Measuring one-dimensional and two-dimensional impurity density profiles on TEXTOR using combined charge exchange-beam emission spectroscopy and ultrasoft x-ray tomography

Bock, Maarten De; Jakubowska, K.; Hellermann, M. von; Jaspers, R.; Donné, A. J. H.; Shmaenok, L. A.

doi:10.1063/1.1787600

Cited by 7 publications

(3 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Calculation of impurity densities from charge exchange intensity is typically performed using an absolute intensity calibration of the diagnostic and a validated model of the neutral beam attenuation to provide the absolute donor neutral densities at each energy. Alternatively, an approximation for the quantity n Z /n e can be derived from the ratio of the charge exchange line intensity to beam emission intensity at the same location 33 . From this quantity, the impurity concentration n Z / i n i can be calculated if only a single impurity species is dominant in the plasma.…”

Section: Impurity Densitiesmentioning

confidence: 99%

Charge exchange recombination spectroscopy at Wendelstein 7-X

Ford

Vanó

Alonso

et al. 2020

Review of Scientific Instruments

View full text Add to dashboard Cite

The Charge Exchange Recombination Spectroscopy (CXRS) diagnostic has become a routine diagnostic on almost all major high temperature fusion experimental devices. For the optimised stellarator W7-X, a highly flexible and extensive CXRS diagnostic has been built to provide high-resolution local measurements of several important plasma parameters using the recently commissioned neutral beam heating. This paper outlines the design specifics of the W7-X CXRS system and gives examples of the initial results obtained including typical ion temperature profiles for several common heating scenarios, toroidal flow and radial electric field derived from velocity measurements, beam attenuation via beam emission spectra and finally, normalised impurity density profiles under some typical plasma conditions.

show abstract

Section: Impurity Densitiesmentioning

confidence: 99%

Charge exchange recombination spectroscopy at Wendelstein 7-X

Ford

Vanó

Alonso

et al. 2020

Review of Scientific Instruments

View full text Add to dashboard Cite

show abstract

“…This replaces the accumulated error on the beam attenuation along the beam path [9], by a local error in the beam emission rate. Beam emission, when combined with charge exchange recombination spectroscopy (CXRS), also has the potential of reducing the need of an absolute calibration of the CXRS spectra and a calculation of the intersection integral between a line of sight and the NB, to a relative calibration between several spectral bands [8,10,11]. The combination of BES and CXRS is the only feasible method to measure helium ash concentrations with the requested accuracy on ITER where only a small fraction (≈1%) of the diagnostic beam reaches the plasma centre and where calibrations of the tokamak side optics on a regular basis will be impossible [12].…”

Section: Motivationmentioning

confidence: 99%

Consistency of atomic data for the interpretation of beam emission spectra

Delabie

Brix

Giroud

et al. 2010

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

Several Collisional-Radiative (CR) models [1, 2, 3] have been developed to calculate the attenuation and the population of excited states of hydrogen or deuterium beams injected into tokamak plasmas. The datasets generated by these CR models are needed for the modelling of beam ion deposition and (excited) beam densities in current experiments, and the reliability of this data will be crucial to obtain helium ash densities on ITER combining charge exchange and beam emission spectroscopy. Good agreement between the different CR models for the Neutral Beam (NB) is found, if corrections to the fundamental cross sections are taken into account. First the H a and H b beam emission spectra from JET are compared with the expected intensities. Second, the line ratios within the Stark multiplet are compared with the predictions of a sublevel resolved model. The measured intensity of the full multiplet is ≈30% lower than expected on the basis of beam attenuation codes and the updated beam emission rates, but apart from the atomic data this could also be due to the characterization of the NB path and line of sight integration and the absolute calibration of the optics. The modelled n = 3 to n = 4 population agrees very well with the ratio of the measured H a to H b beam emission intensities. Good agreement is found as well between the neutral beam power fractions measured with beam emission in plasma and on the JET Neutral Beam Test Bed. The Stark line ratios and s/p intensity ratio deviate from a statistical distribution, in agreement with the CR model in parabolic states from Marchuk et al. [4]. MOTIVATIONPowerful neutral hydrogen or deuterium beams provide the dominant external heating and momentum input in most large scale tokamak experiments. For the interpretation of neutral beam (NB) heated discharges, detailed knowledge is required about the energy distribution of the neutrals (power fractions) and the attenuation of the beams in order to obtain radial proles of the fast ion deposition and hence of the heating, torque and beam driven current. For the quantitative interpretation of Charge eXchange (CX) spectra, the local NB fluxes and population of excited states in the beam are needed to convert CX emissivities into local impurity densities. All these calculations strongly rely on the accuracy of the atomic data for the NB that is provided by Collisional-Radiative (CR) models of the beam [1, 2, 3, 5, 6].When the Beam Emission Spectrum (BES) was recorded for the first time, it was immediately proposed to monitor the beam attenuation, and hence the accuracy of the effective beam stopping cross sections, by using the observed beam emission intensities [7, 8]. This replaces the accumulated error on the beam attenuation along the beam path [9], by a local error in the beam emission rate. Beam emission, when combined with Charge eXchange Recombination Spectroscopy (CXRS), also has the potential of reducing the need of an absolute calibration of the CXRS spectra and a calculation of the intersection integral between a lin...

show abstract

“…tomography system on TEXTOR is to measure 2-D profiles of the local emission coefficients of line radiation emitted by impurity ions. 40,41 It uses a tomographic algorithm to reconstruct the local emission from the line-integrated brightness measured by five pinhole cameras. The cameras are placed symmetrically around a poloidal cross section of the torus in order to obtain the best possible tomographic reconstruction.…”

Section: Vb1 Ultra-sxr Tomographymentioning

confidence: 99%

Overview of Core Diagnostics for TEXTOR

Donné

Bock

Classen

et al. 2005

Fusion Science and Technology

Self Cite

View full text Add to dashboard Cite

The diagnostic system of TEXTOR comprises about 50 individual diagnostic devices. Since the start of the Trilateral Euregio Cluster collaboration, part of the emphasis in the experimental program has shifted toward the study of physics processes in the plasma core. To aid these studies several new and advanced core diagnostics have been implemented, whereas a number of other core diagnostics have been upgraded to higher resolution, more channels, and better accuracy. In this paper a brief overview is given of the present set of plasma core diagnostics at TEXTOR.

show abstract

Measuring one-dimensional and two-dimensional impurity density profiles on TEXTOR using combined charge exchange-beam emission spectroscopy and ultrasoft x-ray tomography

Cited by 7 publications

References 9 publications

Charge exchange recombination spectroscopy at Wendelstein 7-X

Charge exchange recombination spectroscopy at Wendelstein 7-X

Consistency of atomic data for the interpretation of beam emission spectra

Overview of Core Diagnostics for TEXTOR

Contact Info

Product

Resources

About