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On 9/18/18 3:43 PM, cn8@xxxxxxx wrote:
Hi--
I AM THE TRIGGERED SPARK GAP WHISPERER. Well, at least I have
significant experience. A field distortion gap is the best---easiest to
trigger and easier to build. Visualize two brass cap (acorn) nuts, maybe
3/8, spaced just beyond breakdown. A tungsten needle comes in from the side
with the point centered. The trigger pulse is fed onto the needle through
an isolation cap (a little doorknob of 100 pF or so) and the needle is
biased midway between the electrodes with two big equal resistors (>10M). A
tiny thoriated tungsten welding rod works well for this. You can grind a
point on the end. It would probably work well extending through the gap
with no needle point, if you see what I mean. Keep everything symmetrical.
A trigatron gap has the needle coming just flush through a hole in one of
the electrodes, but is much more finicky. Few if any big pulsers or Marxes
use them.
I've got examples of both. The one I used before was basically a form of
trigatron - copper pipe on both sides, solid caps on both ends, with a
hole drilled in each. Tungsten welding electrode flush with the end of
one. Air feed through the pipes, so it flows through the hole and
radially out through the gap.
I've also done a field distortion gap with a welding electrode between
two sphere electrodes (copper floats).