Properties of a catalytically active pulsed microwave discharge at atmospheric pressure

Observation of microwave volume plasma ignition in ambient air

“…Maintaining a microwave (MW) discharge at high pressures is a challenging task, which can be interesting for a number of applications such as bio-decontamination [1], crystal growth [2], decomposition of NO in exhaust gases [3,4] and volatile organic compounds [5], hydrogen production [6][7][8], enhancement of combustion [9,10] and others [11][12][13]. The main problems are related to the high thermal energies of the plasma and difficulties with discharge ignition.…”

“…The ignition can be initialized with an external resonance cavity [3,4], but it does not support pulses with long offtime and thus the ability to control thermal load from the plasma are rather limited. A pulsed MW discharge was successfully obtained at high powers (15-100 kW, 9.04 GHz) at the end of a tungsten needle inserted into the waveguide system [6,7]. The discharge is formed from a bundle (about ten) of filaments on the top of the needle and does not occupy a large volume.…”

“…The concept of ignition pin has fundamental peculiarities and it should be distinguished from all those presented above. A resonance structure amplifies the electric field quite strongly in comparison with the metallic nozzle used in torches [11,12,23,24] or tungsten needle applied in high power discharges [6,7]. The ignition pin provokes plasmas with relatively large volume and consumes higher power in contrast to microplasmas [10,[14][15][16][17][18][19][20][21][22].…”