| 1. |
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| 2. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Mullins, Niamh, et al.
(författare)
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Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors
- 2022
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Ingår i: Biological Psychiatry. - : Elsevier. - 0006-3223 .- 1873-2402. ; 91:3, s. 313-327
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders.METHODS: We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors.RESULTS: Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged.CONCLUSIONS: Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.
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| 7. |
- Docherty, Anna R, et al.
(författare)
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GWAS Meta-Analysis of Suicide Attempt: Identification of 12 Genome-Wide Significant Loci and Implication of Genetic Risks for Specific Health Factors.
- 2023
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Ingår i: The American journal of psychiatry. - : American Psychiatric Association Publishing. - 1535-7228 .- 0002-953X. ; 180:10, s. 723-738
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Tidskriftsartikel (refereegranskat)abstract
- Suicidal behavior is heritable and is a major cause of death worldwide. Two large-scale genome-wide association studies (GWASs) recently discovered and cross-validated genome-wide significant (GWS) loci for suicide attempt (SA). The present study leveraged the genetic cohorts from both studies to conduct the largest GWAS meta-analysis of SA to date. Multi-ancestry and admixture-specific meta-analyses were conducted within groups of significant African, East Asian, and European ancestry admixtures.This study comprised 22 cohorts, including 43,871 SA cases and 915,025 ancestry-matched controls. Analytical methods across multi-ancestry and individual ancestry admixtures included inverse variance-weighted fixed-effects meta-analyses, followed by gene, gene-set, tissue-set, and drug-target enrichment, as well as summary-data-based Mendelian randomization with brain expression quantitative trait loci data, phenome-wide genetic correlation, and genetic causal proportion analyses.Multi-ancestry and European ancestry admixture GWAS meta-analyses identified 12 risk loci at p values <5×10-8. These loci were mostly intergenic and implicated DRD2, SLC6A9, FURIN, NLGN1, SOX5, PDE4B, and CACNG2. The multi-ancestry SNP-based heritability estimate of SA was 5.7% on the liability scale (SE=0.003, p=5.7×10-80). Significant brain tissue gene expression and drug set enrichment were observed. There was shared genetic variation of SA with attention deficit hyperactivity disorder, smoking, and risk tolerance after conditioning SA on both major depressive disorder and posttraumatic stress disorder. Genetic causal proportion analyses implicated shared genetic risk for specific health factors.This multi-ancestry analysis of suicide attempt identified several loci contributing to risk and establishes significant shared genetic covariation with clinical phenotypes. These findings provide insight into genetic factors associated with suicide attempt across ancestry admixture populations, in veteran and civilian populations, and in attempt versus death.
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| 8. |
- Illana, A., et al.
(författare)
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Coulomb excitation of 74,76Zn
- 2023
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Ingår i: Physical Review C. - 2469-9985. ; 108:4
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Tidskriftsartikel (refereegranskat)abstract
- The first experiment using radioactive beams post-accelerated by the HIE-ISOLDE facility has enabled to obtain a precise set of B(E2) transition probabilities in neutron-rich 74,76Zn isotopes. The resulting B(E2; 2+1→0+1) values are consistent with those determined in earlier REX-ISOLDE measurements. While the B(E2; 4+1→2+1) transition probability in 76Zn is also in agreement with earlier Coulomb-excitation results, the value obtained for 74Zn is considerably lower. For the first time, a spectroscopic quadrupole moment of the 2+1 state was measured for an exotic nucleus in this mass region. A detailed comparison is presented with large-scale shell-model and Monte Carlo shell-model calculations.
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| 9. |
- Doornenbal, P., et al.
(författare)
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RISING: Gamma‐ray Spectroscopy with Radioactive Beams at GSI
- 2007
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 891, s. 99-107
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Konferensbidrag (refereegranskat)abstract
- The Rare Isotope Spectroscopic INvestigation at GSI (RISING) project is a major pan‐European collaboration. Its physics aims are the studies of exotic nuclear matter with abnormal proton‐to‐neutron ratios compared with naturally occurring isotopes. RISING combines the FRagment Separator (FRS) which allows relativistic energies and projectile fragmentation reactions with EUROBALL Ge Cluster detectors for γ spectroscopic research. The RISING setup can be used in two different configurations. Either the nuclei of interest are investigated after being stopped or the heavy ions hit a secondary target at relativistic energies and the thereby occurring excitations are studied. For the latter case, MINIBALL Ge detectors and the HECTOR array are used in addition. Example achievements of the Fast Beam setup are presented and compared to various shell model calculations, while for the Stopped Beam setup initial results are shown.
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| 10. |
- Kondo, Y., et al.
