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Title: Calculation of the spatial resolution in two-photon absorption spectroscopy applied to plasma diagnosis

We report a detailed characterization of the spatial resolution provided by two-photon absorption spectroscopy suited for plasma diagnosis via the 1S-2S transition of atomic hydrogen for optogalvanic detection and laser induced fluorescence (LIF). A precise knowledge of the spatial resolution is crucial for a correct interpretation of measurements, if the plasma parameters to be analysed undergo strong spatial variations. The present study is based on a novel approach which provides a reliable and realistic determination of the spatial resolution. Measured irradiance distribution of laser beam waists in the overlap volume, provided by a high resolution UV camera, are employed to resolve coupled rate equations accounting for two-photon excitation, fluorescence decay and ionization. The resulting three-dimensional yield distributions reveal in detail the spatial resolution for optogalvanic and LIF detection and related saturation due to depletion. Two-photon absorption profiles broader than the Fourier transform-limited laser bandwidth are also incorporated in the calculations. The approach allows an accurate analysis of the spatial resolution present in recent and future measurements.
Authors:
 [1] ;  [2] ;  [3] ; ; ;  [1]
  1. Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, 47011-Valladolid (Spain)
  2. (Spain)
  3. Departamento de Física Aplicada, Universidad de Valladolid, 47011-Valladolid (Spain)
Publication Date:
OSTI Identifier:
22305737
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 13; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ABSORPTION SPECTROSCOPY; ACCOUNTING; CAMERAS; DECAY; DETECTION; DISTRIBUTION; ENERGY-LEVEL TRANSITIONS; EXCITATION; FLUORESCENCE; FOURIER TRANSFORMATION; HYDROGEN; LASER RADIATION; PHOTONS; PLASMA DIAGNOSTICS; RADIANT FLUX DENSITY; SATURATION; SPATIAL RESOLUTION; THREE-DIMENSIONAL CALCULATIONS