Investigation of fluorescence radiation following radiative recombination of ions and elect.pdfVIP

a r X i v : p h y s i c s / 0 5 0 4 1 0 4 v 1 [ p h y s i c s .a t o m - p h ] 1 5 A p r 2 0 0 5 INVESTIGATION OF FLUORESCENCE RADIATION FOLLOWING RADIATIVE RECOMBINATION OF IONS AND ELECTRONS A. Kupliauskiene?1 Vilnius University Institute of Theoretical Physics and Astronomy A.Gos?tauto 12, LT-01108 Vilnius, Lithuania Abstract A general expression for the double differential cross section of fluorescence radiation fol- lowing photorecombination (PRF) of polarized electrons and polarized ions is derived by using usual atomic theory methods and is represented in the form of multiple expansions over spherical tensors. The ways of the application of the general expression suitable for the specific experi- mental conditions are outlined by deriving the asymmetry parameter of angular distribution of PRF radiation in the case of nonpolarized ions and electrons. This parameter is calculated for neon-like ions and bare nuclei. A very strong dependence of the asymmetry parameter of PRF radiation angular distribution on free electron energy is obtained. PACS: 34.80.Lx; 32.50.+d; 33.20.Rm Keywords: Electron-ion recombination; Fluorescence; High-Z ion 1. Introduction Radiative recombination (RR) is one of the dominant processes leading to the decrease of ionization degree of highly charged ions in laboratory and astrophysical plasmas. In tokamak [1] and ion storage rings [2] the self alignment of recombined ions arises due to the directed move- ment of ions that determines a strong polarization and asymmetry of the angular distribution of fluorescence radiation. The capture of an electron by an ion can take place in two ways, i.e. photorecombination (PR) and dielectronic recombination (DR). In PR, an ion A with charge n+ captures a free electron, and the excess of the energy is emitted as PR radiation (PRR): e?(pms) +A n+(α1J1M1) → A(n?1)+(α2J2M2) + hν(??1k01). (1) 1Corresponding author. Tel.: +37052612723. E-mail address: akupl@itpa.lt (A. Kupliauskiene?). 1 Here p is