interrupter

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Mike Nolley by way of Terry Fritz <twftesla-at-qwest-dot-net>" <nolleym-at-willamette.edu>

    This is a question for anyone who might know specifics about the
Wehnelt interrupter.  The Wehnelt cell was used
as an interrupter in early spark discharge circuits.  A small platinum
electrode interrupts the circuit when gas
formed through electrolysis forms around it.
    I am in the process of designing a crowbar circuit for a pulse
discharge application, and I was wondering if the
Wehnelt cell might be useable in place of the ignitron.  I am concerned
about finding a reasonable price for the
ignitron, and the potential for mercury contamination if it explodes.
Solid state crowbars at this voltage would also
be too expensive.  My idea was to put a Wehnelt cells in series with the
discharge path so that it would interrupt the
pulse after a few 10's of  microseconds.  I need a short pulse that will
eliminate ringing between the pulse discharge
capacitors and an inductor.  I am hoping that since the pulse will be large
the cell won't re-connect before the pulse
is over.  Also, since the cell acts as sort of a point-contact rectifier,
no ringing will occur.  My questions are:
is the Wehnelt cell capable of interrupting a large DC pulse like this,
(without destroying the electrodes, container,
and splashing sulfuric acid around) and/or: if it won't work, is there a
type of crowbar circuit which might work
instead?
            --Mike