[Amps] Vacuum Variable Capacitor Questions

[Larry Benko]

I have some known good vacuum variable capacitors that I would like to 
use in a couple of home made antenna tuners.  The capacitors all hipot 
at more than the specs with leakages of only a few uA.  How robust are 
the caps. to arcovers?  For a tuner with air variable capacitors trying 
to match problem impedances my amplifier very quickly sees the bad SWR 
if an arcover occurs and shuts down.  No harm appears be done to the air 
variable capacitor as the arc only lasts a fraction of a second.  Then I 
just reduce the power and continue.  Is the same true for a vacuum 
variable capacitor or is some permanent damage done to the capacitor?  
In no case am I getting close to the maximum current rating of the 
vacuum capacitor.

Thanks and 73,
Larry Benko, W0QE