E. Szymańska

Modeling of the L and M x-ray line structures for tungsten in high-temperature tokamak plasmas

We present the results of modeling of the L and M x-ray line structures for tungsten in high-temperature plasmas predicted with temperatures relevant to large tokamaks including the Joint European Tokamak and the future International Thermonuclear Experimental Reactor. The simulations have been performed using the Flexible Atomic Code within the framework of the collisional–radiative (CR) model. For L x-ray lines, our results predicted for various levels of CR model sophistication have been compared with the spectrum measured using the electron beam ion trap (EBIT) calorimeter spectrometer at the Livermore SuperEBIT that constitutes a rigorous atomic benchmark for tokamak plasmas. In the case of M x-ray lines, we have reproduced the experimental SuperEBIT spectra as a superposition of theoretical contributions for different ions. The obtained results enable us to propose an approach allowing the decomposition of registered experimental tungsten spectra produced in tokamaks into the theoretically predicted contributions, corresponding to different degrees of ionization.

Influence of multiple outer-shell electron stripping on the Kα and Kβ x-ray energies of iridium

We present theoretical predictions for iridium Kα1,2, Kβ1,3 and Kβ2 energy shifts as a function of outer-shell stripping, evaluated using the multiconfiguration Dirac–Fock method including Breit interaction and QED corrections. The energy shifts are consistent with the K-lines emitted by the plasma made in the plasma-filled rod pinch, and potentially relevant to diagnostics of high-energy density laser-produced plasmas as studied in connection with the National Ignition Facility.

Diagnostics of plasma based on K, L and M x-ray line positions

Ionization can affect the energy of characteristic x-ray lines sufficiently for a single line to be of value in plasma diagnostics. Recently, the ionization of a hot, dense tungsten plasma was determined from a detailed analysis of a single, highly resolved L x-ray line, and in an iridium plasma the change in energy of a single K x-ray line confirmed the theoretical estimate of the ionization. Diagnosing plasmas by these ionization energy shifts depends essentially on computations that can now be performed with sufficient accuracy, e.g. with the multi-configuration Dirac?Fock method. Besides extending earlier computations on the influence of outer-shell ionization on the energy of tungstens K and L x-ray lines, this paper also presents the effect of ionization on the lower-energy M x-ray lines and a discussion of their relative merits for plasma diagnostics.

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

Abstract In the future International Thermonuclear Experimental Reactor (ITER), the interaction between the plasma and the tungsten chosen as the plasma-facing wall material imposes that the hot central plasma loses energy by X-ray emission from tungsten ions. On the other hand, the registered X-ray spectra provide alternative diagnostics of the plasma itself. Highly ionized tungsten emits extremely complex X-ray spectra that can be understood only after exhaustive theoretical studies. The detailed analyses will be useful for proper interpretation of soft X-ray plasma radiation expected to be registered on ITER-like machines, that is, Tungsten (W) Environment in Steady-state Tokamak (WEST). The simulations of the soft X-ray spectra structures for tungsten ions have been performed using the flexible atomic code (FAC) package within the framework of collisional-radiative (CR) model approach for electron temperatures and densities relevant to WEST tokamak.

Modeling of the M X-ray line structures for tungsten and L X-ray line structures for molybdenum

Modeled within the Collisional-Radiative approach, for parameters relevant to plasmas in the centre of JET, the M X-ray line structures for tungsten and L X-ray line structures for molybdenum both occur in the wave length range 5.0-5.35 A; and, their strengths are comparable. Therefore, the spectra obtained with the upgraded high-resolution X-ray spectrometer KX1 on JET should include both tungsten and molybdenum in their interpretation. The same will be true for the high-resolution X- ray diagnostic on tokamaks such as WEST and ITER, where tungsten plasma-facing components will be implemented.

Diagnostics of the plasma parameters based on the K X-ray line positions for various 4d and 4f metals

Abstract This paper shows the theoretical predictions of the outer-shell ionization effect on the positions of Kα1,2, Kβ1,3, and K β2 X-ray lines for some 4d-transition metals (molybdenum and palladium) and 4f rare-earth elements (dysprosium and ytterbium). The ionization energy shifts have been evaluated using the multiconfiguration Dirac-Fock method, containing Breit interaction and quantum electrodynamic (QED) corrections. The presented results are important for obtaining the information about some parameters of plasma generated by different sources, especially by pulsed power machine and short-pulse lasers.