| 1. |
- Järleblad, H., et al.
(författare)
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A framework for synthetic diagnostics using energetic-particle orbits in tokamaks
- 2024
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Ingår i: Computer Physics Communications. - : Elsevier. - 0010-4655 .- 1879-2944. ; 294
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Järleblad, H., et al.
(författare)
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Fast-ion orbit origin of neutron emission spectroscopy measurements in the JET DT campaign
- 2024
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Ingår i: Nuclear Fusion. - : Institute of Physics Publishing (IOPP). - 0029-5515 .- 1741-4326. ; 64:2
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Rud, M., et al.
(författare)
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Diagnostic weight functions in constants-of-motion phase-space
- 2024
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Ingår i: Nuclear Fusion. - : Institute of Physics Publishing (IOPP). - 0029-5515 .- 1741-4326. ; 64:3
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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