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Re: 100 meter sparks (picture of GE machines!)
From: Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
Sent: Friday, October 31, 1997 3:14 PM
To: Tesla List
Subject: Re: 100 meter sparks (picture of GE machines!)
>
> > To: Greg
> >
> > It was a Marx generator. The chief clue here is there is a spark
discharge
> > seen at each stage in the photo --- a Cockroft-Walton uses diodes not
spark
> > gaps as the switching device hence no spark gap at each stage. Also
note
> > the sphere gaps on each stage -- again indicating Marx generator. A
large
> > tube type rectifier power supply charged each stage --- 1 power supply
for
> > each generator and total of +5 MEV and -5MEV on other unit.
>
> Thanks -- you answered my next question as well, which was how did they
> charge
> the bank with AC if it was not a 120Hz unit?
Marx generators don't have a separate power supply for each stage. They are
charged through the resistors between the stages (or inductors in high
rep-rate applications for lower loss).
Perhaps what is referred to is a Greinacher cascade using tertiary windings
on the power transformer of each stage. The tertiary winding feeds power to
the next stage up the chain. The advantage is that each stage only needs to
be insulated for the stage voltage.
However, as the writer points out, all those sphere gaps generally
indicates a Marx bank, which only has one charging supply for the whole
stack. Of course, the gaps could be part of a big multipole shorting
switch as well.