Comparison of microwave-induced plasma sources

Abstract

Four microwave cavities/structures for spectrochemical analysis have been fabricated and tested: an enhanced Beenakker cavity, two modified surfatron-like structures and a strip line source. Each of these devices incorporated tuning improvements to enhance the microwave coupling efficiency. Preliminary tests indicated that stable discharges could be obtained in all four devices with a low power microwave generator. The operating stability range of power (0–120 W) and gas flow-rates (0–2.1 l min–1) and spectral emission properties for each device are compared with those of the conventional Beenakker cavity.