CH spectroscopy for carbon chemical erosion analysis in high density low temperature hydrogen plasma

Journal Article · Mon Oct 12 00:00:00 EDT 2009 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.3238295· OSTI ID:21294357

Westerhout, J; Rooij, G J. van ^[1]; Lopes Cardozo, N J ^[1]; Rapp, J ^[1]

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1. FOM Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, P. O. Box 1207, 3430 BE Nieuwegein (Netherlands)

The CH A-X molecular band is measured upon seeding the hydrogen plasma in the linear plasma generator Pilot-PSI [electron temperature T{sub e}=0.1-2.5 eV and electron density n{sub e}=(0.5-5)x10{sup 20} m{sup -3}] with methane. Calculated inverse photon efficiencies for these conditions range from 3 up to >10{sup 6} due to a steeply decreasing electron excitation cross section. The experiments contradict the calculations and show a constant effective inverse photon efficiency of {approx}100 for T{sub e}<1 eV. The discrepancy is explained as the CH A level is populated through dissociative recombination of the molecular ions formed by charge exchange. Collisional de-excitation is observed for n{sub e}>5x10{sup 20} m{sup -3} and 0.1 eV<T{sub e}<1 eV. These results form a framework for in situ carbon erosion measurements in future fusion reactors such as ITER.

• OSTI ID: 21294357
• Journal Information: Applied Physics Letters, Vol. 95, Issue 15; Other Information: DOI: 10.1063/1.3238295; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON
CHARGE EXCHANGE
CHEMICAL BONDS
CROSS SECTIONS
DE-EXCITATION
ELECTRON DENSITY
ELECTRON TEMPERATURE
ELECTRONS
EROSION
HYDROGEN
ION TEMPERATURE
METHANE
MOLECULAR IONS
PHOTONS
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA PRODUCTION
RECOMBINATION
SPECTROSCOPY