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Järleblad, H., Stagner, L., Salewski, M., Eriksson, J., Nocente, M., Schmidt, B. S. & Larsen, M. R. (2024). A framework for synthetic diagnostics using energetic-particle orbits in tokamaks. Computer Physics Communications, 294, Article ID 108930.
Open this publication in new window or tab >>A framework for synthetic diagnostics using energetic-particle orbits in tokamaks
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2024 (English)In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 294, article id 108930Article in journal (Refereed) Published
Abstract [en]

In fusion plasma physics, the large-scale trajectories of energetic particles in magnetic confinement devices are known as orbits. To effectively and efficiently be able to work with orbits, the Orbit Weight Computational Framework (OWCF) was developed. The OWCF constitutes a set of scripts, functions and applications capable of computing, visualizing and working with quantities related to fast-ion (FI) orbits in toroidally symmetric fusion devices. The current version is highly integrated with the DRESS code, which enables the OWCF to compute and analyze the orbit sensitivity for arbitrary neutron- and gammadiagnostics. However, the framework is modular in the sense that any future codes (e.g. FIDASIM) can be easily integrated. The OWCF can also compute projected velocity spectra for FI orbits, which play a key role in many FI diagnostics. Via interactive applications, the OWCF can function both as a tool for investigative research but also for teaching. The OWCF will be used to analyze and simulate the diagnostic results of current and future fusion experiments such as ITER. The orbit weight functions computed with the OWCF can be used to reconstruct the FI distribution in terms of FI orbits from experimental measurements using tomographic inversion.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Nuclear fusion, Fast ions, Orbits, Weight functions
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-518476 (URN)10.1016/j.cpc.2023.108930 (DOI)001086563600001 ()
Available from: 2023-12-19 Created: 2023-12-19 Last updated: 2023-12-19Bibliographically approved
Rud, M., Moseev, D., Jaulmes, F., Bogar, K., Eriksson, J., Järleblad, H., . . . Salewski, M. (2024). Diagnostic weight functions in constants-of-motion phase-space. Nuclear Fusion, 64(3), Article ID 036007.
Open this publication in new window or tab >>Diagnostic weight functions in constants-of-motion phase-space
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2024 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 64, no 3, article id 036007Article in journal (Refereed) Published
Abstract [en]

The fast-ion phase-space distribution function in axisymmetric tokamak plasmas is completely described by the three constants of motion: energy, magnetic moment and toroidal canonical angular momentum. In this work, the observable regions of constants-of-motion phase-space, given a diagnostic setup, are identified and explained using projected velocities of the fast ions along the diagnostic lines-of-sight as a proxy for several fast-ion diagnostics, such as fast-ion D alpha spectroscopy, collective Thomson scattering, neutron emission spectroscopy and gamma-ray spectroscopy. The observable region in constants-of-motion space is given by a position condition and a velocity condition, and the diagnostic sensitivity is given by a gyro-orbit and a drift-orbit weighting. As a practical example, 3D orbit weight functions quantifying the diagnostic sensitivity to each point in phase-space are computed and investigated for the future COMPASS-Upgrade and MAST-Upgrade tokamaks.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2024
Keywords
weight functions, fast ions, diagnostics, constants-of-motion phase-space
National Category
Fusion, Plasma and Space Physics Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-522980 (URN)10.1088/1741-4326/ad1fac (DOI)001149802700001 ()
Funder
EU, European Research Council, 101052200
Available from: 2024-02-13 Created: 2024-02-13 Last updated: 2024-02-13Bibliographically approved
Järleblad, H., Stagner, L., Eriksson, J., Nocente, M., Kirov, K., Rud, M., . . . Salewski, M. (2024). Fast-ion orbit origin of neutron emission spectroscopy measurements in the JET DT campaign. Nuclear Fusion, 64(2), Article ID 026015.
Open this publication in new window or tab >>Fast-ion orbit origin of neutron emission spectroscopy measurements in the JET DT campaign
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2024 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 64, no 2, article id 026015Article in journal (Refereed) Published
Abstract [en]

