L-shell x-ray emission from neonlike W64+

Abstract

We present high-resolution crystal spectroscopy measurements of the n = 3 → n = 2 L-shell x-ray transitions of neonlike W 64+ , which include seven electric dipole allowed transitions, two electric quadrupole transitions, and one magnetic quadrupole transition. The resulting wavelength data are compared to recent calculational results, allowing us to clearly distinguish between different theoretical approaches, which need to take into account not only substantial electron correlations effects but also radiative contributions, which in case of the transition from upper level (1s 2 2s 1/2 2p 6 3p 3/2) J=1 to the closed-shell neonlike ground state exceeds 20 eV. Best agreement is found with calculations utilizing the relativistic multi-reference Møller-Plesset approach. In addition to the emission from W 64+ , we have observed several innershell collisional satellite lines associated with oxygenlike W 66+ , fluorinelike W 65+ , sodiumlike W 63+ , and magnesiumlike W 62+ , which provide benchmarks for future calculations as well as for recent calculations using the relativistic many-body perturbation theory. The present measurements also provide accurate rest wavelengths for establishing the instrumental dispersion needed for future measurements of the core plasma motion in the ITER tokamak and show that the candidate W 64+ line for such measurements remains well isolated from neighboring collisional satellite lines even when broadened by the expected, high temperatures in this device.

Extreme Ultraviolet Spectra of Few-Times Ionized Tungsten for Divertor Plasma Diagnostics

“…Detailed laboratory measurements on tungsten ions are well suited for electron beam ion traps (EBITs), where charge-state selection is good and the ion temperature and electron density low. Several studies of tungsten in various ionization stages and spectral ranges have been conducted using EBITs; see, e.g., [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Although designed to have a very wide electron-beam energy range, EBITs have mostly been used at energies above several hundred electron volts, leading to a focus on highly or moderately charged ions with little attention on the first few charge states.…”

Quasirelativistic calculation of 4s24p5, 4s24p44d and 4s4p6configuration spectroscopic parameters for the W39+ion

“…Over the last few years, several experimental works (see, e.g. [6][7][8][9] and the references therein) on the tungsten ions are published. Alongside there is a considerable interest in multicharged ions from theoreticians.…”

Fully Relativistic Electron Impact Excitation Cross-Section and Polarization for Tungsten Ions

“…Beiersdorfer et al [21] reported high-resolution crystal spectroscopy measurements and identified ten lines in neon-like W 64+ arising due to the n = 3→n = 2 L-shell X-ray transitions as electron to the n = 3 level was considered. In case of the O-like W 66+ ion, a number of transitions between levels with n = 2 and n = 3 were investigated.…”

“…X-ray spectroscopy utilizing emissions from L-shell as well as M-shell tungsten ions is an attractive option for tokomak plasma diagnostics [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The temperature of the ITER core will be sufficiently high to produce the L-shell tungsten ionic charged states.…”

“…In this context, we have performed fully relativistic distorted wave (RDW) calculations to obtain cross-sections for various M-and L-shell transitions due to electron impact excitation of highly charged tungsten ions W n+ where n varies from 44 to 66. This work is undertaken in the light of recent measurements in an electron beam ion trap at the Lawrence Livermore National Laboratory reported by Beiersdorfer and his co-workers [19][20][21][22] in which they identified a number of intense lines in the L-and M-shell spectra of various tungsten ions. The electron excitation processes corresponding to these lines are studied in detail due to the importance of the cross-section data to identify and interpret the spectroscopic data of the tungsten ions.…”