Accurate modeling of benchmark x-ray spectra from highly charged ions of tungsten

Abstract

We present detailed collisional-radiative modeling for a benchmark x-ray spectrum of highly charged tungsten ions in the range between 3 and 10 Å produced in an electron beam ion trap ͑EBIT͒ with a beam energy of 4.08 keV. Remarkably good agreement between calculated and measured spectra was obtained without adjustable parameters, highlighting the well-controlled experimental conditions and the sophistication of the kinetic simulation of the non-Maxwellian tungsten plasma. This agreement permitted the identification of spectral lines from Cu-like W 45+ and Ni-like W 46+ ions, led to the reinterpretation of a previously known line in Ni-like ion as an overlap of electric-quadrupole and magnetic-octupole lines, and revealed subtle features in the x-ray spectrum arising from the dominance of forbidden transitions between excited states. The importance of level population mechanisms specific to the EBIT plasma is discussed as well.

X-ray spectroscopy ofE2andM3transitions in Ni-like W

“…Ralchenko calculated the line positions, line intensities, and density dependences of the lines [13]. Ralchenko et al also observed the unresolved line in the NIST EBIT using a 4-pixel x-ray calorimeter spectrometer [12]. The feature has also been observed in the LLNL SuperEBIT using a 36-pixel x-ray calorimeter array [14].…”

“…Based on calculations, Loch et al [11] and Ralchenko et al [12,13] have suggested that this feature was actually a blend of the M3 and E2 lines. Ralchenko calculated the line positions, line intensities, and density dependences of the lines [13].…”

Electron Impact Excitation and Dielectronic Recombination of Highly Charged Tungsten Ions

“…An overview of the photoionization, electron-impact ionization, as well as electron-ion recombination of low to moderately-charged tungsten ions was reported very recently, together with a critical assessment of the methods and results [14]. Extreme-ultraviolet (EUV) spectra from a variety of tungsten ions have been recorded at the electron beam ion trap and the Axially Symmetric Divertor EXperiment (ASDEX) Upgrade tokamak facilities [15][16][17][18][19][20][21]. The majority of these spectra have been identified and assigned to nf → 3d (n = 4, 5, 6) and 4d → 3p atomic transitions mostly by performing fully-relativistic ab initio calculations [22][23][24][25].…”

Modelling of the soft X-ray tungsten spectra expected to be registered by GEM detection system for WEST

“…The measurements performed on soft X-ray (SXR) radiations originating from the magnetic fusion plasmas are a standard way to obtain valuable information about the transport of particles in the reactor volume, density, and magnetic confi guration [1][2][3][4][5]. Attention focused on tungsten material is associated with the fact that it became a leading candidate for the plasma-facing material in the future International Thermonuclear Experimental Reactor (ITER) and future tokamaks.…”

“…In this paper, the modelling of the soft L, M, and N X-ray spectra structures for tungsten in high--temperature tokamak plasmas has been performed within the framework of collisional-radiative (CR) model using the fl exible atomic code (FAC) package [4,5,9,10] for electron temperatures and densities relevant to WEST tokamak.…”