Debris eliminatio in a droplet-target Baser-plasma soft x-ray source

A tabletop high-brightness line-emitting laser-plasma soft x-ray source utilizing single microscopic droplets as target is shown to produce several orders of magnitude less debris than conventional-target sources. Quantitative measurements of debris deposition rates and x-ray flux at different directions around the droplet plasma are presented. With ethanol droplets and a 10 HZ, 70 m.l/pulse laser, typically 1 X lo’* photons/(s’r~pulse~linej are emitted from the C V and C VI lines in the water window. The debris deposition is further reduced with a small, localized gas jet shield, which is transparent to the x-rays. The deposition rate through the gas shield has been determined to be -0.2 pg/(sr.pulse). Thus, this droplet-target laser-plasma x-ray source is four orders-of-magnitude cleaner than a low-debris plastic tape target laser plasma of similar brightness, making, it usefu! for x-ray microscopy and lithography.