Logo: to the web site of Uppsala University

uu.sePublications from Uppsala University
Change search
Link to record
Permanent link

Direct link
Alternative names
Publications (10 of 478) Show all publications
Valentini, A., Reman, B. C., Nocente, M., Eriksson, J., Järleblad, H., Moseev, D., . . . Salewski, M. (2025). A model for analytical calculations of synthetic neutron energy spectra from beam-target reactions. Nuclear Fusion, 65(2), Article ID 026001.
Open this publication in new window or tab >>A model for analytical calculations of synthetic neutron energy spectra from beam-target reactions
Show others...
2025 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 65, no 2, article id 026001Article in journal (Refereed) Published
Abstract [en]

We present a fully analytical model for calculating energy spectra of neutrons generated by fusion reactions involving a fast ion, or beam, and a stationary ion, or target, in magnetic fusion plasmas. For neutrons moving along the line-of-sight of a detector, the neutron spectrum is given by an analytical expression and the usual differential cross section. This makes the model several orders of magnitude faster than ordinary Monte Carlo simulations and free of any related statistical noise. Additionally, the analytical description of the reaction physics provides much more insight into the formation of the spectrum. An example of this is the bias of beam-target spectra towards high-energy neutron counts, which corresponds to forward-emission events. On the other hand, the fast-ion uniform gyro-angle distribution has an opposite effect, but is ultimately weaker than the preferential forward emission of neutrons. The model is validated against numerical calculations from the forward model code GENESIS to verify its validity and it is furthermore derived from a probabilistic viewpoint, adding further insight.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2025
Keywords
fast ions, nuclear reactions, neutron emission spectroscopy
National Category
Fusion, Plasma and Space Physics Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-546531 (URN)10.1088/1741-4326/ad9bc8 (DOI)001379847900001 ()
Funder
EU, European Research Council, 101052200
Available from: 2025-01-10 Created: 2025-01-10 Last updated: 2025-01-10Bibliographically approved
Valentini, A., Reman, B. C., Nocente, M., Eriksson, J., Järleblad, H., Moseev, D., . . . Salewski, M. (2025). An analytical model for two-step reaction gamma-ray spectroscopy in magnetized plasmas. Nuclear Fusion, 65(4), Article ID 046031.
Open this publication in new window or tab >>An analytical model for two-step reaction gamma-ray spectroscopy in magnetized plasmas
Show others...
2025 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 65, no 4, article id 046031Article in journal (Refereed) Published
Abstract [en]

We present a method to analytically compute gamma-ray spectra generated via two-step fusion reactions, where a gamma-ray is emitted from the excited nucleus generated in the first step of the reaction. If one reactant is energetic and the other is at rest, the first step of the reaction can be treated analytically. The second step, which is the gamma-ray emission from the excited nucleus, can always be treated analytically. The model we derive is tested against the established forward-model code GENESIS, obtaining very satisfactory results. Our fully analytic treatment is a far less expensive technique than standard Monte Carlo methods, achieving several times faster computations. Fast calculations of spectra are especially beneficial when working with finely-resolved 3D-4D phase spaces. Furthermore, tractable analytical expressions give insight that is not provided by Monte Carlo methods. The formalism used for the first step of the reaction additionally allows the computation of birth distributions of fusion products from any beam-target reaction with one reactant at rest, e.g. fusion-born alpha distributions.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2025
Keywords
fast ions, gamma-ray spectroscopy, fusion products, energy distribution, analytical model
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-554687 (URN)10.1088/1741-4326/adc1df (DOI)001454789500001 ()2-s2.0-105001339724 (Scopus ID)
Available from: 2025-04-16 Created: 2025-04-16 Last updated: 2025-04-16Bibliographically approved
Rud, M., Eriksson, L. G., Eriksson, J., Hansen, P. C., Hyvarinen, O., Jarleblad, H., . . . Salewski, M. (2025). Fast-ion phase-space tomography with wave-particle interactions in the ion cyclotron frequency range as prior. Nuclear Fusion, 65(5), Article ID 056008.
Open this publication in new window or tab >>Fast-ion phase-space tomography with wave-particle interactions in the ion cyclotron frequency range as prior
Show others...
2025 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 65, no 5, article id 056008Article in journal (Refereed) Published
Abstract [en]

