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  • Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW
    Lomanowski, B. A. ...
    A parametrised spectral line profile model is formulated to investigate the diagnostic scope for recovering plasma parameters from hydrogenic Balmer and Paschen series spectroscopy in the context of ... JET-ILW divertor plasmas. The separate treatment of Zeeman and Stark contributions in the line model is tested against the PPP-B code which accounts for their combined influence on the spectral line shape. The proposed simplified model does not fully reproduce the Stark-Zeeman features for the - and - transitions, but good agreement is observed in the line width and wing profiles, especially for n->-5. The line model has been applied to infer radial density profiles in the JET-ILW divertor with generally good agreement between the D5\to 2 , 5\to 3 , 6\to 2 , 7\to 2 and 9\to 2 lines for high recycling and detached conditions. In an L-mode detached plasma pulse the Langmuir probe measurements typically underestimated the density by a factor 2%3 and overestimated the electron temperature by a factor of 5%10 compared to spectroscopically derived values. The line model is further used to generate synthetic high-resolution spectra for low-n transitions to assess the potential for parameter recovery using a multi-parametric fitting technique. In cases with 4 parameter fits with a single Maxwellian neutral temperature component the D 4\to 3 line yields the best results with parameter estimates within 10% of the input values. For cases with 9 parameter fits inclusive of a multi-component neutral velocity distribution function the quality of the fits is degraded. Simultaneous fitting of the D 3\to 2 and 4\to 3 profiles improves the fit quality significantly, highlighting the importance of complementary spectroscopic measurements for divertor plasma emission studies.
    Source: Nuclear fusion. - ISSN 0029-5515 (Iss. 12, Vol. 55, 2015, 1230028)
    Type of material - article, component part
    Publish date - 2015
    Language - english
    COBISS.SI-ID - 30183463
    DOI

source: Nuclear fusion. - ISSN 0029-5515 (Iss. 12, Vol. 55, 2015, 1230028)
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