I have a suggestion for preventing resonant charging when
using a NST that was inspired by a question put to the Tesla-2 list.
Inserting a fullwave rectifier between the transformer and primary
cap should do the job since it prevents the cap discharging back
into the transformer and allowing the secondary to resonantly swing
to ever higher voltages. It won't stop the peak cap voltage from
reaching 2x the RMS transformer voltage but that is as far as it can
go. In other words, if you use a fullwave bridge and your static gap
is set wide enough to prevent firing, you know your transformer is in
danger. It *may* also block gap transients from reaching the
transformer if the diodes are ultra fast types perhaps (speculation).