The fast-ion distribution function in fusion plasmas can be inferred by inverting Doppler-shifted measurements from fast-ion diagnostics. The full fast-ion distribution function can be parametrised by three constants of motion with the addition of a binary index. However, with a limited number of measurements, cogent prior information must be added to regularise the inverse problem, enabling the reconstruction of the distribution function. In this paper, we demonstrate how to incorporate wave-particle interactions in the ion cyclotron range of frequencies (ICRFs) as prior information with the future ITER tokamak as a test case. We find that the addition of ICRF physics as prior information improves the reconstruction of a test ICRF-heated fast-ion distribution function in ITER using synthetic data based on the planned collective Thomson scattering sightlines and the planned gamma-ray spectroscopy sightlines. The addition of such prior information is beneficial in the case of a limited phase-space coverage of fast-ion diagnostics.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2025
Keywords
fast ions, prior information, tomography, wave-particle interactions
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-554691 (URN)10.1088/1741-4326/adc400 (DOI)001457738900001 ()2-s2.0-105001868174 (Scopus ID)
Available from: 2025-04-16 Created: 2025-04-16 Last updated: 2025-04-16Bibliographically approved
Hägg, L., Eriksson, J., Conroy, S., Ericsson, G., Kirov, K. & Andersson Sundén, E. (2025). Plasma rotation and thermonuclear neutron emission estimates in JET Deuterium Tritium plasmas from neutron spectroscopy. Plasma Physics and Controlled Fusion, 67(3), Article ID 035024.
Open this publication in new window or tab >>Plasma rotation and thermonuclear neutron emission estimates in JET Deuterium Tritium plasmas from neutron spectroscopy
Show others...
2025 (English)In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 67, no 3, article id 035024Article in journal (Refereed) Published
Abstract [en]

Data from the magnetic proton recoil spectrometer (MPRu) high-resolution neutron spectrometer has been used to estimate two fusion plasma quantities, the plasma rotation and the thermonuclear neutron emission. This paper presents a framework for this method and the current results for a selection of plasma discharges from the JET DTE3 campaign. Data collection during DTE3 was preceded by a hardware upgrade in the form of new digitizers, and an update to the data reduction software. The method involves simulations with the TRANSP code, the DRESS code, and a detector response function. The plasma rotation and thermonuclear neutron emission are estimated through a fit of the simulated detector response to the MPRu measurement data. This exploratory analysis studied a selection of DTE3 discharges with high neutron rates. It was found that the rotation was typically in the range 1.5 x 105 to 2.5 x 105 rad s−1 and that neutrons from thermonuclear reactions constitute about 10%–30% of the total neutron emission. For the studied discharges, the neutron emissivity is strongly weighted to the plasma core. Due to the MPRu line of sight passing through the plasma core twice, the plasma rotation and the thermonuclear neutron emission are estimated in the core. This method has the potential to provide complementary data points to other diagnostics.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2025
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-545703 (URN)10.1088/1361-6587/adb5b8 (DOI)001431399100001 ()2-s2.0-85219123648 (Scopus ID)
Available from: 2024-12-19 Created: 2024-12-19 Last updated: 2025-03-13Bibliographically approved
Järleblad, H., Reman, B. C., Dong, Y., Nocente, M., Eriksson, J., Valentini, A., . . . Salewski, M. (2025). Reconstruction of the fast-ion deuterium distribution in a tritium-rich plasma in the JET DTE2 campaign. Nuclear Fusion, 65(1), Article ID 016060.
Open this publication in new window or tab >>Reconstruction of the fast-ion deuterium distribution in a tritium-rich plasma in the JET DTE2 campaign
Show others...
2025 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 65, no 1, article id 016060Article in journal (Refereed) Published
Abstract [en]

