I was watching this video made by ludic science and at 3:14 he said that at the maximum output of the high voltage ignition coil, the distance was 10mm/1cm which he claimed to be 10-12kv. Isn't the gold standard for the breakdown voltage of air 30kv/cm? Can someone explain?
There is a big difference in dielectric Breakdown Voltage BDV for smooth parallel surfaces and point sources from sharp wire tips due to the E-field gradient force effects on ionization.
Yes 30kV/cm or 3kV/mm is true for smooth area surfaces.
But for wire tips it is 10kV/cm or 1kV/mm This also raises the resistance and this begins arcing with a lower current, which is less visible.
This of course varies with dust , humidity and pressure.
This BDV has nothing to do with the "holding current" gap which may be increased after conduction occurs.
The guy says that at maximum power, the distance of the arc is around 10 mm but, in order to initiate that arc he moves the electrodes to a much smaller distance i.e. he lowers the distance to "start" breakdown (about 5mm). Once breakover has occurred, the arc can be drawn to a greater distance. That is what you are seeing.