Ionization balance in EBIT and tokamak plasmas

The equilibrium state in tokamak core plasmas has been studied using the re lative intensities of resonance x-ray lines, for example Ly(alpha) (H-like) , "w" (He-like), and "q" (Li-like) from test ions such as Ar+15, Ar+16, and Ar+17. A full spatial analysis involves comparison of the line intensities with ion diffusion calculations, including relevant atomic rates. A zero-d imensional model using a global ion loss rate approximation has also been d emonstrated by comparison with the data collected from a Johann configurati on spectrometer with a charged coupled device (CCD) detector. Since the lin es are nearly monoenergetic, their intensities are independent of the instr ument sensitivity and are directly proportional to the ion abundances. This method has recently been applied to Ar in the Oxford electron beam ion tra p (EBIT) with a beam energy in the range 3-10 keV. Taking into account the cross sections for monoenergetic electron collisions and polarization effec ts, model calculations agree with the observed line ratios at 4.1 keV beam energy. This work will be expanded to provide nomograms of ionization state versus line intensity ratios as a function of EBIT beam energy. (C) 2001 A merican Institute of Physics.