Experimental methods enabling the efficient control of high pressure microwave discharges

High pressure microwave discharges (150 Torr to one atmosphere) have been the focus of numerous recent experimental investigations such as microwave plasmoid/microwave fireball investigations 1 , microwave plasma assisted combustion 2 , and microwave plasma assisted gas reforming, and also recent commercial applications such as CVD diamond synthesis 3 . In each of these experiments discharge control and the coupling efficiency become very important as the pressure is increased. This is especially true as applications move toward commercial realization.