The ITER core imaging x-ray spectrometer

Abstract

The core imaging x-ray spectrometer (CIXS) is one of several ITER diagnostic systems planned for measurements of the central ion and electron temperature profiles and of the toroidal and poloidal rotation velocity profiles, T i , T e , v φ , and v θ respectively. The diagnostic is based on precision determinations of the Doppler broadening and centroid shift of the lines of highly ionized heavy impurities using a curved Bragg crystal spectral disperser and imager. In a departure from earlier designs, the CIXS employs a novel imaging geometry utilizing spherically bent crystals operating at a Bragg angle near 45 • , which spatially and spectrally resolves the x-ray emission from the plasma. In addition, the working radiation will be the L-shell emission of highly charged tungsten ions. Particular emphasis is placed on the strong 3d 5/2 → 2p 3/2 electric dipole transition in neon-like tungsten W 64+ . Here we present the conceptual design of the instrument, which may include an x-ray calorimeter, and discuss the spectral features used in future measurements.

Atomic data of tungsten for current and future uses in fusion and plasma science

“…The ion-temperature, T i , and poloidal and toroidal rotation velocity, v ϕ and v θ , profiles of the ITER core plasmas 2 will be measured using the Core Imaging X-ray Spectrometer (CIXS) [15]. The instrument is being designed for 3 Doppler measurements of the L-shell spectra of highly charged tungsten ions.…”

From X-rays to visible photons - What do we learn from the plasma observations?

“…With the larger fusion plasma experiments also observations of emission from high Z elements will become important and this challenging development has already started both experimentally and theoretically, see Fig. 5 [38][39][40][41]. Now the question is posed, how can we meet the requirements of detection of e.g.…”

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

“…This problem is related to the impurities that are released from the divertor walls, that is why it is so highly desirable to fully understand the impact of the plasma impurities and its effects on plasma scenarios. Such contamination could cause radiative collapses and often lead to a disruption, but on the bright side, impurities could also provide alternative diagnostics for plasma parameters [6][7][8][9]. X-ray spectra originating from highly ionized tungsten are extremely complex and demand exhaustive theoretical studies that can be specifi c to a particular tokamak.…”

“…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.…”