Aordinery tube filled with air is diode but electron eject rapidly from outer surface??

A tube is diode if it consist air[body (air)] Cathode and anode vp=cathode potential ,vn=anode potential ifyou apply law of conservation v=root 2eV/m (e=1.6*10-19 m=9.1*10-31)for  250 VOLT it comes approx 9.---*106 watch carefully the velocity difference  just calculate in mind in a sec and see what is diff !say----RADHAE RADHAE!!(9.3*106 approX!)