Scaling behavior of radiative recombination cross sections and rate coefficients

Charge-state selective recombination rate coefficients were measured by time of flight (TOF) analyzed highly charged Si ions extracted from an electron-beam ion trap. Additionally, the combination of simultaneous TOF and x-ray measurements and a separation of the dielectronic recombination contribution in the x-ray spectra is used for extracting electron-impact excitation rate coefficients for several overlaying charge states. Experimentally derived dielectronic recombination spectra for XIII and XIV Si are compared and found in excellent agreement with the results of relativistic many-body perturbation theory calculations.

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“…RR can be very well calculated for all charge states using Refs. [26,27]. RR rates for Si ions are also reported by Ref.…”

Section: Resultsmentioning

confidence: 64%

Electron-impact recombination and excitation rates for charge-state-selected highly charged Si ions

et al. 2020

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“…The measured recombination rates of Ar' + are analyzed by fitting a smooth "background" and the convolved DR resonances. In the figure, the dotted line is the calculated RR rate coefficient based on the Kramers cross section corrected by the Gaunt factor [8] and the effective charge [14], using kT~= 20 meV and kTII = 1.5 X 10 eV; the full line shows the fit, which includes the nonresonant RR background and five DR resonances as listed in Table I; however, the fit requires a 60% higher nonresonant contribution than the calculated RR provides. An independent calculation of the RR cross section for this system was found to be only 15% lower than our calculation [15].…”

Section: Observation Of Enhanced Electron-ion Recombination Rates At mentioning

confidence: 99%

Observation of Enhanced Electron-Ion Recombination Rates at Very Low Energies

et al. 1995

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A strong enhancement of electron-ion recombination over expected rates at sub-eV relative energies is revealed for highly charged ions. Measured Ne' + and Ar' + recombination rates were found to be enhanced at low (&1 rneV) energies by factors of 4 and 10 over theoretical predictions of radiative recombination rates, respectively.It is shown that the majority of the enhancement in Ar' is caused by very low lying An = 0 dielectronic recombination resonances; nevertheless, the nonresonant contributions to the measured recombination rates for both systems were found to be significantly higher than predicted by presently available models.PACS numbers: 34.80.Kw, 32.80.HdAmong the fundamental electron-ion interactions which occur in plasmas [1,2], recombination at low energies has turned out to be surprisingly unpredictable.Measurements performed under the most precise conditions yet achieved have consistently yielded experimental rates far above theoretical expectations [3 -6]. No convincing explanation of these enhanced rates exists, nor have detailed quantitative spectra in the sub-meV region been presented.In models describing recombination in electron coolers one considers three basic processes: radiative recombination (RR), where energy and momentum conservation is balanced by the emission of a photon, e + a '-A" "'+ hv, three-body recombination (TBR), where the excess energy is imparted to a neighboring free electron, e +e +A+ A~'~+ e and, for nonbare ions, dielectronic recombination (DR), where a free electron is captured resonantly with the excitation of a bound electron in the ion. This process can be viewed as the time reverse of Auger emission.

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“…However, in the storage ring experiments, deviations from theoretical RR predictions by Kramers have been found for a highly charged ion. Below 10 meV the measured rate coefficient for Ne 10+ is found higher by a factor of 4 as compared to the Kramers calculation [6].…”

Section: Introductionmentioning

confidence: 74%

Electron-ion Recombination at Sub-zero Temperature

Bhattacharyya¹,

Roy²

1999

Acta Phys. Pol. A

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In this paper we have considered two-step radiative recombination channel over the existing spontaneous radiative recombination channel to explain the causes of experimentally obtained enhanced recombination rate at sub-zero temperature. The existing recombination rate due to spontaneous radiative recombination is 4 times smaller than the recent experimental data. In the case of Ne10+ we obtain good agreement between theory and experiment when contribution from two-step radiative recombination channel is added to the spontaneous radiative recombination channel. Recombination rate for Ar es + is calculated. The radiation spectrum given out by two-step radiative recombination and spontaneous radiative recombination in the recombination rate processes are discrete spectrum and continuous spectrum, respectively. Experimental identification of these two channels through the spectral signatures is suggested.

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Scaling behavior of radiative recombination cross sections and rate coefficients

Cited by 40 publications

References 16 publications

Electron-impact recombination and excitation rates for charge-state-selected highly charged Si ions

Electron-impact recombination and excitation rates for charge-state-selected highly charged Si ions

Observation of Enhanced Electron-Ion Recombination Rates at Very Low Energies

Electron-ion Recombination at Sub-zero Temperature

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