Re: Need TSG help

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

Original poster: "B2 by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bensonbd-at-erols-dot-com>

Hi Steve,
    Your setup is unique and will require a bit of experimentation.  I
don't recall any such setup in the open literature.  There have been
proposals for such a spark gap "bang-bang" for military launchers, etc.  I
don't have access to that information anymore:(

    First use the smallest possible HV trigger pulse amplitude that will
just trigger the first gap.  You can use a water resistor between the
ignition coil and midplane.  Experiment with resistances.  A critically
damped pulse would be best but may lower the coil voltage a lot.  Use large
ferrite donuts between both spark gaps and the tank capacitor.  Use a small
capacitor across the second spark gap.  Try a small capacitor from the
power supply side of the first spark gap to ground.  This will act as a
return for the trigger pulse.  The return capacitor for the other trigger
should be on the side of the second gap furthest from the first gap.
Increase the spacing of your gaps until they are just barely triggerable.
And last, but not least, use a smaller tank capacitor for these experiments
and scale up slowly.  This will save on wear and tear.

    The inductance between the first spark gap and the tank capacitor may
have to be bigger than a ferrite donut.  Depends upon the strays in your
setup, etc.  A trigger isolation gap should be used as well, as Bert
suggested.  Are the copper pipes at right angles to each other (more
uniform field) ?  Are they firmly mounted?  Electroacoustical effects can
add noise at high voltages (may be irrelevant).

Cheers,
Barry


> Here is the problem.  When one of the TSGs fires, it immediately causes the
> 2nd one to fire.  Both of them firing at once is really bad news!  It
> results in a deafening, frightening BANG!! as several hundred Joules of
> reservoir cap energy is discharged through the two TSGs in series!  Very
> hard on caps, power supply and my nerves, and no energy makes it to the
> secondary.

> --Steve