(författare)
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First observation of 28 O
- 2023
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 620:7976, s. 965-970
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Tidskriftsartikel (refereegranskat)abstract
- Subjecting a physical system to extreme conditions is one of the means often used to obtain a better understanding and deeper insight into its organization and structure. In the case of the atomic nucleus, one such approach is to investigate isotopes that have very different neutron-to-proton (N/Z) ratios than in stable nuclei. Light, neutron-rich isotopes exhibit the most asymmetric N/Z ratios and those lying beyond the limits of binding, which undergo spontaneous neutron emission and exist only as very short-lived resonances (about 10−21s), provide the most stringent tests of modern nuclear-structure theories. Here we report on the first observation of 28O and 27O through their decay into 24O and four and three neutrons, respectively. The 28O nucleus is of particular interest as, with the Z = 8 and N = 20 magic numbers1,2, it is expected in the standard shell-model picture of nuclear structure to be one of a relatively small number of so-called ‘doubly magic’ nuclei. Both 27O and 28O were found to exist as narrow, low-lying resonances and their decay energies are compared here to the results of sophisticated theoretical modelling, including a large-scale shell-model calculation and a newly developed statistical approach. In both cases, the underlying nuclear interactions were derived from effective field theories of quantum chromodynamics. Finally, it is shown that the cross-section for the production of 28O from a 29F beam is consistent with it not exhibiting a closed N = 20 shell structure.
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| 11. |
- Wang, H., et al.
(författare)
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Intruder configurations in 29 Ne at the transition into the island of inversion: Detailed structure study of 28 Ne
- 2023
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 843
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Tidskriftsartikel (refereegranskat)abstract
- Detailed γ-ray spectroscopy of the exotic neon isotope 28Ne has been performed for the first time using the one-neutron removal reaction from 29Ne on a liquid hydrogen target at 240 MeV/nucleon. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for 28Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N=20 and N=28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.
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| 12. |
- Maierbeck, P., et al.
(författare)
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Structure of 55Ti from relativistic one-neutron knockout
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 675:1, s. 22-27
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.
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| 13. |
- Meixner, Margaret, et al.
(författare)
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Herschel and ALMA measurements of dust and molecules in supernova 1987A
- 2013
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Ingår i: Proceedings of Science. - 1824-8039. ; Part F113823
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Konferensbidrag (refereegranskat)abstract
- Dust production by supernovae is important in the dust life cycle of a galaxy. The explosion of SN 1987A was the nearest SN detected in the last 400 years, allowing us detailed studies of contemporary evolution of a supernova for the first time. In 2011, Matsuura et al. reported 0.4-0.7 M of dust in SN 1987A based on Herschel HERITAGE survey data, which is surprisingly large compared to prior measurements of supernovae. In this paper, we present our follow-up studies of this important discovery about SN 1987A using the Herschel Space Observatory and the Atacama Large Millimeter Array (ALMA). We highlight two important results, the detection of cold molecular gas and dust in the ejected material of SN 1987A. Our results suggest that SNe are significant producers of dust and molecules, as well as heavy elements, driving chemical evolution of galaxies.
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| 14. |
- Rosiak, D., et al.
(författare)
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Enhanced Quadrupole and Octupole Strength in Doubly Magic Sn 132
- 2018
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Ingår i: Physical Review Letters. - 0031-9007. ; 121:25
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Tidskriftsartikel (refereegranskat)abstract
- The first 2+ and 3- states of the doubly magic nucleus Sn132 are populated via safe Coulomb excitation employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with the highly efficient MINIBALL array. The Sn132 ions are accelerated to an energy of 5.49 MeV/nucleon and impinged on a Pb206 target. Deexciting γ rays from the low-lying excited states of the target and the projectile are recorded in coincidence with scattered particles. The reduced transition strengths are determined for the transitions 0g.s.+→21+, 0g.s.+→31-, and 21+→31- in Sn132. The results on these states provide crucial information on cross-shell configurations which are determined within large-scale shell-model and Monte Carlo shell-model calculations as well as from random-phase approximation and relativistic random-phase approximation. The locally enhanced B(E2;0g.s.+→21+) strength is consistent with the microscopic description of the structure of the respective states within all theoretical approaches. The presented results of experiment and theory can be considered to be the first direct verification of the sphericity and double magicity of Sn132.
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| 15. |
- Schwertel, S., et al.
(författare)
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One-neutron knockout from Sc51-55
- 2012
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 48:Dec., s. 191-10
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a one-neutron knockout experiment at relativistic energies of approximate to 420 A MeV on Sc51-55 using the GSI Fragment Separator as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the contributions corresponding to knockout from the nu p(1/2), nu p(3/2), (L = 1) and nu f(7/2), nu f(5/2) (L = 3) neutron orbitals. The observed L = 1 and L = 3 contributions are compared with theoretical cross-sections using eikonal knockout theory and spectroscopic factors from shell model calculations using the GXPF1A interaction. The measured inclusive knockout cross-sections generally follow the trends expected theoretically and given by the spectroscopic strength predicted from the shell model calculations. However, the deduced L = 1 cross-sections are generally 30-40% higher while the L = 3 contributions are about a factor of two smaller than predicted. This points to a promotion of neutrons from the nu f(7/2) to the nu p(3/2) orbital indicating a weakening of the N = 28 shell gap in these nuclei. While this is not predicted for the phenomenological GXPF1A interaction such a weakening is predicted by recent calculations using realistic low-momentum interactions V-lowk obtained by evolving a chiral N3LO nucleon-nucleon potential.
