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Report on Atomic and Molecular Data for Fusion and Propulsion # § # $ K. Katsonis , M. Cornille , G. Maynard , R.E.H. Clark , J. Abdallah Jr. * # Laboratoire de Physique des Gaz et des Plasmas, UMR 8578, Université Paris-sud 91405 Orsay cedex, FRANCE. § Laboratoire de LUTH, Observatoire de Paris, Meudon, FRANCE $ IAEA Vienna AUSTRIA. * LANL Los Alamos USA. [email protected], tel. 0033169156543, Fax 0033169157844 [email protected] [email protected] [email protected] [email protected] An extensive data collection, production and application effort is in progress in our laboratory (LPGP) especially within the Atomic and Molecular Data for Diagnostics and Modeling research group, which enlarges the scope of a previous LPGP group on Atomic Physics of Fusion Plasmas. This work is developed in collaboration with other specialized laboratories from allover the world. On this new project, emphasis is given to fusion oriented data, but data for electric propulsion, plasma reactors and natural plasmas are also included within the scope. Main processes studied and methods used are: 1. Ionization and excitation of atoms(ions) in collisions of atoms(ions) with atomic, ionic and molecular targets. The n-particle Classical Trajectory Monte Carlo (n-CTMC) method and LCAO method have been used to obtain the corresponding cross sections (see e.g. Refs. 1, 2). 2. Ionization and excitation of atoms(ions) in collisions of electrons with atomic, ionic and molecular targets. The n-CTMC method has also been used to obtain the corresponding cross sections (Ref. 3). 3. Transition probabilities (Aji) of rare gases atoms and ions. Most of the work is based in the Coulomb approximation (CbA) and concerns evaluation of Aji in LS and jK coupling between levels ji having energies experimentally known (Refs. 4, 5). Ab initio quantum methods are implementing the CbA calculations. 4. Recombination (radiative, di-electronic) and simple photo-ionization (Ref. 6). Evaluations are based in quasi-classical approximation and existing formulas (Kramers). Available data on transition probabilities concern the species summarily listed in Table I. Although transition probabilities can be found in numerous databases (notably in the database of NIST) these additional data have been used to develop Collisional-Radiative (C-R) models allowing for the study of rare gas plasmas (Ar, Xe) in experimental devices, industrial applications and natural plasmas. Such models, meant for fusion application, have been often made available in the past (see e.g. Refs 7, 8). Theoretical results obtained by our C-R models are compared with those provided by existing models, whenever they are available. A systematic validation effort is under way, including comparison of our theoretical spectra with those obtained experimentally in various plasmas. In fact, this comparison constitutes a theoretical support to emission spectroscopy, a powerful optical diagnostics tool largely used in studying and monitoring a multitude of industrial, laboratory and natural plasmas. In fact, because these plasmas are rarely in Local Thermodynamic Equilibrium (LTE), a prerequisite of satisfactory plasma electron density n e and temperature Te evaluation by emission spectroscopy is the existence of a detailed (CR) model, taking into account the main physical processes influencing the plasma state and the dynamics of its main constituents (Ref. 9). The theoretical spectra which such a model generates match the experimental ones whenever the experimental values of ne and Te are introduced. In practice, in validating C-R models, discrepancies are observed which often are due to the atomic data included in such models. In generating theoretical spectra pertaining to each atom(ion) multiplet, the most sensible atomic data are the relevant Aji and the electron collision excitation cross sections ij. We note that the latter are actually poorly known, especially for low ionization stages and near the excitation threshold. Although we are working to obtain an improved set of them we now focus on the evaluation of the former, especially of the Aji of the Ar(2, 3)+ ions generating the Ar III, IV spectra and of those of the Xe(2, 3)+ ions, which are evaluated in an analogous way. These Aji have been used to establish C-R models of Ar and Xe plasmas for electric propulsion (Ref. 6) but are also needed for optical diagnostics of the Tokamak plasmas near the wall and in modeling laser-matter interactions. Extensive studies of the Ar III and Xe III spectra exist, but the present status of Aji cannot