Recommended data on proton-ion collision rate coefficients for Fe X–Fe XXIII ions

Abstract

Aims. Proton-ion collisions are important for excitation or de-excitation of certain excited states in a high-temperature low density astrophysical plasma. Methods. In the present work an evaluation of data obtained for proton-induced transitions in Fe X-Fe XXIII ions is carried out with the help of different theoretical methods. Results. A simple analytical formula with seven parameters is suggested. This formula allows us to describe the dependence of the proton rate coefficient on the proton temperature in a wide temperature range. The values of the free parameters have been determined by fitting the approximation formula to numerical data and are presented for recommended data together with fitting accuracies. By comparing proton collision rates with electron rates it is shown that proton impact excitation processes may be important for Fe X, XI, XIII-XV, XVII-XXIII ions. The results obtained can be used for plasma kinetics calculations and for the development of spectroscopic methods of astrophysical plasma diagnostics.

Validation of Spectroscopic Model for Fe Ions in Non-Equilibrium Ionization Plasma in LHD and Hinode

“…Energy levels, transition probabilities, and electron-impact excitation and ionization cross sections were calculated with the HULLAC atomic code [27]. Proton-impact rate coefficients were taken from recommended data [15]. For comparison, we also calculated population densities and photon emissivity coefficients using the ADAS package [28].…”

“…As Hinode EIS measures Fe VIII-XXIV lines for plasma diagnostics as good indices for the solar transition region over a wide electron temperature range, we have constructed collisional-radiative (CR) models for Fe 7+ -Fe 23+ ions to analyze both solar and laboratory plasmas [9][10][11][12][13][14]. We have carefully examined atomic data of Fe ions to be used in the CR models [15,16], and so far, have applied the models to the measurements of laboratory plasmas to validate the CR models and atomic data for Fe XIII [9,14], Fe XIV [14], Fe XV [14], Fe XXI [12], and Fe XXII [13].…”