Observation of extreme ultraviolet light emission from an expanding plasma jet with multiply charged argon or xenon ions

We report on the first direct demonstration of the possibility to generate extreme ultraviolet (EUV) radiation with a freely expanding jet of dense plasma with multiply charged ions supported by high-power microwaves. The detected emission power is about 20 W at 18–50 nm for argon and xenon and 0.3 W at 13–17 nm for xenon. The discharge with a peak electron density of up to 3 × 10 16 cm−3 and a characteristic size of 150 μ m is supported by the focused radiation of a recently developed gyrotron with unique characteristics, having a 250 kW output power at 250 GHz and operated in a relatively long (50  μ s) pulse mode. Up-scaling of these experimental results gives grounds for the development of a point-like kilowatt-level EUV source for high-resolution lithography, which is able to meet the requirements of the microelectronics industry.