Electron Collision Excitation of the Lower Ar I and Xe I Levels

Transcription

1 Electron Collision Excitation of the Lower Ar I and Xe I Levels Ch. Berenguer 1 K. Katsonis 1 R.E.H. Clark 2 1 Laboratoire de Physique des Gaz et des Plasmas, Université Paris-sud, Orsay, France 2 Nuclear Data Section, International Atomic Energy Agency

2 Electron collision excitation cross sections (σ e ) and the corresponding rate coefficients α ji for various distribution functions have been calculated in a collaborative effort and were used in our Collisional-Radiative (C-R) models. Special care was given to the α ji values because the overall shape of the theoretical spectra obtained by C-R models depends strongly on the accuracies of both transition probabilities and electron collision excitation data.

3 We focus on the special case of electron impact excitation cross sections from the ground 3p (5p) and 4s (6s) shells of the neutral Ar (Xe) to the lowly excited levels of the atom. Calculations of cross sections for excitation from the ground state of argon and from the metastable states of the 4s and 6s configurations of argon and xenon respectively have recently been completed. Calculations have also been carried out for the excitation from the transitory 4s levels of argon. Similar work is underway for xenon.

4 In evaluating these σ e we compare results calculated using the following theoretical methods: I. Distorted Wave (DW) approximation using the Los Alamos ACE codes. II. First Order Many Body Theory (FOMBT), also with the ACE code, especially near the threshold. III. Quasi-classical evaluations following numerical solutions of the few body problem. IV. The semi-empirical formula introduced by H.W. Drawin, as adapted by K. Katsonis for the rare gas atoms.

5 We have carried out calculations I and II using different sets of configurations and compared the resulting cross sections. The comparisons with III and IV which are based on experimental energies and on transition probabilities calculated with the Coulomb approximation and NIST values when available are often very satisfactory in the whole energy range and especially in the near threshold energies which are of interest for fusion applications. Comparisons with the small number of available experimental data have also been made.

6 THESE UNIVERSITE PARIS SUD OPTICAL DIAGNOSTICS OF HIGH ENERGY DENSITY PLASMAS. Chloe BERENGUER Reporters: R.E.H. CLARK M. CORNILLE Examiners: E. BIEMONT C. BOISSE-LAPORTE Director of Thesis: K. KATSONIS Orsay, 2009

7 SUMMARY Evaluation of Atomic Data for Argon and Xenon species 1. e - Collision Cross Sections (σ ι ) Methods of calculation Evaluations 2. Rate Coefficients Applications Conclusions and perspectives

8 Evaluation of Atomic Data for Argon (Xenon) species 1. e - Collision Cross Sections (σ ι ) a. ACE and CTMC Codes / Q-C formulas: excitation, ionizations b. Inverse Processes : de-excitation, recombinations - radiative, - dielectronic, - few body c. Evaluations: Ground Levels (GL)* Metastables Levels* Transitory Levels* d. Photo-ionization / Radiative Recombination * Report LPGP-GA-23 * Reports LPGP-GA-21 ; LPGP-GA-22, * Report LPGP-GA-26

9 Methods for cross section calculation Q-C methods: Q-C formulas introduced by H.W. Drawin following Gryziński Adapted by K. Katsonis for e - collision excitation / ionization of Ar, Xe I CTMC (3,4,5 body) developed par K. Katsonis High energies: Born / Low Energies: Wannier/Rost ab-initio Codes: ACE (Atomic Collision with Electrons) with CATS Excitation: DW, FOMBT Ionization: DW, BE, SH RDW developed by R. Srivastava and collaborators

10 Evaluation of Atomic Data for Argon (Xenon) species 1. e - Collision Cross Sections (σ ι ) a. ACE and CTMC Codes / Q-C formulas: excitation, ionizations b. Inverse Processes : de-excitation, recombinations - radiative, - dielectronic, - few body c. Evaluations: Ground Levels (GL)* Metastable Levels* Transitory Levels* d. Photo-ionization / Radiative Recombination * Report LPGP-GA-23 * Reports LPGP-GA-21 ; LPGP-GA-22, * Report LPGP-GA-26

11 Εvaluations: GAPHYOR Reports / Contributions 1. K. Katsonis, Ch. Berenguer, Excitation of the Xe I 6s Metastables to the 6p and 7p Configurations, report LPGP-GA-21, Orsay, France (2008). 2. K. Katsonis, Ch. Berenguer, Ar I Transition Probabilities and Excitation Cross Sections Involving the 4s Metastable Levels and the 4/5p Configurations, report LPGP-GA-22, Orsay, France (2008). 3. K. Katsonis, Ch. Berenguer, Electron Collision Excitation of the Lower Ar I Levels, report LPGP-GA-23, Orsay, France (2008). 4. K. Katsonis, Ch. Berenguer, Ar I Transition Probabilities and Excitation Cross Sections from the 4s Transitory Levels to the 4/5p Configurations, report LPGP-GA-26, Orsay, France (2009). K. Katsonis, Ch. Berenguer, R.E.H. Clark, 4s 4p Electron Collision Excitation of the Ar I, ICPEAC XXVI, July 2009, Kalamazoo (USA)

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14 Report LPGP-GA-21 Orsay, April 2008 Excitation of the Xe I 6s Metastables to the 6p and 7p Configurations Konstantinos Katsonis, Chloe Berenguer

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17 Report LPGP-GA-22 Orsay, April 2008 Ar I Transition Probabilities and Excitation Cross Sections Involving the 4s Metastable Levels and the 4/5p Configurations Konstantinos Katsonis, Chloe Berenguer

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21 Report LPGP-GA-23 Orsay, December 2008 Electron Collision Excitation of the Lower Ar I Levels Konstantinos Katsonis, Chloe Berenguer

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25 Report LPGP-GA-26 Orsay, March 2009 Ar I Transition Probabilities and Excitation Cross Sections from the 4s Transitory Levels to the 4/5p Configurations Konstantinos Katsonis, Chloe Berenguer

26 Evaluation of Atomic Data for Argon (Xenon) species 2. Rates of Collisional Processes Integration / Parametrization codes: INTEG08: Integration of cross sections coming from different calculations / evaluations (choice of distribution function, temperature span, adapted parametrization) PARAM08: Parametrization of the calculated/integrated rate coefficients + POLY08: Avoid diverging terms in polynomials Exemple of Ar I excitation rates * * M.A. Lieberman, A.J. Lichtenberg, Principles of Plasma Discharges and Materials Processing, 2nd ed., Wiley Interscience, Hoboken, NJ: Wiley, 2005.

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28 Excitation Rate

29 Excitation Rate

30 Excitation Rate

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32 Applications 3. UV BEAM-FOIL SPECTRA of Xe IPNAS (Liège): Xenon ions in UV/VUV region Beams of 300, 700, 1000, 1400, 1700 kev Van de Graaf accelerator nm: 5p 6s,5d,7s,6d Xe II, Xe III-IV, Xe V 7s, 6d: more calculations and experiments needed 300 kev: n e =10 12 cm -3, T e =25 kk

33 4. SPECTRA OF PLASMA REACTOR DIVA

34 5. SPECTRA OF STELLARATOR WEGA IPPG (Greifswald) Argon / Xenon 72 / 19 cm Preview according to coronal model Identification with ID08 Ar / Xe diagnostics

35 CONCLUSIONS Big number of atomic data needed: structure, transition probabilities, excitation cross sections, for numerous species present (Ar, Xe, and ions) Measurements / Calculations / Evaluations

36 PERSPECTIVES More data evaluations Other elements (Kr, In, Cs, W etc) Completion of work for more ionized species