Experimental determination of S/XB values of W I visible lines

Journal Article · Tue Dec 15 04:00:00 EST 2009 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3270108· OSTI ID:21371245

Nishijima, D; Doerner, R P; Baldwin, M J ^[1]; Pospieszczyk, A; Kreter, A ^[2]

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1. Center for Energy Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States)
2. Institute for Energy Research-Plasma Physics, Forschungszentrum Juelich, Association EURATOM-FZJ, 52425 Juelich (Germany)

The dependence of the number of ionization events per photon, or so called S/XB value, on the electron temperature, T{sub e}, for W I lines at lambda=400.8, 429.4, 498.2, and 505.3 nm has been experimentally determined by measuring the line emission of W atoms sputtered by Ar plasma bombardment in the PISCES-B linear divertor plasma simulator [R. P. Doerner et al., Phys. Scr. T 111, 75 (2004)]. The measured S/XB values at T{sub e}>10 eV are found to agree with theoretical calculations at an effective temperature T{sub W}=0.1-0.3 eV, which is treated as a free parameter and affects the population of ground states of W atoms. However, compared with previously reported experimental values of S/XB for the 400.8 nm line, our S/XB values are approx5-10 times higher. At T{sub e}<10 eV, it is seen that the S/XB values increase with decreasing electron density, n{sub e}, even with correction of the geometrical loss flux. This indicates that there is a n{sub e} dependence of S/XB, which is also confirmed by comparison of W I line intensity ratios with calculations. It should be, however, noted that no single value of T{sub W} can explain the measured intensity ratios. This suggests that a more complete collisional-radiative model with more accurate rate coefficients and without using the free parameter T{sub W} is required to reproduce the observed n{sub e} and T{sub e} dependence of S/XB.

• OSTI ID: 21371245
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 16; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ELECTRON DENSITY
ELECTRON TEMPERATURE
ELEMENTS
ENERGY LEVELS
GROUND STATES
IONIZATION
METALS
PLASMA
PLASMA DENSITY
REFRACTORY METALS
TRANSITION ELEMENTS
TUNGSTEN