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| 16. |
- De Marco, O., et al.
(författare)
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The messy death of a multiple star system and the resulting planetary nebula as observed by JWST
- 2022
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Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 6:12, s. 1421-1432
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Tidskriftsartikel (refereegranskat)abstract
- Planetary nebulae—the ejected envelopes of red giant stars—provide us with a history of the last, mass-losing phases of 90% of stars initially more massive than the Sun. Here we analyse images of the planetary nebula NGC 3132 from the James Webb Space Telescope (JWST) Early Release Observations. A structured, extended hydrogen halo surrounding an ionized central bubble is imprinted with spiral structures, probably shaped by a low-mass companion orbiting the central star at about 40–60 au. The images also reveal a mid-infrared excess at the central star, interpreted as a dusty disk, which is indicative of an interaction with another closer companion. Including the previously known A-type visual companion, the progenitor of the NGC 3132 planetary nebula must have been at least a stellar quartet. The JWST images allow us to generate a model of the illumination, ionization and hydrodynamics of the molecular halo, demonstrating the power of JWST to investigate complex stellar outflows. Furthermore, new measurements of the A-type visual companion allow us to derive the value for the mass of the progenitor of a central star with excellent precision: 2.86 ± 0.06 M⊙. These results serve as pathfinders for future JWST observations of planetary nebulae, providing unique insight into fundamental astrophysical processes including colliding winds and binary star interactions, with implications for supernovae and gravitational-wave systems.
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| 17. |
- Matsuura, M., et al.
(författare)
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Herschel Detects a Massive Dust Reservoir in Supernova 1987A
- 2011
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 333:6047, s. 1258-1261
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Tidskriftsartikel (refereegranskat)abstract
- We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.
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| 18. |
- Ueta, T., et al.
(författare)
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The Herschel Planetary Nebula Survey (HerPlaNS) I. Data overview and analysis demonstration with NGC 6781
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 565, s. A36-
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Tidskriftsartikel (refereegranskat)abstract
- Context. This is the first of a series of investigations into far-IR characteristics of 11 planetary nebulae (PNe) under the Herschel Space Observatory open time 1 program, Herschel Planetary Nebula Survey (HerPlaNS). Aims. Using the HerPlaNS data set, we look into the PN energetics and variations of the physical conditions within the target nebulae. In the present work, we provide an overview of the survey, data acquisition and processing, and resulting data products. Methods. We performed (1) PACS/SPIRE broadband imaging to determine the spatial distribution of the cold dust component in the target PNe and (2) PACS/SPIRE spectral-energy-distribution and line spectroscopy to determine the spatial distribution of the gas component in the target PNe. Results. For the case of NGC 6781, the broadband maps confirm the nearly pole-on barrel structure of the amorphous carbon-rich dust shell and the surrounding halo having temperatures of 26-40 K. The PACS/SPIRE multiposition spectra show spatial variations of far-.IR lines that reflect the physical stratification of the nebula. We demonstrate that spatially resolved far-IR line diagnostics yield the (T-e, n(e)) profiles, from which distributions of ionized, atomic, and molecular gases can be determined. Direct comparison of the dust and gas column mass maps constrained by the HerPlaNS data allows to construct an empirical gas-to-dust mass ratio map, which shows a range of ratios with the median of 195 +/- 110. The present analysis yields estimates of the total mass of the shell to be 0.86 M-circle dot, consisting of 0.54 M-circle dot of ionized gas, 0.12 M-circle dot of atomic gas, 0.2 M-circle dot of molecular gas, and 4 x 10(-3) M-circle dot of dust grains. These estimates' also suggest that the central star of about 1.5 M-circle dot initial mass is terminating its PN evolution onto the white dwarf cooling track. Conclusions. The HerPlaNS data provide various diagnostics for both the dust and gas components in a spatially resolved manner. In the forthcoming papers of the HerPlaNS series we will explore the HerPlaNS data set fully for the entire sample of 11 PNe.
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| 19. |
- Ueta, T., et al.
