Spectral simulation of multivalent collisional-radiative model for W25+–W28+ from EBIT to tokamak plasmas

Abstract

Accurate and reliable atomic modeling of tungsten ions holds significance for both spectral data analysis and the investigation of tungsten behavior within fusion plasma. To examine the impact of various atomic processes on spectral lines, a collisional-radiative model (CRM) involving multiple charge states for tungsten ions was performed with level-to-level processes with configuration interaction, including spontaneous emission, electron collisional ionization, collisional (de)excitation, radiative recombination, charge exchange, resonant capture, and autoionization. The evolution of M1 spectral lines of W25+–W28+ in the 330–540 nm range was measured using the SH-HtscEBIT and was successfully replicated by the multivalent CRM. The photon emission coefficients (PECs) associated with these M1 transitions in fusion plasma have also been furnished, revealing their minimal sensitivity to the influence of recombination and ionization processes. The verification of these PECs’ properties holds potential for the forthcoming density diagnosis of tungsten ions in Tokamak. Subsequently, the multivalent CRM was also conducted to explore the impact of dielectronic recombination on extreme ultraviolet spectra. While resonant capture does lead to an augmentation in the population of autoionizing levels, the contribution of dielectronic recombination to spectral lines for W26+ and W27+ within the 2–8 nm range remains relatively insignificant.