[no points for guessin who is behind again....]
>(a quick trip back to the lab)
>I just ran 15 amps DC through an arc between a carbon rod and one of my diamond
>shaped inserts - at first a few sparks that looked a lot like the sparks formed
>by high carbon tool steel when ground, and then a nice steady arc.
A small point, ad rem DC and arcs. A DC arc 'erodes' one electrode
faster than the other. A LOT faster. (The positive, i think.)
irrelavant to normal tesla SPARK gap operation with AC, but evaluation
of electrode material under DC conditions would, imo, be more useful
if done in BOTH polarities...
(Extended discussion of this can be found in books on arc welding, arc
light practice, etc, etc....)