up the marx stack, but eventually, it should reach equilibrium..

If you want to model a constant current source for the charging, put a
whacking great inductor in series with your AC source pumping the CW.. Many
henrys (you can calculate it out for an NST..
OpenCircuitVoltage/ShortCircuitCurrent = XL; XL = 377*L (assuming 60 Hz)
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, May 01, 2003 6:14 PM
Subject: Re: NST implemented Cockroft-Walton Multiplier


 > Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<dhmccauley-at-spacecatlighting-dot-com>
 >
 >  > >Also, what types of values were you guys typically use for capacitors
for
 >  > >your big cap charging circuits.
 >  > >I'm currently looking at some TDK 1000pF, 40kV capacitors, and based
on
 > my
 >  > >charge current, I'll still get about 400-500V
 >  > >ripple at the marx generator capacitors during charging.  I could
reduce
 >  > >charge current, but that would increase charge time which may or may
not
 > be
 >  > >desirable.
 >  >
 >  >
 >  > You won't get any ripple at the output, because the marx capacitance
acts
 >  > as a huge filter.  Think of the CW stack, in this situation, as a
charge
 >  > pump that pumps packets of charge up the stack. When the output voltage
is
 >  > low (i.e. marx has low charge), the upper stages of the CW don't do
much..
 >  > as the output voltage rises, the upper stages start to help move the
 > charge
 >  > up the stack.
 >
 >
 > I'm not sure about that.  I have both the CW stack and the marx generator
 > very accurately modeled in PSPICE and by probing the voltage level on the
 > last capacitor (output) of
 > the marx generator, I am getting about 400-500V ripple all the way through
 > the charging cycle of the marx bank.
 >
 > I don't have a current limited source (only using a 15kVAC, 60Hz AC
source),
 > but i do have a 20Meg resistor between my CW stack and the input to the
Marx
 > Generator.
 >
 > Could I be doing something else wrong??
 >
 > Thanks
 >
 > Dan
 >
 >