Pulsed microwave discharge: a very efficient H atom source

We describe a very efficient source of H atoms generated by a low-pressure (1 Torr) pulsed microwave discharge (2.45 GHz). We show that the low mean microwave power density applied in pulsed discharge limits considerably the heating of the discharge tube wall, and hence, the loss of H atoms by wall recombination. The H atom molar ratio, measured by actinometry, increases from 30% in continuous power to nearly 100% in pulsed power, for the same instantaneous power. We present a comparison between continuous and pulsed power, both for electron density (and discharge balance parameters) and for H atom density. (author)