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Title: Stability of liquid-nitrogen-jet laser-plasma targets

Microscopic jets of cryogenic substances such as liquid nitrogen are important regenerative high-density targets for high-repetition rate, high-brightness laser-plasma soft x-ray sources. When operated in vacuum such liquid jets exhibit several non-classical instabilities that negatively influence the x-ray source's spatial and temporal stability, yield, and brightness, parameters that all are important for applications such as water-window microscopy. In the present paper, we investigate liquid-nitrogen jets with a flash-illumination imaging system that allows for a quantitative stability analysis with high spatial and temporal resolution. Direct and indirect consequences of evaporation are identified as the key reasons for the observed instabilities. Operating the jets in an approximately 100 mbar ambient atmosphere counteracts the effects of evaporation and produces highly stable liquid nitrogen jets. For operation in vacuum, which is necessary for the laser plasmas, we improve the stability by introducing an external radiative heating element. The method significantly extends the distance from the nozzle that can be used for liquid-jet laser plasmas, which is of importance for high-average-power applications. Finally, we show that laser-plasma operation with the heating-element-stabilized jet shows improved short-term and long-term temporal stability in its water-window x-ray emission.
Authors:
; ; ;  [1]
  1. Biomedical and X-Ray Physics, Department of Applied Physics, KTH Royal Institute of Technology/Albanova, 10691 Stockholm (Sweden)
Publication Date:
OSTI Identifier:
22492893
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; BRIGHTNESS; DENSITY; EVAPORATION; HEATING; INSTABILITY; LASER TARGETS; LASER-PRODUCED PLASMA; LIQUIDS; MICROSCOPY; NITROGEN; NOZZLES; OPERATION; SOFT X RADIATION; STABILITY; TIME RESOLUTION; X-RAY SOURCES; YIELDS