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Data for Atomic Processes Related to Neutral Beams in Fusion Plasma
Closed for proposals
Project Type
Project Code
F43023CRP
2110Approved Date
Status
Start Date
Expected End Date
Completed Date
26 May 2023Participating Countries
Description
Neutral beam injection is a standard method to heat the plasma in fusion experiments and it is intended to be used for power control in ITER and perhaps in a reactor. Neutral beams also have important diagnostic uses, both via photoemission from the beam neutrals due to interaction with the plasma and via photoemission from plasma impurities after interaction with the beam. Modelling of the beam penetration into the plasma and of the spectroscopic signals relies on detailed data for atomic processes that involve the neutral beam particles. In spite of the importance of the data there are quite significant gaps, especially related to processes starting from an excited state of the neutral atom. On the other hand, for processes starting from the ground state of the neutral atom there are often several different families of calculated or measured data, obtained using different approximations or experimental methods, and it is important to assess their uncertainties and to recommend best data. The CRP on data for atomic processes of neutral beams in fusion plasma is intended to provide evaluated and recommended data for the principal atomic processes relevant to heating and diagnostic neutral beams in fusion plasmas.
Objectives
To support fusion energy research in Member States by providing trusted data for atomic processes relevant to neutral beam heating and neutral beam-based diagnostics of fusion plasma, and thereby to contribute to the development of fusion energy generation.
Specific objectives
Assess the sensitivity of predictions of charge transfer impurity spectra (CXRS or CHERS) in fusion plasma to uncertainties in atomic data.
Develop, assemble, evaluate and recommend state-resolved cross sections and (where needed) density matrix elements for excitation, ionization and charge transfer in collisions between hydrogen (H, D, T) neutrals and protons or deuterons at collision energy of the neutrals from about 1 keV to 1 MeV.
Based on uncertainties in the evaluated atomic data, assess associated uncertainties in representative simulations and predictions of beam penetration, beam photoemission and charge transfer spectra in fusion plasma conditions.
Assess the sensitivity of predictions of hydrogen beam penetration and of beam emissions (BES and MSE) in relevant fusion plasma conditions to uncertainties in atomic data.
If possible, develop recommendations for state-resolved cross sections for collisions between hydrogen neutrals and the most relevant partially stripped impurities (elements Ar, Fe, Kr and W) at hydrogen energy from about 1 keV to 1 MeV.
To the extent that it matches other work in the CRP, develop and evaluate data for high energy collision processes in the hydrogen beam neutralizer and for atomic processes of neutral beams of helium and lithium in fusion plasma.
Assemble, evaluate and recommend state-resolved cross sections and (where needed for fusion applications) density matrix elements for excitation and ionization in collisions between electrons and hydrogen neutrals at electron energy from about 100 eV to 100 keV.
Develop, assemble, evaluate and recommend state-resolved cross sections for excitation, ionization and charge transfer in collisions between hydrogen (H, D, T) neutrals and the principal fully stripped impurity ions (elements He, Be, C, N, O; other light elements and Ne, Ar, Kr with lower priority) at hydrogen energy from about 1 keV to 1 MeV.
Impact
This CRP has produced more extensive and more accurate cross section data for the modelling of Neutral Beams in fusion energy devices; in particular, a revised recommendation for the proton-impact ionization of hydrogen has been made that indicated an increased value of this cross section by about 50% at energies relevant to the fuelling of tokamak plasmas. A code-comparison exercise involving eight different computational techniques provided valuable information about the validity of these techniques in different energy regions for the important processes of electron capture, ionization and excitation relevant to neutral beam modelling. 10 different Neutral Beam modelling codes were benchmarked against different plasma scenarios and the consequences of differences, particularly with respect to beam emission, were analyzed in detail.
Relevance
Neutral beam injection is a standard method to heat the plasma in fusion experiments and it is intended to be used for power control in ITER and perhaps in a reactor. Neutral beams also have important diagnostic uses, both via photoemission from the beam neutrals due to interaction with the plasma and via photoemission from plasma impurities after interaction with the beam. Modelling of the beam penetration into the plasma and of the spectroscopic signals relies on detailed data for atomic processes that involve the neutral beam particles – this CRP has evaluated and recommended data for such processes and augmented the IAEA's relevant databases for the benefit of Member States engaged in fusion energy research.