L. Piehl

M. Kimura

S. "Zou

T." Kato

National Institute for Fusion Science (NIFS-Repository)

...101Energy (keV/amu)• Hoeksba et a/. (1989)(E)• HoeksbastaJ. (1991)(E)A Cine st a/. (1965)(E)X Erma et aI. (1987)(T)i---prnsent0.01-1--c.......,..-..---.-.-............ ......0.110i8 0.1<5lE-510 100corlSion energy (KeViamu)• Shah etat. (1968)1 -present1j' 0.10.01.sli lE-3lE-CFig. 1. Total ionization cross sections re-sulting from a He2++H(ls) collision.Fig. 1. Charge transfer cross sections ofHe2++H(ls)-+He+(n = 2)+H+ at lowen-ergies.[1] S. Zou, 1. PichI, M. Kimura and T. Kato, Phys.Rev. A. 66,042707(2002).[2] M.B. Shah, and D. S. Elliot, P. McCallin, andH. B. Gilbody, J. Phys. B. 21, 2455(1988).range radial coupling enhance the total ionizationcross sections by factors of 4 through 6 in most theenergies considered above. Hence, it appears thatthe "ladder-climbing" process is the most importantionization mechanism in He2+ +H(ls) collisions.ReferencesThe one-electron HeH2+ system is a prototype forinvestigating heteronuclear collision systems, forwhich a numerous works have been done on boththeoretical and experimental sides. Yet, most ofthese works are focus on exciation/capture pro-cess, ionization is left to be understand and remainsa challenge. Accurate ionization cross sections ofHe2++H and/or He++H+ collision systems, how-ever, are essential important for plasma diagnosticsin fusion devices.To address the issue of ionization, we haveemployed the close-coupling method with HeH2+molecular states as basis and electron translation-factor corrections based on molecular-state switch-ing functions, to compute the total and differentialionization cross sections for (a) He2+ +H(ls) and for(b) He+(ls)+H+ collision systems at projectile ener-gies 1-20 keY/amu. Basis sets with up to 20 boundstates and 12 partial waves at 32 energies for contin-uum states have been used, and good convergenceof results as a function of basis size is found. Weshould emphasize that the exact wavefunctions ofphysical continuums are employed in the presentcalculation without any discretization. The num-ber of continuum state energies mentioned above isthe number of interpolation knots for integration.It should be not confused with pseudostate expan-sion. This approach has been successfully appliedto study ionization processes in low-energy proton-hydrogen collisions [1].The results are compared with recent theoret-ical calculations and available experimental values[2]. Good agreement is found with recent exper-imental measurements. Total ionization and state-selected charge transfer cross sections resulting froma He2++H(ls) collision are plotted in Fig. 1 and 2as part of the preliminary results.We find the degeneracy of 3da- and 2pa- at R -+00 plays an important role in the ionization ofH(ls)by He2+. The 2pa- -+ 3da- excitation caused by long§ 8. Molecular Orbital Study Ionizationin Low-Energy He2++H(1 s) ANDHe+(l s)+H+ CollisionsZou, S. (Grad. Univ. Adv.),Piehl, L. (Aizu Univ.),Kimura, M. (Yamaguchi Univ.),Kato, T.376

Molecular Orbital Study Ionization in Low-Energy He2++H(1 s) and He+(l s)+H+ Collisions

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