X-ray spectroscopy of highly charged Ni-like and neighboring ions of Bi, Nd and Pr

The electron beam ion trap (EBIT) at the National Institute of Standards and Technology (NIST) was used to confine and probe Bi, Nd and Pr ions at different electron beam energies and densities near their Ni-like ionization potentials. Time resolved spectra were recorded by a transition edge sensor (TES) x-ray microcalorimeter array of detectors [1]. The non-Maxwellian plasma was modeled by collisional-radiative calculations to reliably predict the spectral emission of the ion cloud [2].

Aided by these collisional-radiative calculations, the analysis of the spectra has led to the identification of several new transitions in the Ni-like isoelectronic sequence, along with new lines in the Cu-like and Zn-like sequence. These identifications include forbidden magnetic octupole (M3) and electric quadrupole (E2) transitions, which can greatly affect plasma conditions [3]. By using the quantum defect formula, we identified a series of high n Rydberg transitions converging towards the ionization limit for the Ni-like ions.

References

[1] P. Szypryt, G. C. O’Neil, E. Takacs, et al. Rev. Sci. Instrum. 90 (2019) 23107

[2] Y. Ralchenko and Y. Maron, J. Quant. Spec. and Rad. Trans. 71 (2001) 609

[3] T. Burke , E. Takacs, Dipti, A. Hosier, et. al. Eur. Phys. J. D (2024) 78