Observation of microwave volume plasma ignition in ambient air

A pulsed microwave (MW) plasma was maintained in a waveguide with an ignition pin. Images of the MW discharge were recorded during ignition in ambient air with millisecond time resolution and correlated with measurements of absorbed MW power. This work is focused on the quantification of ignition stability and observation of the plasma structure. Additionally, a time-and space-integrated emission spectrum in the range 220-770 nm is presented.