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

Journal Article · Tue Oct 07 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4896497· OSTI ID:22305737

Garcia-Lechuga, M. ^[1]; Fuentes, L. M. ^[2]; Grützmacher, K.; Rosa, M. I. de la ^[1]

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1. Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, 47011-Valladolid (Spain)
2. Departamento de Física Aplicada, Universidad de Valladolid, 47011-Valladolid (Spain)

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.

• OSTI ID: 22305737
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 13; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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