An important step on the way to future fusion power plants was the 2021 deuterium-tritium experimental campaign (DTE2) at the Joint European Torus (JET), in which crucial DT physics was investigated. In this study, we have reconstructed the fast-ion deuterium distribution function in JET discharge 99971 which broke the former fusion energy record. It is the first time that the fast-ion distribution has been reconstructed from experimental data in a DT discharge. The reconstruction shows that the fast-ion deuterium distribution is anisotropic, with a bias towards co-going ions (p > 0). The fast-ion deuterium distribution likely peaks in energy (E) at around E∼60-70 keV and has a marginal high-energy tail ( E≥∼180 keV). Furthermore, an orbit analysis shows that the fast-ion distribution is composed of mostly co-passing orbits (50%), trapped orbits (21%) and counter-passing orbits (27%), as well as a small population of potato orbits (1.7%) and counter-stagnation orbits (0.3%). The orbit-type constituents of the neutron measurements are distributed in similar fractions.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2025
Keywords
DT, fast-ion distribution, tomographic reconstruction, JET, slowing-down regularization, neutron diagnostics, weight functions
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-546528 (URN)10.1088/1741-4326/ad9b39 (DOI)001380560600001 ()
Funder
EU, European Research Council, 101052200
Available from: 2025-01-10 Created: 2025-01-10 Last updated: 2025-01-10Bibliographically approved
Murari, A., Andersson Sundén, E., Cecconello, M., Conroy, S., Ericsson, G., Eriksson, B., . . . Zychor, I. (2024). A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors. Nature Communications, 15(1), Article ID 2424.
Open this publication in new window or tab >>A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
Show others...
2024 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 15, no 1, article id 2424Article in journal (Refereed) Published
Abstract [en]

The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices. Confining plasma and managing disruptions in tokamak devices is a challenge. Here the authors demonstrate a method predicting and possibly preventing disruptions and macroscopic instabilities in tokamak plasma using data from JET.

Place, publisher, year, edition, pages
NATURE PORTFOLIO, 2024
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-555347 (URN)10.1038/s41467-024-46242-7 (DOI)001187425700022 ()38499564 (PubMedID)
Note

For complete list of authors see http://dx.doi.org/10.1038/s41467-024-46242-7

Available from: 2025-04-28 Created: 2025-04-28 Last updated: 2025-04-28Bibliographically approved
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
Show others...
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
Kirov, K. K., Auriemma, F., Bonofiglo, P. J., Challis, C. D., De la Luna, E., Eriksson, J., . . . Van Eester, D. (2024). Analysis of fusion alphas interaction with RF waves in D-T plasma at JET. Nuclear Fusion, 64(8), Article ID 086011.
Open this publication in new window or tab >>Analysis of fusion alphas interaction with RF waves in D-T plasma at JET
Show others...
2024 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 64, no 8, article id 086011Article in journal (Refereed) Published
Abstract [en]

