On Wed, 11 May 2011 22:26:38 -0400, "Existential Angst"

[...]

You may have solved the problem, but it is still not clear what the problem
was.
Cavitation was certainly not the problem, cuz, well, this wadn't cavitation.
It is highly unlikely that it was a mechanical collision effect, of the
formed bubbles.
I think it was some unanticipated chemical reaction, that is avoided by
shifting geometries.
The colliding hydrogen might be forming something of an electrochemical
short circuit, as well.

Anyway, souinds like a fascinating project.

My understanding of cavitation is that it is simply formation of gas
pockets in a liquid and their collapse. The gas can be anything, air
and water vapor being the most common.

I have counted several different ways these pockets (or bubbles) can
form not including introducing the gas in the way I do. The damage is
done by the bubbles collapsing suddenly, not by their collision. It is
particularly pronounced at a fluid/solid/vapor interface where the
bubbles collapse in a way that produces fluid microjets directed
towards the solid surface - a perfect fit for my case. That there is a
significant amount of energy generated by this happening I have
demonstrated adequately.

Not too sure what you mean by "electrochemical short circuit".

All in all, I tend to lean towards the Occam's razor on this one.

Michael Koblic,
Campbell River, BC