be considered sufficient for generating the theoretical spectra even of the most prominent visible lines (Ref. 10) coming from the Ar III multiplets 4s 4p, 5p (corresponding to the well known “red” and “blue” lines of Ar I but somehow shifted here) 4p 4d, 5d and 3p 4s, 5s (resonant). The analogous Xe III multiplets (which have principal quantum numbers increased by two) are more dispersed and even more difficult to reproduce theoretically. In accordance with the gap observed in the Grotrian diagrams, the resonant lines which belong to the 3p 4s, 5s multiplets (5p 6s, 7s for Xe III) together with the important metastable levels, give spectra in the UV region. On the other hand, multiplets corresponding to close-lying terms, result in lines located in the infrared region. As for the Ar IV and Xe IV data, these are very badly known. We are actually involved in evaluating AjI data within the frame of a Coordinated Research Program (CRP) of the IAEA. Experimental evaluation of the Aji needed for the considered C-R models is clearly too wide a task, therefore experiments are mostly reserved for benchmark purposes. Consequently, various theoretical methods have been developed, for which in our group we are extensively using the quasi-classical CbA method mentioned in 3., in conjunction with two ab initio quantum codes (Ref. 11): (i) The SUPERSTRUCTURE (SST) package (Ref. 12), developed at University College (UCL) by Eissner and collaborators and based in a non-relativistic Hamiltonian using orbitals calculated in scaled Thomas-Fermi-Dirac-Amaldi (TFDA) potentials and (ii) An extension of the H-F RCG Mod 4 program of Cowan given in the LANL site (http://aphysics2.lanl.gov/tempweb/, also Ref. 13). The methods in (i) and (ii) are extensively used in laboratories with which we collaborate in data base development. The Aji obtained in the CbA approximation whenever experimental values are used for the energy levels are very satisfactory, but of course restricted only to transitions allowed in the coupling scheme chosen, that is often LS or jK. The ab initio methods are able to evaluate also forbidden Aji which become allowed in the context of LSJ, a wide scheme of intermediate coupling. And also Aji for transitions for which the wavelengths are unknown. Detailed comparison of the results obtained by CbA, LANL and SST calculations for the 4s 4p multiplet of Ar III will be given elsewhere (Ref. 14). As an example of our work on C-R models validation, we report here on the comparison of the generated theoretical spectra with those obtained for the plasma of a direct current discharge device with carbon cathode, available at the LPIIM Laboratory in Marseille (Ref. 15). First, we generate by our C-R model a set of theoretical spectra, encompassing a sufficiently wide field of n e and Te values for this experiment. Spectra from this set are compared with the experimental spectra which are obtained for the DC discharge plasma, for a discharge current within 40 mA and 70 mA and a pressure varying from 0.4 mbar to 0.6 mbar. Once a theoretical spectrum is found similar with an experimental one, it is leading to the corresponding n e and Te conditions of the plasma. We obtained by this diagnostic method a plasma T e of the order of 11000 –12000 °K, varying according to the pressure and discharge current conditions. Ionic stages included in the model allow for estimations based on the intensities also of the ionic lines; these are compared with those obtained from the atomic lines. A comparison of the experimental and theoretical spectra of part of the “red” prominent multiplet 4s 4p lines of the Ar I spectrum is given in Figs. 1 and 2. The experimental spectrum is from an Ar plasma reactor of coaxial microwave type (RCM) available in our laboratory (see Ref. 16) and the theoretical one from our model. We are looking forward to replace the Ar working gas by Xenon and to add a small admixture of Xe in order to obtain a differential diagnostics of the discharge (Ref. 17) and to further validate our C-R model for Xe plasmas. Such a diagnostics can be directly used in Tokamak plasmas in the presence of rare gases and adapted to other elements. Especially for fusion related data which are of interest in the present meeting, a selection of the elements of interest to fusion (codename Procrustes) has been made by IAEA back in 1980 and regularly revised subsequently. This choice include current constituents of the controlled fusion plasmas, but also impurities and elements as Ge (ECRII heated reverse sheer) Ar and Xe introduced “ad hoc” by gas puffing or laser blow off (LBO) for