Influence of non-local thermodynamic equilibrium and Zeeman effects on magnetic equilibrium reconstruction using spectral motional Stark effect diagnostic

Reimer, R.; Marchuk, O.; Geiger, B.; Carthy, P. J. Mc; Dunne, M.; Hobirk, J.; Wolf, R. C.

doi:10.1063/1.4994889

Cited by 6 publications

(6 citation statements)

References 41 publications

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“…The technique is much advanced and is implemented in many of present fusion devices [47,48]. The challenge for SOS is to provide an adequate and precise prediction tool for the expected MSE spectra including a reliable estimate for the extraction of amplitudes, line-splits and associated error bars [49]. The task was recently solved by replacing the established statistical models with the simulation of populations of neutral beam in pure parabolic states [37].…”

Section: Sos Modeling Of the Bes (Motional Stark Effect) Spectrummentioning

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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Section: Sos Modeling Of the Bes (Motional Stark Effect) Spectrummentioning

confidence: 99%

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

Hellermann

Bock

Marchuk

et al. 2019

Atoms

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“…Collisional atomic data play a fundamental role in investigating the efficiency of plasma heating using NB injection, beam penetration and also in providing diagnostic information on plasma parameters such as impurity concentration [100], plasma rotation and temperature [101] and measurements of the q-profile [102,103]. The latter information is obtained from the photoemission of fast beam atoms but also the impurity ions.…”

Section: Collisional Atomic Data In Neutral Beam Modeling: Penetratio...mentioning

confidence: 99%

Atomic collisional data for neutral beam modeling in fusion plasmas

Hill,

Dipti,

Heinola

et al. 2023

Nucl. Fusion

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The injection of energetic neutral particles into the plasma of magnetic confinement fusion reactors is a widely-accepted method for heating such plasmas; various types of neutral beam are also used for diagnostic purposes. Accurate atomic data are required to properly model beam penetration into the plasma and to interpret photoemission spectra from both the beam particles themselves and from plasma impurities with which they interact. This paper reviews and compares theoretical methods for calculating ionization, excitation and charge exchange cross sections applied to several important processes relevant to neutral hydrogen beams, including H + Be4+ and H + H+. In particular, a new cross section for the proton-impact ionization of H (1s) is recommended which is significantly larger than that previously accepted at fusion-relevant energies. Coefficients for an empirical fit function to this cross section and to that of the first excited states of H are provided and uncertainties estimated. The propagation of uncertainties in this cross section in modeling codes under JET-like conditions has been studied and the newly-recommended values determined to have a significant effect on the predicted beam attenuation. In addition to accurate calculations of collisional atomic data, the use of these data in codes modeling beam penetration and photoemission for fusion-relevant plasma density and temperature profiles is discussed. In particular, the discrepancies in the modelling of impurities are reported.The present paper originates from a Coordinated Research Project (CRP) on the topic of fundamental atomic data for neutral beam modeling that the International Atomic Energy Agency (IAEA) ran from 2017 – 2022; this project brought together 10 research groups in the fields of fusion plasma modeling and collisional cross section calculations. Data calculated during the CRP is summarized in an Appendix and is available online in the IAEA's atomic database, CollisionDB.

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“…γ/ ∼ 0.1 for typical fusion neutral beam injection energies (∼ 100keV). Often this ratio is underestimated creating the impression that the Zeeman effect can always be neglected, however more recent studies have identified circumstances where it cannot be disregarded [12,13]. The parabolic states |n, k, m are the natural solution for the pure Stark effect, where n is the principle quantum number, m is the magnetic quantum number and k = n 1 −n 2 , with parabolic quantum numbers n 1 ≥ 0 and n 2 ≥ 0 such that n 1 + n 2 + 1 = n − |m|.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Anisotropic excitation mechanisms may therefore have the potential to preferentially excite one degenerate state over the other, an effect that is not considered in Ref. [13] where parabolic state populations are used for |n, k,m L like states. In our coordinate system the neutral beam atom velocity lies in the xyplane when the electric field is purely motional.…”

Section: Relative Upper-state Populationsmentioning

confidence: 99%

Polarisation of the Balmer-α emission in crossed electric and magnetic fields

Thorman¹

2018

Journal of Quantitative Spectroscopy and Radiative Transfer

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Influence of non-local thermodynamic equilibrium and Zeeman effects on magnetic equilibrium reconstruction using spectral motional Stark effect diagnostic

Cited by 6 publications

References 41 publications

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

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

Atomic collisional data for neutral beam modeling in fusion plasmas

Polarisation of the Balmer-α emission in crossed electric and magnetic fields

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