This work studies the influence of radio frequency (RF) waves in the ion cyclotron resonance heating (ICRH) range of frequencies on fusion alphas during the recent JET D-T campaign. Fusion alphas from D-T reactions are created with energies of about 3.5 MeV and therefore have significant Doppler shifts enabling synergistic interactions between them and RF waves at a broad range of frequencies, including the ones foreseen for future fusion machines in ITER (Schneider et al 2021 Nucl. Fusion 61 126058) and SPARC (Creely et al 2020 J. Plasma Phys. 86 865860502). Resonant interactions between RF waves and alphas, also called synergistic effects, will modify the alpha distribution and ultimately will have an impact on alpha orbit losses and heating. Data from JET 3.43 T/2.3 MA pulses based on the hybrid scenario (Hobirk et al 2023 Nucl. Fusion; Hobirk et al 29th IAEA FEC23 Conf. (16-21 October 2023); Challis et al 48th EPS Conf. on Plasma Physics (27 June-1 July 2022) during the DTE2 campaign (Maggi et al 2023 Nucl. Fusion)) were used for the analysis in this study. The impact of synergistic effects on alpha orbit losses and alpha heating are assessed. The conclusions are based on the analysis of experimental data for fast alpha losses, i.e. measurements from neutral particle analyser (NPA), fast ion losses scintillator detector, Faraday cups (FCs), and TRANSP (Hawryluk et al 1980 Physics of Plasmas Close to Thermonuclear Conditions vol 1 (CEC) pp 19-46) simulations. Experimental data and TRANSP analysis indicates that there are indeed changes in the alpha distribution function (DF) due to interaction with RF waves. Data from the NPA show increased 4He flux in the range from a few hundred keV up to 800 keV for pulses with RF power, while TRANSP clearly shows modifications in the fast alpha DF for these energies. Data from the scintillator detector and the FCs were compared for pulses with and without ICRH power and versus cases with enhanced alpha losses due to MHD activity. The trends from these diagnostics consistently show no additional alpha losses due to interaction with RF waves. TRANSP predictions for the impact of ynergistic effects on alpha heating show up to a 42% increase in alpha electron heating and up to a 25% increase in alpha ion heating. These effects, however, become negligibly small, less than 1%, when alpha heating is compared to the total auxiliary heating power in the investigated JET pulses.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2024
Keywords
JET, DT plasma, alphas, synergistic effects, ICRH
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-534818 (URN)10.1088/1741-4326/ad4b3c (DOI)001249955600001 ()
Available from: 2024-07-10 Created: 2024-07-10 Last updated: 2024-07-10Bibliographically approved
Mantica, P., Auriemma, F., Casiraghi, I., Gallart, D., Kirov, K., Lerche, E., . . . Van Eester, D. (2024). Detection of alpha heating in JET-ILW DT plasmas by a study of the electron temperature response to ICRH modulation. Nuclear Fusion, 64(8), Article ID 086001.
Open this publication in new window or tab >>Detection of alpha heating in JET-ILW DT plasmas by a study of the electron temperature response to ICRH modulation
Show others...
2024 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 64, no 8, article id 086001Article in journal (Refereed) Published
Abstract [en]

In the JET DTE2 campaign a new method was successfully tested to detect the heating of bulk electrons by alpha-particles, using the dynamic response of the electron temperature T e to the modulation of ion cyclotron resonance heating (ICRH). A fundamental deuterium (D) ICRH scheme was applied to a tritium-rich hybrid plasma with D-neutral beam injection (NBI). The modulation of the ion temperature T i and of the ICRH accelerated deuterons leads to modulated alpha-heating with a large delay with respect to other modulated electron heating terms. A significant phase delay of similar to 40 degrees is measured between central T e and T i, which can only be explained by alpha-particle heating. Integrated modelling using different models for ICRH absorption and ICRH/NBI interaction reproduces the effect qualitatively. Best agreement with experiment is obtained with the European Transport Solver/Heating and Current Drive workflow.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2024
Keywords
tokamak, DT plasmas, alpha heating, ICRH modulation
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-534815 (URN)10.1088/1741-4326/ad52aa (DOI)001249955400001 ()
Funder
EU, Horizon 2020, 101052200
Available from: 2024-07-11 Created: 2024-07-11 Last updated: 2024-07-11Bibliographically 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
Show others...
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
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; Publications
MacLean, C. L., Cecconello, M., Allan, S., Grove, C. L., Worrall, R. & Lennon, K. (2025). Absolute neutron emission estimate on MAST Upgrade based on activation foil measurements. Plasma Physics and Controlled Fusion, 67(6), Article ID 065011.
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0892-3358

Search in DiVA

Show all publications