This paper describes a high-intensity, high pulse-repetition-rate picosecond-pulse excimer laser system and plasma x-ray source, which generates up to 3 W of average x-ray power, into 2(pi) steradians, in a spectral band from 10-16 angstrom. The XeCl excimer laser system output, at 308 nm, consists of a train of 16 pulses, each approximately 45 ps in duration and spaced by 2 ns. The energy of each pulse in the train is approximately 25 mJ, and the pulse-train repetition rate is 60 Hz. Each pulse in the train is focused to a spot of < 10 micrometers diameter on a metal tape target, resulting in an intensity of 1 X 1015 W cm-2. Spectral and spatial characteristics of the x-ray emission have been studied, and the laser energy to x-ray dose conversion efficiency has been measured in an experiment which simulates the x-ray lithography process. Lithographic efficiencies of 5.9% and 10.9% have been measured for copper and stainless steel targets, respectively.