I don't understand what you mean here. Are you saying 50 volts per .001 inch? I thought this was the approximate figure for air. Also, how much of a vacuum are you operating at (how many torrs)? [stuff snipped] > Original Poster: "unicorn" <unicorn-at-telerama-dot-com> > > HELLO, > > I made a vacuum box and it work fine for me. > The spark will jump at a lower voltage, mine jump at 50 volts. > > > kid-kv >