1. The CHIANTI database Adding Ionization and Recombination to CHIANTI Dr Peter Young CCLRC/Rutherford Appleton Laboratory, UK Dr Ken Dere George Mason University, USA The CHIANTI database

2. Background Tables of ion fractions as a function of temperature are essential for the analysis of electron-ionized plasmas In the past, rates have been re-assessed on timescales of ~5 years and new tables published Previous calculations include –Mazzotta et al. (1998) –Arnaud & Raymond (1992) –Arnaud & Rothenflug (1985) –Shull & Van Steenberg (1982)

3. The CHIANTI database CHIANTI CHIANTI contains atomic data for the calculation of level populations within ions Major updates occur every ≈ 2 years There is no official CHIANTI ion fraction data-set The user can choose any of the standard ion fraction tables

4. The CHIANTI database CHIANTI version 6 v.6 of CHIANTI will provide –ionization rates –recombination rates –ion fractions derived from these rates

5. The CHIANTI database Ionization Ionization rates have been assessed, and new calculations performed for many ions –K.P. Dere (2006, submitted to ApJ) Experimental cross-section data have been fit with a Burgess & Tully (1992) type fitting formula High energy limit given by the Bethe coefficient f – scaling parameter; I – ionization potential; u = E/I; σ – cross-section

6. The CHIANTI database

7. Fitting the rates The ionization rate coefficients are also fit with a Burgess-Tully type scaling The spline fits to these scaled rates will be provided to the CHIANTI user f – scaling parameter; I – ionization potential; t = kT/I; σ – rate coefficient

8. The CHIANTI database Ionization: FAC calculations For many ions where experimental data are incomplete or missing, new data have been calculated The Flexible Atomic Code (FAC) has been used –relativistic distorted wave code similar to that of Zhang & Sampson (1991) Example: Ni XIV

9. The CHIANTI database Radiative Recombination The baseline set of radiative recombination rates are derived from fits embedded in a fortran routine of D.A. Verner Gives rates for all ions of all elements up to zinc These rates are used as the baseline, supplemented by –Badnell (2006) –Wane & Aymar (1987) –Aldrovandi & Pequignot (1974)

10. The CHIANTI database

11. Radiative Recombination Problems Beyond the sodium sequence, most of the data have been obtained by interpolation/extrapolation of the Woods et al. (1981) data-set for the iron ions Comparisons with other data-sets show differences

12. The CHIANTI database Dielectronic recombination Baseline DR rates are taken from Mazzotta et al. (1998) New DR rates for all sequences up to the sodium sequence have been calculated by N.R. Badnell and co-workers Rates for Cu and Zn were not provided by Mazzotta et al. (1998). These are taken from Mazzitelli & Mattioli (ADNDT, 2002)

13. The CHIANTI database

14. Comparison with Nahar data S. Nahar and colleagues have calculated combined RR and DR rates for many ions Significant differences exist for some ions for cases where new Badnell data are available, and also where older data are being used

15. The CHIANTI database Blue curve: Badnell data Red curve: Nahar data

16. The CHIANTI database Blue curve: Mazzotta data Red curve: Nahar data

17. The CHIANTI database New CHIANTI ion balance Carbon ions

18. The CHIANTI database Conclusions Version 6 of CHIANTI should be ready in around 6 months For all ions of all elements up to zinc it will contain –ionization rates –recombination rates –ion fraction curves