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Title: OPTIMIZATION OF A SOLAR SIMULATOR FOR PLANETARY-PHOTOCHEMICAL STUDIES

Low-temperature microwave-powered plasma based on hydrogen and hydrogen with noble gas mixtures are widely used as a continuous vacuum ultraviolet (VUV) source in laboratory experiments carried out to mimic the photochemistry in astrophysical environments. In this work, we present a study dedicated to optimizing such sources in terms of mono-chromaticity at Lyα (H(Lyα) line at 121.6 nm ∼ 10.2 eV) and high spectral irradiance. We report the influence on the emission spectrum of a wide range of experimental conditions including gas composition (pure H{sub 2}, pure He, and H{sub 2}/He mixture), gas pressure, flow rates, and microwave power. The absolute spectral irradiance delivered by this VUV light source has been measured. With a microwave input power of 100 W, the best conditions for producing a quasi-monochromatic source are a 1% H{sub 2}/He gas mixture at a total pressure of 5 mbar and a flow rate of 2 sccm. By changing the microwave input power from 30 to 120 W, H(Lyα) increases by more than one order of magnitude. A comparison between the current measurements and the solar VUV spectral irradiance is reported over 115–170 nm.
Authors:
; ; ; ; ;  [1]
  1. Laboratoire Interuniversitaire des Systèmes Atmosphériques, LISA, UMR 7583, CNRS, Université Paris Est Créteil and Université Paris Diderot, Institute Pierre Simon Laplace, 61 Avenue du Général De Gaulle, F-94010 Créteil Cedex (France)
Publication Date:
OSTI Identifier:
22520206
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 218; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; EMISSION SPECTRA; FAR ULTRAVIOLET RADIATION; HELIUM; HYDROGEN; LIGHT SOURCES; LYMAN LINES; MICROWAVE RADIATION; MONOCHROMATIC RADIATION; OPTIMIZATION; PHOTOCHEMISTRY; PLASMA; RADIANT FLUX DENSITY; SOLAR SIMULATORS; SUN