The Ar(17+) Ly(alpha 2)/Ly(alpha 1) ratio in Alcator C-Mod tokamak plasmas

• High-quality spectra of hydrogen-like Ar(17+) have been obtained from Alcator C-Mod tokamak plasmas using a spatially imaging high-resolution x-ray spectrometer system in an extensive study of the underlying high-n satellite lines. The ratio of Ly(alpha 2) (1S(1/2)-2P(1/2)) to Ly(alpha 1) (1S(1/2)-2P(3/2)) was found to be similar to 0.52 regardless of plasma parameters, which is somewhat greater than the ratio of the statistical weights of the upper n = 2 levels, 0.5. This difference is mainly due to the effects of collisional excitation of fine-structure sub-levels. For the observations presented here, electron densities were in an extended range from 3 x 10(19) to 4 x 10(20) m(-3) with electron and ion temperatures between 1 and 4 keV. Experimental results are compared to calculations from COLRAD, a collisional-radiative modelling code, and good agreement is shown.

Ämnesord

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Nyckelord

hydrogen-like ions

ti-xxii

precision-measurement

intensity ratios

fine-structure

atomic levels

one-electron

lamb shift

temperature

transitions

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)