In the JET DTE2 deuterium-tritium campaign, neutron diagnostics were employed to measure 14 MeV neutrons originating from D(T,n)4He reactions. In discharge 99965, a diamond matrix detector (KM14) and a magnetic proton recoil (MPRu) detector with a vertical and an oblique line-of-sight were used, respectively. At the timepoints of interest, a significant decrease in the expected diagnostic signals can be observed as electromagnetic wave heating in the ion cyclotron range of frequencies (ICRF) is switched off. Utilizing only TRANSP simulation data, the fast-ion distribution is found to have been likely composed mostly of trapped orbits. In contrast, analysis performed using orbit weight functions revealed that the majority of neutrons in the KM14  MeV and MPRu  cm measurement bins are to have originated from fast deuterium ions on co-passing orbits. This work explains the perhaps surprising results and shows that the relative signal decrease as ICRF heating is switched off is largest for counter-passing orbits. Finally, for the magnetic equilibria of interest, it is shown how stagnation orbits, corresponding to % of the fast-ion distribution, were completely unobservable by the KM14 diagnostic.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2024
Keywords
fast ion, orbit, diagnostics, dt, neutron emission spectroscopy, sensitivity, weight function
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-521854 (URN)10.1088/1741-4326/ad1a57 (DOI)001141948700001 ()
Available from: 2024-01-29 Created: 2024-01-29 Last updated: 2024-01-29Bibliographically approved
Kirov, K. K., Challis, C. D., De la Luna, E., Eriksson, J., Gallart, D., Garcia, J., . . . Van Eester, D. (2024). Impact of interaction between RF waves and fast NBI ions on the fusion performance in JET DTE2 campaign. Nuclear Fusion, 64(1), Article ID 016026.
Open this publication in new window or tab >>Impact of interaction between RF waves and fast NBI ions on the fusion performance in JET DTE2 campaign
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2024 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 64, no 1, article id 016026Article in journal (Refereed) Published
Abstract [en]

This work presents a study of the interaction between radio frequency (RF) waves used for ion cyclotron resonance heating and the fast deuterium (D) and tritium (T) neutral Beam injected (NBI) ions in DT plasma. The focus is on the effects of this interaction, also referred to as synergistic effects, on the fusion performance in the recent JET DTE2 campaign. Experimental data from dedicated pulses at 3.43 T/2.3 MA heated at (i) 51.4 MHz, giving the central minority H and n = 2 D, and at (ii) 32.2 MHz for the central minority 3He and n = 2 T. Resonances are analysed and conclusions are drawn and supported by modelling of the synergistic effects. Modelling with transport code TRANSP runs with and without the RF kick operator predict a moderate increase, of about 10%, in DT rates for the case of the RF wave-fast D NBI ion interactions at the n = 2 harmonic of ion cyclotron resonance, and a negligible impact due to synergistic interaction between fast T NBI ions and RF waves. JETTO modelling gives a 29% enhancement in fusion rates due to the interction between RF waves and fast D NBI ions, and an 18% enhancement in fast T NBI ions. Analysis of experimental neutron rates compared to TRANSP predictions without synergistic effects and magnetic proton recoil neutron spectrometer indicate an enhancement of approximately 25%-28% in fusion rates due to RF interaction with fast D ions, and an enhancement of approximately 5%-8% when RF waves and fast T NBI ions are interacting. The contributions of various heating and fast ion sources are assessed and discussed.

Place, publisher, year, edition, pages
IOP Publishing Ltd, 2024
Keywords
RF waves, fast ions, DT plasma, JET, fusion performance
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-522771 (URN)10.1088/1741-4326/ad0dd5 (DOI)001113353900001 ()
Available from: 2024-02-12 Created: 2024-02-12 Last updated: 2024-02-12Bibliographically approved
Rigamonti, D., Dal Molin, A., Muraro, A., Rebai, M., Giacomelli, L., Gorini, G., . . . Tardocchi, M. (2024). The single crystal diamond-based diagnostic suite of the JET tokamak for 14 MeV neutron counting and spectroscopy measurements in DT plasmas. Nuclear Fusion, 64(1), Article ID 016016.
Open this publication in new window or tab >>The single crystal diamond-based diagnostic suite of the JET tokamak for 14 MeV neutron counting and spectroscopy measurements in DT plasmas
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2024 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 64, no 1, article id 016016Article in journal (Refereed) Published
Abstract [en]