cooling and/or diagnostics. In order to enlarge and validate accordingly our database we take profit from a considerable number of collaborations which we have developed. We are looking forward to enter the described numerical data in the GAPHYOR database available in our laboratory. Through a connection with the IAEA database which has been previously established (Ref. 18) these will be available also by the IAEA. References 1. Dimitriou K 2001 “Study of ion and electron collisions with atoms and molecules by the CTMC method” PhD Thesis, Université de Paris-sud, Orsay, France, December 2001 2. Dimitriou K, Aymar F, Katsonis K, Winter HP, Chibishov M I, Janev R K, Urbain X anf Brouillard F “Atomic Data for H+ + He (NLM) Collisions: Single Ionization, Excitation and Charge Exchange Cross Sections”, in press. 3. Sattin F and Katsonis K “Electron Impact Ionization Close to the Threshold: Classical Calculations“ J. Phys. B: At. Mol. and Opt. Phys., 36 L63 2003 4. Bates D R and Damgaard A 1949 Phil. Trans. Roy. Soc. (London) A242, 101 5. Katsonis K and Drawin H W 1976 “Transition Probabilities of Ar I” Rept. EURCEA-FC-835, Fontenay-aux-Roses, also Katsonis K. and Drawin H W 1980 JQSRT 23 1 6. Siskos A “Constantes Atomiques et Modèles C-R pour la Propulsion Ionique”, PhD Thesis, Université de Paris-sud, Orsay, France, April 2005 7. Katsonis K. 1976 “Statistical and Kinetic Study of Ar non-LTE Plasmas” Doctorat d’Etat Thesis, EUR-CEA-FC 820, Fontenay-aux-Roses France 8. Griffin D C, Pindzola M S, Show J A, Badnell N R, O’Mullane M and Summers H P “Electron-impact excitation and ionisation of Ar+ for the determination of impurity influx in tokamaks” 1997 J. Phys. B 30 3543 9. Katsonis K, Dzierzega K and Pellerin S HTMP 7 559 2003 10. Katsonis K, Clark R E H, Cornille M, Siskos A, Ndiayé A and J. Abdallah Jr. 2005 “Rare Gases Transition Probabilities for Plasma Diagnostics” Plasma Conference Opole 2005, Opole, Poland 11. Katsonis K, Clark R E H, Cornille M, Abdallah Jr J, Siskos A and Ndiayé A 2005 “Quasi-classical versus quantum evaluation of transition probabilities: The Ar III 4s 4p case” in prep. 12. Eissner W, Jones M and Nussbaumer H 1974 Compt. Phys.Commun. 8, 270 13. Cowan R D 1981 “The Theory of Atomic Structure and Spectra” Univ. of California Press, Berkeley Ca 14. Katsonis K, Clark R E H, Cornille M, and Abdallah J Jr. XXIV ICPEAC, Rosario, 2005 15. Katsonis K, Dominique C, Arnas C, Cornille M and Siskos A 2005 “Emission Spectroscopy of a DC Discharge with Carbon Cathode” Plasma Conference Opole 2005, Opole, Poland 16. Katsonis K, Boisse-Laporte C, Bonnet J, Letout S. and Siskos A 2004 “C-R Modeling and Spectroscopic Diagnostics of SPT Plasmas” 4th ISPC, 2-9 June, Sardenia, Italy 17. Malyshev M V and Donnelly V M, Phys. Rev. E 60 6016 1999 18. Humbert D, Ralchenko Y, Clark R E H, Katsonis K, “GENIE and DANSE: Two atomic and molecular data web search engines for fusion and plasma physics” Proc. 30th European Physical Society Conference on Controlled Fusion and Plasma Physics, 7-11 July 2003, St Petersburg, Russia Table I Ar III 123456789101112131415- 3p 4s 4p 5s 4s 4p 3d 4p 3p 3d 3d 4f 3d 5f 4d 4f 4d 5f 4p 4d 3p 4d 3p 5s 5s 5p 3d 5p 4d 5p Xe III 12345678910111213141516171819- 5p 6s 6p 7s 6s 6p 5d 6p 5p 5d 5d 6f 5d 7f 6d 6f 6d 7f 6p 6d 5p 6d 5p 7s 7s 7p 5d 7p 6d 7p 5d 4f 5d 5f 6d 4f 6d 5f Forbidden 6s 4f 7s 4f 7s 5f Ar II 12345678- 3p 4s 4p 5s 4s 4p 3d 4p 3p 3d 3d 4f 3d 5f 4d 4f Xe II 12345678- 5p 6s 6p 7s 6s 6p 5d 6p 5p 5d 5d 6f 5d 7f 6d 6f 9101112131415- 4d 5f 4p 4d 3p 4d 3p 5s 5s 5p 3d 5p 4d 5p 910111213141516171819- 6d 7f 6p 6d 5p 6d 5p 7s 7s 7p 5d 7p 6d 7p 5d 4f 5d 5f 6d 4f 6d 5f Forbidden 6s 4f 7s 4f 7s 5f Ar I 123456789101112131415- 3p 4s 4p 5s 4s 4p 3d 4p 3p 3d 3d 4f 3d 5f 4d 4f 4d 5f 4p 4d 3p 4d 3p 5s 5s 5p 3d 5p 4d 5p Xe I 12345678910111213141516171819- 5p 6s 6p 7s 6s 6p 5d 6p 5p 5d 5d 6f 5d 7f 6d 6f 6d 7f 6p 6d 5p 6d 5p 7s 7s 7p 5d 7p 6d 7p 5d 4f 5d 5f 6d 4f 6d 5f 70000 811.75 30 mTorr - 500 W 800 - 870 nm 50000 40000 805 810 815 820 825 830 835 840 845 850 867.03 I 852.38 826.68 10000 0 800 841.05 810.59 20000 842.70 30000 800.84 801.70 Nbre de Coups / s 60000 Expérience: Argon RCM, Pos. 0 855 860 865 870 (nm) Fig. 1. Experimental spectrum of RCM plasma reactor in the red region [800-870 nm]. 70000 811.754 Intensité [erg cm s ] 60000 -3 -1 Modèle C-R Ar I-III 12 -3 Te = 11 kK ; ne = 5x10 cm 2 =6.24x10 50000 40000 0 800 805 810 815 820 825 830 835 840 845 (nm) Fig. 2. Theoretical spectrum in the region of Fig. 1 [800-870 nm]. 850 855 867.033 I 852.378 841.052 826.679 800.836 801.699 10000 810.592 Minces Aij LS 20000 842.694 30000 860 865 870
