Ignition of flammable gas/air mixtures by sparks from 2 MHz and 9 MHz sources

Measurements have been made of the voltages and powers required for the radio frequency (r.f.) spark ignition of various gas/air mixtures. The spark-ignition chambers (s.i.c.) used were make-and-break mechanisms, hereafter called `breakflashes¿, employing tungsten wires scraping over a grooved cadmium disk or rod. The breakflashes were connected to the r.f. sources by means of a resistive L-type attenuator which damped any overshoots in the output voltage and resulted in a resistive 50¿ source impedance being seen by the breakflash. Measurements were also made with a quarterwavelength long antenna between the r.f. source and the breakflash cell. The high impedance seen by the breakflash resulted in ignition at available power levels significantly lower than with the directly-connected sources.