The Joint European Torus (JET) has recently conducted its second deuterium-tritium (DT) experimental campaign DTE2, providing unique opportunity for studying both physics and engineering aspects of nuclear fusion plasmas. This also allowed the exploitation of new diagnostics and technologies that were not available during the first JET DT campaign held in 1997. Among these new instruments, the enhancement projects of the JET nuclear diagnostics lead to the development and installation of synthetic single crystal diamond detectors along different collimated line of sights. This paper describes the single crystal diamond-based diagnostic suite of the JET tokamak and the enhanced 14 MeV neutron diagnostic capabilities in terms of neutron yield and high resolution neutron spectroscopy. The diamond characterization measurements and the calibration procedure at JET are shown, together with performance of the diamond based neutron spectrometer as 14 MeV neutron yield monitor which allows the separation of 2.5 MeV and 14 MeV neutrons in trace tritium plasmas. The first high-resolution 14 MeV neutron spectroscopy measurements in neutral beam injection-heated DT plasmas are presented, allowing thermal and non-thermal neutron component separation. Prospects for the diagnose of DT burning plasmas such as ITER and SPARC will be presented.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2024
Keywords
nuclear diagnostics, neutron spectroscopy, single crystal diamond detectors, tokamaks, nuclear fusion diagnostics
National Category
Fusion, Plasma and Space Physics Subatomic Physics Accelerator Physics and Instrumentation Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-518112 (URN)10.1088/1741-4326/ad0a49 (DOI)001107217900001 ()
Available from: 2023-12-21 Created: 2023-12-21 Last updated: 2023-12-21Bibliographically approved
Schmidt, B. S., Salewski, M., Moseev, D., Baquero-Ruiz, M., Hansen, P. C., Eriksson, J., . . . Äkäslompolo, S. (2023). 4D and 5D phase-space tomography using slowing-down physics regularization. Nuclear Fusion, 63(7), Article ID 076016.
Open this publication in new window or tab >>4D and 5D phase-space tomography using slowing-down physics regularization
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2023 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 63, no 7, article id 076016Article in journal (Refereed) Published
Abstract [en]

We compute reconstructions of 4D and 5D fast-ion phase-space distribution functions in fusion plasmas from synthetic projections of these functions. The fast-ion phase-space distribution functions originating from neutral beam injection (NBI) at TCV and Wendelstein 7-X (W7-X) at full, half, and one-third injection energies can be distinguished and particle densities of each component inferred based on 20 synthetic spectra of projected velocities at TCV and 680 at W7-X. Further, we demonstrate that an expansion into a basis of slowing-down distribution functions is equivalent to regularization using slowing-down physics as prior information. Using this technique in a Tikhonov formulation, we infer the particle density fractions for each NBI energy for each NBI beam from synthetic measurements, resulting in six unknowns at TCV and 24 unknowns at W7-X. Additionally, we show that installing 40 LOS in each of 17 ports at W7-X, providing full beam coverage and almost full angle coverage, produces the highest quality reconstructions.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2023
Keywords
fast ions, tomography, slowing-down, NBI, Tokamak, stellarator
National Category
Fusion, Plasma and Space Physics Condensed Matter Physics Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-506581 (URN)10.1088/1741-4326/acd6a6 (DOI)000997174200001 ()
Available from: 2023-06-28 Created: 2023-06-28 Last updated: 2023-06-28Bibliographically approved
Mantsinen, M. J., Jacquet, P., Lerche, E., Gallart, D., Kirov, K., Mantica, P., . . . Tardocchi, M. (2023). Experiments in high-performance JET plasmas in preparation of second harmonic ICRF heating of tritium in ITER. Nuclear Fusion, 63(11), Article ID 112015.
Open this publication in new window or tab >>Experiments in high-performance JET plasmas in preparation of second harmonic ICRF heating of tritium in ITER
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2023 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 63, no 11, article id 112015Article in journal (Refereed) Published
Abstract [en]

