Dissociative Recombination of diatomic cations with electrons in cold plasma

1. Dissociative Recombination of diatomic cations with electrons in cold plasma TSR Francois Olivier WAFFEU TAMO Republic of CAMEROUN Thesis in alternance (2004 - present) Ousmanou MOTAPON University of Douala, CEPAMOQ CAMEROUN Ioan F. SCHNEIDER University of Havre, LMPG FRANCE Workshop on Atomic and Molecular Data for fusion Trieste 2006

2. Variation of electronic density, ne ωplasma ~ (ne)1/2 Reflexion of wave if ωwave < ωplasma neutrals in excited states Emission of light Rich Chemistry Many applications DR is an important process in cold plasma !!! e- + AB+A + B*

3. Direct process Direct capture in a Dissociative state (Doubled excited state) AB** Indirect process Temporary capture in a Rydberg state (Mono-excited state) AB* Resonances !!! Mechanismse- + AB+ ??? A + B*

4. AB+ AB* AB** Quasi-diabatic Representationof relevant molecular states A + B+ A + B*

5. Input AB+ (Ni+,vi+,…) AB* @ quantum defect μ AB** @ Final states of atoms, (N,…) Electronic couplings (BO) Incident electron, l(0,2) Output, σNi+,vi+,N (v) Observable Keep in mind Each rovibrational level N+,v+ of target ion can be viewed as the limit of a series of rovibrational levels of Rydberg states. For a given Ni+ , │Ni+ - l│≤ N ≤│ Ni+ + l │ and N is also coupled to N+ given by: │N- l│≤ N+ ≤│ N+ l │ Multichannel Quantum Defect Theory calculations (I) Rates coefficients α = <σv> Peak Assignments !!!

6. Multichannel Quantum Defect Theory calculations (II) • Procedure for a given initial state of ion σ Ni+,vi+(v)= ∑NσNi+,vi+,N (v) α Ni+,vi+(Ed)= < σ Ni+,vi+.v> averaged Boltzmann rate coefficients α obs ≡ ∑ α Ni+,vi+,(Ed) . Pi • General Assumptions • Maxwell anisotropic distribution for velocity of the electrons , f • Boltzmann distribution, Pi of ions are on the lower rovibra- tionnal states Local rates

7. ANISOTROPIC Maxwell distribution function, f M. Larsson, Int. J. Mass Spectrom. Ion Processes 149/150, 403 (1995) • m, electron mass • v, center-of-mass velocity • vd , detuning velocity at the center of velocity distribution • k, the boltzmann constant • Te, electronic temperature ( experimental conditions)

8. MQDT vsExperimentsHD+ / HD (vi+= 0 &Ni+ =0,...,12) Interpretation of the resonance structure

9. σ.v & α (N=1,3) lin scale • Ni+=1 • l = 0 (s wave) N=1 • l = 2 (d wave) N=1,3 N=1,3 • N=1 N+=1,3 • N=3 N+= 1,3,5 σ.v & α (N=1,3) log scale σ.v ( N=3) bars ≡ predicted resonances Ed(res) = E(ryd) - E(Ni+,vi+) Approximation !!! E(ryd)= E(N+,v+) – Ryd*[2(n-μl)2]-1 σ.v ( N=1)

11. MQDT vsExperimentsHD+ / HD (vi+= 0 &Ni+ =0,...,12) Interpretation of the resonance structure About to be published

12. Boundary of the fusion plasma • M. C. Stroe, M. Fifirig, F. O. Waffeu Tamo, O.Motapon, O. Crumeyrolle, G. Varin-Bréant, A. Bultel, P. Vervisch, A. Suzor-Weiner et I. F. Schneider, “Reactive collisions between electrons and molecular hydrogen cation isotopomers: cross sections and rate coefficients for HD+ and DT+,accepted in APID 13.

13. Direct process ! Rotationnal effects neglected Indirect process & Rotationnal effects Boundary of the fusion plasma (I)HD+ / HD

14. Direct process ! Rotationnal effects neglected Indirect process & Rotationnal effects Boundary of the fusion plasma (II)DT+/DT

15. Direct process ! Rotationnal effects neglected Indirect process & Rotationnal effects Boundary of the fusion plasma (III)HD+ / HD & DT+/DT thin ≡HD+/HD bold ≡ DT+/DT

16. Boundary of the fusion plasma (IV)HD+ / HD(DR,EC, SEC & IC)

17. Thanks for Your attention !SpecialThanks to Organizers & Lecturers !