DIELECTRONIC RECOMBINATION OF Na-LIKE S AND Na-LIKE Ar IN THE PRESENCE OF EXTERNAL FIELDS

• Recombination rate coefficients for two astrophysically relevant Na-like ions, S5+ and Ar7+, were derived frommeasurements at the electron cooler device of the CRYRING heavy-ion storage ring. Additionally, the enhancementof dielectronic recombination (DR) by external fields was studied for these ions. Motional electric fields wereinduced over the electron–ion interaction region by tilting the magnetic field that guides the electrons on thetrajectory of the circulating ions. Field ionization at the dipole magnet prevented the detection of ions recombinedinto high Rydberg states. By comparing integrated areas of the recombination spectra over the field-affected range,enhancement factors of up to 1.9 and 2 were observed in the case of S5+ and Ar7+, for the maximum appliedfields of ∼184 V cm−1 and ∼172 V cm−1, respectively. Saturation was not reached and at higher fields even higherenhancements are to be expected. Plasma DR rate coefficients were obtained from the experimental spectra recordedat different field strengths. For the highest applied fields, increasing enhancement of the plasma DR rates was foundwith higher temperatures, reaching up to ∼42% and ∼73% at 106 K, in the case of S5+ and Ar7+, respectively.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

atomic data – atomic processes – magnetic fields – plasmas

Physics

Fysik

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