The reference ion cyclotron resonance frequency (ICRF) heating schemes for ITER deuterium-tritium (D-T) plasmas at the full magnetic field of 5.3 T are second harmonic heating of T and 3He minority heating. The wave-particle resonance location for these schemes coincide and are central at a wave frequency of 53 MHz at 5.3 T. Experiments have been carried out in the second major D-T campaign (DTE2) at JET, and in its prior D campaigns, to integrate these ICRF scenarios in JET high-performance plasmas and to compare their performance with the commonly used hydrogen (H) minority heating. In 50:50 D:T plasmas, up to 35% and 5% larger fusion power and diamagnetic energy content, respectively, were obtained with second harmonic heating of T as compared to H minority heating at comparable total input powers and gas injection rates. The core ion temperature was up to 30% and 20% higher with second harmonic T and 3He minority heating, respectively, with respect to H minority heating. These are favourable results for the use of these scenarios in ITER and future fusion reactors. According to modelling, adding ICRF heating to neutral beam injection using D and T beams resulted in a 10%-20% increase of on-axis bulk ion heating in the D-T plasmas due to its localisation in the plasma core. Central power deposition was confirmed with the break-in-slope and fast Fourier transform analysis of ion and electron temperature in response to ICRF modulation. The tail temperature of fast ICRF-accelerated tritons, their enhancement of the fusion yield and time behaviour as measured by an upgraded magnetic proton recoil spectrometer and neutral particle analyser were found in agreement with theoretical predictions. No losses of ICRF-accelerated ions were observed by fast ion detectors, which was as expected given the high plasma density of n e approximate to 7-8 x 1019 m-3 in the main heating phase that limited the formation of ICRF-accelerated fast ion tails. 3He was introduced in the machine by 3He gas injection, and the 3He concentration was measured by a high-resolution optical penning gauge in the sub-divertor region. The DTE2 experiments with 3He minority heating were carried with a low 3He concentration in the range of 2%-4% given the fact that the highest neutron rates with 3He minority heating in D plasmas were obtained at low 3He concentrations of similar to 2%, which also coincided with the highest plasma diamagnetic energy content. In addition to 3He introduced by 3He gas injection, an intrinsic concentration of 3He of the order of 0.2%-0.4% was measured in D-T plasmas before 3He was introduced in the device, which is attributed to the radioactive decay of tritium to 3He. According to modelling, even such low intrinsic concentrations of 3He lead to significant changes in ICRF power partitioning during second harmonic heating of T due to absorption of up to 30% of the wave power by 3He.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2023
Keywords
ICRF heating, fast ions, computational modelling, JET tokamak, H-mode hybrid plasma scenario, deuterium-tritium fuel mixture
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-515604 (URN)10.1088/1741-4326/aceb08 (DOI)001083183500001 ()
Available from: 2023-11-08 Created: 2023-11-08 Last updated: 2023-11-08Bibliographically approved
Maslov, M., Lerche, E., Auriemma, F., Belli, E., Bourdelle, C., Challis, C. D., . . . Van Eester, D. (2023). JET D-T scenario with optimized non-thermal fusion. Nuclear Fusion, 63(11), Article ID 112002.
Open this publication in new window or tab >>JET D-T scenario with optimized non-thermal fusion
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2023 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 63, no 11, article id 112002Article in journal (Refereed) Published
Abstract [en]

