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Re: supercaps

I remember many years ago
learning that high voltage capacitors are hazardous because thermal
processes will cause them to become polarized over time even if they
are initially "discharged".

I think this is an incorrect interpretation. Brief contemplation of
the Boltzmann factor associated with the spontaneous fluctuation of a
newly made capacitor to a kilovolt or so will convince all but the
very most cautious (who wear oxygen masks in small rooms against the
possibility of all the air molecules piling up in one corner) there
is no danger. The danger lies in the rebound phenomenon. If the
capacitors have ever been charged to high voltages and then discharged,
residual polarization with long relaxation time can bring them up to
a good fraction of their former voltages. It is the same phenomenon
seen with old picture tubes.