vacuum spark gap over unity?

[hoptoad]

can u explain why unbroken 12v filament did not light up....?

In two words - "impedance matching".  In more words ......

The 2kV supply source is very likely a high impedance output, and the broken 12 v filament bulb is a perfect high impedance load to suit it.

Spark gaps are a plasma phenomena* whereby the initial resistance of the air gap (or other gas) is high. A high enough voltage is initially required to break down the resistance of the gap,  until an arc appears. Once an arc is established, it can be sustained with low voltages.

If the high voltage drops too low after establishing an arc, the arc will cease. This will create an oscillatory arc, as the supply voltage rises until it reaches breakdown voltage again, re-establishing an arc, which then ceases due to low voltage etc .......

However, an unbroken 12V filament will be a low impedance load, and will immediately, when connected, cause the the high voltage of the supply to drop dramatically. The internal impedance of the supply, being high, will limit the current available to the low impedance filament.

There will be both, insufficient voltage and insufficient current, to normally power the light, due to the high impedance of the supply and the low impedance of the globe.

*The most obvious example of this plasma phenomenon, already put to good use, is the ubiquitous florescent tube lighting system.  This system makes use of high starting voltages, followed by lower running voltages, and was invented by Nicola Tesla. His florescent lighting system is still in use everywhere around the world today.


Cheers