| 1. |
- Zohar, Andrej, et al.
(författare)
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Evaluation of cross sections for fast ion reactions with beryllium in helium and hydrogen fusion plasmas
- 2024
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Ingår i: Nuclear Fusion. - : Institute of Physics Publishing (IOPP). - 0029-5515 .- 1741-4326. ; 64:7
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Tidskriftsartikel (refereegranskat)abstract
- To computationally support hydrogen and helium plasma discharges in the early stages of tokamak operation and to support the commissioning of the neutron detectors during these operational phases, creation of a realistic neutron and gamma ray particle source for Monte Carlo simulations will be needed. One of the most important parts of creating the particle source is calculating the reaction rates of the particle-emitting reactions to determine the emission profile in the plasma and the energy spectra of the emitted particles. In this paper the analysis and evaluation of cross sections for important neutron-emitting reactions, namely, 9Be(p,nγ)9B, 9Be(3He,nγ)11C, and charged-particle emission reactions 9Be(p,d)2α and 9Be(p,α)6Li that cause neutron emission in the next step of interactions are presented. The reaction cross sections were evaluated based on experimental measurements and empirical models describing the interaction of two charged particles. Evaluation of the associated uncertainties was also performed. The main goal of the work is to propose the newly evaluated cross sections for inclusion in the FENDL nuclear data library, thus making the cross section available to other researchers studying the above listed reactions.
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| 2. |
- Lengar, Igor, et al.
(författare)
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Characterization of JET neutron field in irradiation locations for DD, DT and TT plasmas
- 2019
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Ingår i: Fusion engineering and design. - : ELSEVIER SCIENCE SA. - 0920-3796 .- 1873-7196. ; 146, s. 1967-1970
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Tidskriftsartikel (refereegranskat)abstract
- The neutron fluxes and spectra were characterized for four locations close to the plasma and related to activation experiments, as the preparation for the upcoming experimental campaigns in JET. The focus was on the study of a variance reduction technique in order to obtain statistically significant results in the parts of the neutron energy spectra, important for irradiation experiments. The DD, DT and TT plasmas were studied with the Monte Carlo hybrid method and the use of the ADVANTG program for generation of weight windows as variance reduction method to accelerate Monte Carlo simulations. The calculations were optimized to obtain low statistical uncertainties for all energy bins in the 640 energy group structure and for all three plasma sources. This included the acceleration of calculations for reaction rates of capture reactions, i.e. in the thermal flux region in irradiation positions on the first wall. Speed-ups due to use of the hybrid method in excess of two orders of magnitude were found with respect to analog calculations despite the vicinity of the plasma source.
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| 3. |
- Zohar, Andrej, et al.
(författare)
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Long Term Neutron Activation in JET DD Operation
- 2021
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Ingår i: ANIMMA2021 - Advancements in nuclear instrumentation measurement methods and their applications. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- In the 2019 C38 Deuterium-Deuterium campaign at JET several different ITER-relevant materials and dosimetry foils were irradiated in a specially designed long-term irradiation station located inside the vacuum vessel with the purpose of testing the activation of ITER materials by fusion neutrons. The samples were exposed to a neutron fluence of 1.9E14 n/cm(2) during JET discharges performed in the experimental campaign over a period of 5 months. Gamma ray spectroscopy measurements were performed on irradiated samples to determine the activation of different long-lived isotopes in the samples. Monte Carlo computational analysis was performed to support the experiment by using the measured neutron yield and irradiation time. In this paper we focus on the computational analysis of the dosimetry foils that are used in order to measure the local neutron energy spectrum and flux. The foils were chosen to cover different neutron energies: thus Yttrium and some of the Nickel and Cobalt reactions were used to determine the Deuterium-Tritium fusion fraction, while Scandium and Iron and some of the Nickel and Cobalt reactions were used for comparison of the computed activity with the experimental measurements. The obtained C/E values show a reasonably good agreement between calculated and measured activity, thus validating the computational methodology and providing the basis for the analysis of the ITER-relevant materials and future experiments performed at JET in the Deuterium-Tritium campaign.
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