Measurement of effective dielectronic recombination rates for Fe ix, x, and xi

Effective rate coefficients for dielectronic recombination of Fe-ix, -x, and -xi ions at electron densities in the range of 3 ×{} 10¹⁶ cm^-3 and electron temperatures up to 220 eV, were deduced from the time histories of emission lines in a small θ-pinch plasma. The iron impurity in the hydrogen plasma was introduced by a laser puffing method. The intensities of lines from these ionization stages were measured as functions of time and interpreted by means of a time-dependent corona ionization-recombination model. A one-dimensional computer code, which takes into account the radial variations of Tₑ and nₑ, was used for the simulation of time histories. The effective rate coefficients were found to be equal to or smaller than currently accepted theoretical values for low-density plasmas.