Polarized HV/ what's + and what's -

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Original poster: "David Rieben" <drieben-at-midsouth.rr-dot-com> 

Hi all,

I recently scored a pretty nice x-ray transformer. I think it's
rated around 150 kV -at- ~ 600 mA. I've already repaired a
carbon tracked phenolic rectifier mount twice. The new
phenolic mounting block also carbon tracked after the
first repair but so far the second repair has held up (keep-
ing my fingers crossed). Anyway, I'm wanting to keep
the rectifiers intact in this transformer since I'm wanting
this one as a very high DC voltage source. Since I have
it all back together after the last repair I really don't want
to dig into the oily mess again just to get a close look at
the diodes to determine the polarity of the HV outputs. I
have heard that one polarity tends to form corona easier
and actually arc further at a given voltage than the other.
I've noticed this phenomena from the output leads of this
transformer as I slowly ramp up the input voltage to it with
a big variac. Of course I'm also seriesing the variac's out-
put to it with a ballast assembly since x-ray trannies are
NOT current limited. Anyway, I was thinking that the ne-
gative terminal would be the one that would most likely
tend to more corona and arc further at a given voltage
but I simply can't remeber for sure. I think Antonio de
Quieros was talking about this once. Can anyone tell
me which polarity will form more corona and arc further
at a given DC voltage?

Thanks,
David Rieben