In JET deuterium-tritium (D-T) plasmas, the fusion power is produced through thermonuclear reactions and reactions between thermal ions and fast particles generated by neutral beam injection (NBI) heating or accelerated by electromagnetic wave heating in the ion cyclotron range of frequencies (ICRFs). To complement the experiments with 50/50 D/T mixtures maximizing thermonuclear reactivity, a scenario with dominant non-thermal reactivity has been developed and successfully demonstrated during the second JET deuterium-tritium campaign DTE2, as it was predicted to generate the highest fusion power in JET with a Be/W wall. It was performed in a 15/85 D/T mixture with pure D-NBI heating combined with ICRF heating at the fundamental deuterium resonance. In steady plasma conditions, a record 59 MJ of fusion energy has been achieved in a single pulse, of which 50.5 MJ were produced in a 5 s time window (P fus = 10.1 MW) with average Q = 0.33, confirming predictive modelling in preparation of the experiment. The highest fusion power in these experiments, P fus = 12.5 MW with average Q = 0.38, was achieved over a shorter 2 s time window, with the period of sustainment limited by high-Z impurity accumulation. This scenario provides unique data for the validation of physics-based models used to predict D-T fusion power.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2023
Keywords
tokamak, nuclear fusion, tritium
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-516064 (URN)10.1088/1741-4326/ace2d8 (DOI)001083547400001 ()
Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2023-12-18Bibliographically approved
Hobirk, J., Challis, C. D., Kappatou, A., Lerche, E., Keeling, D., King, D., . . . Zerbini, M. (2023). The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium. Nuclear Fusion, 63(11), Article ID 112001.
Open this publication in new window or tab >>The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium
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2023 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 63, no 11, article id 112001Article in journal (Refereed) Published
Abstract [en]

The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with the ITER-like Be/W wall. The development started in pure Deuterium with refinement of the plasma current, and toroidal magnetic field choices and succeeded in solving the heat load challenges arising from 37 MW of injected power in the ITER like wall environment, keeping the radiation in the edge and core controlled, avoiding MHD instabilities and reaching high neutron rates. The Deuterium hybrid plasmas have been re-run in Tritium and methods have been found to keep the radiation controlled but not at high fusion performance probably due to time constraints. For the first time this scenario has been run in Deuterium-Tritium (50:50). These plasmas were re-optimised to have a radiation-stable H-mode entry phase, good impurity control through edge Ti gradient screening and optimised performance with fusion power exceeding 10 MW for longer than three alpha particle slow down times, 8.3 MW averaged over 5 s and fusion energy of 45.8 MJ.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2023
Keywords
magnetic fusion, hybrid scenario, Tritium, D-T, isotope effects
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-520771 (URN)10.1088/1741-4326/acde8d (DOI)001088283400001 ()
Available from: 2024-01-17 Created: 2024-01-17 Last updated: 2024-01-17Bibliographically approved
Hobirk, J., Challis, C. D., Kappatou, A., Lerche, E., Keeling, D., King, D., . . . Zerbini, M. (2023). The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium. Nuclear Fusion, 63(11), Article ID 112001.
Open this publication in new window or tab >>The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium
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2023 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 63, no 11, article id 112001Article in journal (Refereed) Published
Abstract [en]

The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with the ITER-like Be/W wall. The development started in pure Deuterium with refinement of the plasma current, and toroidal magnetic field choices and succeeded in solving the heat load challenges arising from 37 MW of injected power in the ITER like wall environment, keeping the radiation in the edge and core controlled, avoiding MHD instabilities and reaching high neutron rates. The Deuterium hybrid plasmas have been re-run in Tritium and methods have been found to keep the radiation controlled but not at high fusion performance probably due to time constraints. For the first time this scenario has been run in Deuterium-Tritium (50:50). These plasmas were re-optimised to have a radiation-stable H-mode entry phase, good impurity control through edge Ti gradient screening and optimised performance with fusion power exceeding 10 MW for longer than three alpha particle slow down times, 8.3 MW averaged over 5 s and fusion energy of 45.8 MJ.

Place, publisher, year, edition, pages
IOP Publishing Ltd, 2023
Keywords
magnetic fusion, hybrid scenario, Tritium, D-T, isotope effects
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-516223 (URN)10.1088/1741-4326/acde8d (DOI)001088283400001 ()
Available from: 2024-01-25 Created: 2024-01-25 Last updated: 2024-01-25Bibliographically approved
Projects
Fundamental physics studies of the heating and confinement of energetic particles in fusion reactor conditions with neutron diagnostics at JET and MAST-U [2021-05485_VR]; Uppsala University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0892-3358

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