Feasibility of non-thermal helium measurements with charge exchange spectroscopy on ITER

Kappatou, A.; Delabie, E.; Jaspers, Rje Roger; Hellermann, M. von

doi:10.1088/0029-5515/52/4/043007

Cited by 16 publications

(17 citation statements)

References 25 publications

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“…Our tomographic and theoretical results contradict the conventional wisdom that at least two CTS or FIDA views would necessarily be required for tomography of fast-ion velocity distribution functions [12,[22][23][24][25][26][27][28][29][30][31][32]. In an idealized situation in fact just one single CTS or FIDA view suffices to compute an accurate tomography.…”

Section: Discussioncontrasting

confidence: 57%

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements

Salewski¹,

Geiger²,

Nielsen³

et al. 2012

Nucl. Fusion

122

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We compute tomographies of 2D fast-ion velocity distribution functions from synthetic collective Thomson scattering (CTS) and fast-ion D α (FIDA) 1D measurements using a new reconstruction prescription. Contradicting conventional wisdom we demonstrate that one single 1D CTS or FIDA view suffices to compute accurate tomographies of arbitrary 2D functions under idealized conditions. Under simulated experimental conditions, single-view tomographies do not resemble the original fast-ion velocity distribution functions but nevertheless show their coarsest features. For CTS or FIDA systems with many simultaneous views on the same measurement volume, the resemblance improves with the number of available views, even if the resolution in each view is varied inversely proportional to the number of views, so that the total number of measurements in all views is the same. With a realistic four-view system, tomographies of a beam ion velocity distribution function at ASDEX Upgrade reproduce the general shape of the function and the location of the maxima at full and half injection energy of the beam ions. By applying our method to real many-view CTS or FIDA measurements, one could determine tomographies of 2D fast-ion velocity distribution functions experimentally.

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Section: Discussioncontrasting

confidence: 57%

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements

Salewski¹,

Geiger²,

Nielsen³

et al. 2012

Nucl. Fusion

122

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“…The attenuation factor ζ is calculated by a line-integration along the beam path, it requires the radial density profiles of electrons and impurity ions as well as ion specific atomic stopping cross-sections ( Figure 3b). The ADAS effective stopping cross-sections for the injected neutral beam include ionization and charge exchange losses induced by electrons and ions [30,39]. For the forward prediction SOS starts from estimates of both the plasma impurity composition, and also their respective radial profiles.…”

Section: Neutral Beam Modelmentioning

confidence: 99%

“…The rapid decay of excitation rate coefficient as (~1/n 3 ) where n is the principal quantum number prevents the appearance of plume in all other impurities except of He (see also PEC values for HI, HeII, and CVI in Figure 2h). Finally, the type of synthetic active spectra simulated by SOS is that of fast-ion-CX-spectra, i.e., slowing-down fusion alpha particles [26][27][28][29][30], fast beam ions [31][32][33][34][35][36] or minority ions accelerated by Ion Cyclotron Resonance Heating (ICRH). In all three examples of FICX (Fast-Ion-CXRS), the range of energies of the fast ions exceeds by far the width of the CX emission rate function which typically peaks around 50 keV/amu, and contributes dominantly to measurable signals for relative collision velocities less than 100 keV/amu.…”

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confidence: 99%

Simulation of Spectra Code (SOS) for ITER Active Beam Spectroscopy

Hellermann

Bock

Marchuk

et al. 2019

Atoms

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The concept and structure of the Simulation of Spectra (SOS) code is described starting with an introduction to the physics background of the project and the development of a simulation tool enabling the modeling of charge-exchange recombination spectroscopy (CXRS) and associated passive background spectra observed in hot fusion plasmas. The generic structure of the code implies its general applicability to any fusion device, the development is indeed based on over two decades of spectroscopic observations and validation of derived plasma data. Four main types of active spectra are addressed in SOS. The first type represents thermal low-Z impurity ions and the associated spectral background. The second type of spectra represent slowing-down high energy ions created from either thermo-nuclear fusion reactions or ions from injected high energy neutral beams. Two other modules are dedicated to CXRS spectra representing bulk plasma ions (H+, D+, or T+) and beam emission spectroscopy (BES) or Motional Stark Effect (MSE) spectrum appearing in the same spectral range. The main part of the paper describes the physics background for the underlying emission processes: active and passive CXRS emission, continuum radiation, edge line emission, halo and plume effect, or finally the charge exchange (CX) cross-section effects on line shapes. The description is summarized by modeling the fast ions emissions, e.g., either of the α particles of the fusion reaction or of the beam ions itself.

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“…Our joint tomography method could also combine the fast-ion charge exchange spectroscopy (FICXS) (that detects light other than D α but is otherwise similar to FIDA) and the CTS diagnostics at the Large Helical Device (LHD) [49,50]. Moreover, joint tomographic inversions could be directly relevant to ITER where the proposed FICXS [51] and the CTS system [52][53][54][55] could be combined even if there is only one CTS view. Measurements from any other fast-ion diagnostic could be included in our joint tomography prescription, if quantitative weight functions describing the measurements such as those for CTS [34] or FIDA [20,56] can be formulated.…”

Section: Introductionmentioning

confidence: 99%

Combination of fast-ion diagnostics in velocity-space tomographies

et al. 2013

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Fast-ion D α (FIDA) and collective Thomson scattering (CTS) diagnostics provide indirect measurements of fastion velocity distribution functions in magnetically confined plasmas. Here we present the first prescription for velocity-space tomographic inversion of CTS and FIDA measurements that can use CTS and FIDA measurements together and that takes uncertainties in such measurements into account. Our prescription is general and could be applied to other diagnostics. We demonstrate tomographic reconstructions of an ASDEX Upgrade beam ion velocity distribution function. First, we compute synthetic measurements from two CTS views and two FIDA views using a TRANSP/NUBEAM simulation, and then we compute joint tomographic inversions in velocity-space from these. The overall shape of the 2D velocity distribution function and the location of the maxima at full and half beam injection energy are well reproduced in velocity-space tomographic inversions, if the noise level in the measurements is below 10%. Our results suggest that 2D fast-ion velocity distribution functions can be directly inferred from fast-ion measurements and their uncertainties, even if the measurements are taken with different diagnostic methods.

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Feasibility of non-thermal helium measurements with charge exchange spectroscopy on ITER

Cited by 16 publications

References 25 publications

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements

Tomography of fast-ion velocity-space distributions from synthetic CTS and FIDA measurements

Simulation of Spectra Code (SOS) for ITER Active Beam Spectroscopy

Combination of fast-ion diagnostics in velocity-space tomographies

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