The effective ionization and recombination rate coefficients for Fexvi–Fe xxii were obtained by studying the modulation of line emissions by sawtooth oscillations in the TEXT tokamak. Experimental data are matched with the simulation of iron ion emission by a one-dimensional code. The rate coefficients were determined for $T_e$∼350–900 eV and $N_e$∼(4–5.6)×${10}^{13}$ ${\mathrm{cm}}^{\mathrm{-}3}$. The rate coefficients for Fe xvi, xvii, and xviii have large uncertainty partly due to uncertainty of the temperature profile at large radii of the plasma and partly due to other possible atomic processes. The error of ionization rates for Fe xix–Fe xxii is estimated to be less than 40%, while the estimated accuracy of the recombination rates is better than a factor of 2.

• Received 19 January 1988

DOI:https://doi.org/10.1103/PhysRevA.38.4761