Strong anomalous emission from He-like and H-like Ne in short-pulse laser-driven plasmas

We observe strong emission-from the 1s(2)-1snp Rydberg series in He-Like Ne and from the Lyman-cu transition in H-like Ne. These emissions are observed when 1.05-mu m light in a 600-fs laser pulse is focused into the dense, localized output of a pulsed supersonic nozzle. The maximum focal irradiance of our laser was measured at full power in vacuum to be 1.1 X 10(18) W/cm(2) Although emissions from lower charge states such as Ne6+ and Ne7+ closely follow rates predicted by tunneling theory, emissions from Ne8+ and Ne9+ are observed at irradiances 2 orders of magnitude below tunneling theory estimates. We discuss the origins of these anomalously high charge states and the implications to the development of short-pulse, ultrahigh-brightness x-ray sources. (C) 1996 Optical Society of America