(författare)
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Herschel Planetary Nebula Survey (HerPlaNS)
- 2014
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Ingår i: Asymmetrical Planetary Nebulae VI conference, Proceedings of the conference held 4-8 November, 2013. ; , s. 106-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Herschel Planetary Nebula Survey (HerPlaNS) is one of the largest Open Time programs carried out by the Herschel Space Observatory, by which we simultaneously probe the dust and gas components of the circumstellar environments of evolved stars. HerPlaNS is part of a community-wide panchromatic (from X-ray to Radio) observational initiative to furnish substantial PN data resources that would allow us - PN astronomers - to tackle a multitude of issues in PN physics. In this contribution we will give a general overview of the survey and a glimpse of what the data can tell us using NGC 6781 as an example.
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| 20. |
- Ueta, T., et al.
(författare)
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Planetary Nebula dust haloes revealed by Herschel
- 2013
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Ingår i: Proceedings of Science. - Trieste, Italy : Sissa Medialab. - 1824-8039.
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Konferensbidrag (refereegranskat)abstract
- Herschel Planetary Nebula Survey (HerPlaNS) is a far-IR imaging and spectroscopic survey of planetary nebulae, performedwith the Herschel Space Observatory, aiming at (1) establishing the spatially-resolved far-IR characteristics of the target nebulae and (2) understanding the energetics and shaping history of the circumstellar nebulae. Below we briefly demonstrate the breadth and depth of the HerPlaNS data set using one of the targets, NGC6781, as an example, and explore expectations in the era of SPICA, the next-generation far-IR mission.
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| 21. |
- Wraith, Calvin, et al.
(författare)
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Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers
- 2017
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 771, s. 385-391
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Tidskriftsartikel (refereegranskat)abstract
- Collinear laser spectroscopy was performed on Zn (Z = 30) isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N = 33–49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N = 50. Exactly one longlived (>10 ms) isomeric state has been established in each 69–79Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell–model calculations in the f5pg9 and fpg9d5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder Iπ = 1/2+ isomer in 79Zn is reproduced only if the νs1/2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction.The spin and moments of the low-lying isomeric state in 73Zn suggest a strong onset of deformation at N = 43, while the progression towards 79Zn points to the stability of the Z = 28 and N = 50 shell gaps, supporting the magicity of 78Ni
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| 22. |
- Gorska, M., et al.
(författare)
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Nuclear Structure far off Stability - RISING Campaigns
- 2007
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Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 38:4, s. 1219-1228
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear structure studies at CST attracted recently increased interest for the results of present activities as well as for the future project FAIR. A broad range of physics phenomena can be addressed by high-resolution in-beam gamma-ray spectroscopy experiments with radioactive beams offered within the Rare Isotopes Spectroscopic INvestigation at GSI (RISING) project. It combined the EUROBALL Ge-Cluster detectors, the MINIBALL Ce detectors, the HECTOR-BaF detectors, and the fragment separator FRS. The secondary beams produced at relativistic energies were used for Coulomb excitation or secondary fragmentation experiments to study projectile like nuclei by measuring de-excitation photons. The first results of the "fast beam campaign" is discussed in comparison to various shell model calculations. The discussion focuses on the N = 32, 34 sub-shell closure based on neutron rich Cr isotopes. Alternatively, the relativistic radioactive beams, both in their ground and isomeric states, were implanted and their decay could be investigated. The "stopped beam campaign" has started in October 2005 with a series of g-factor measurements. It continued from February 2006 with the next, configuration and the main goal of identification of new isomers and angular momentum population in fragmentation reactions.
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| 23. |
- Lee, S., et al.
(författare)
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Tritium distributions in castellated structures of Be limiter tiles from JET-ITER-like wall experiments
- 2023
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Ingår i: Nuclear Fusion. - : IOP Publishing Ltd. - 0029-5515 .- 1741-4326. ; 63:4
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Tidskriftsartikel (refereegranskat)abstract
- Tritium retention in the castellated structure of beryllium limiters used in JET with the ITER-like wall (ILW) during the first (ILW1), third (ILW3) and all three (ILW1-3) campaigns were examined and evaluated. Tritium was deposited on the surfaces inside the castellation grooves together with deuterium, beryllium, oxygen, carbon and small amounts of metallic impurities such as nickel, copper and tungsten. The tritium content after the ILW1 campaign was greater than after the ILW3 campaign. This is attributed to the steadily decreasing amount of carbon impurities in JET from campaign to campaign. The majority of tritium was retained in shallow regions in the grooves, up to 2 mm from the entrance to the gap. It was comparable on all sides of the castellation, i.e. no difference has been detected between the toroidal and poloidal gaps. Secondly, the tritium retention in the gaps was similar on all specimens independent of their position in the tokamak, while the retention on the plasma-facing surfaces clearly depended on the tile position. The tritium deposition patterns in the castellation were also compared with the deuterium distribution determined in earlier studies.
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| 24. |
- Masuzakil, S., et al.
(författare)
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Analyses of microstructure, composition and retention of hydrogen isotopes in divertor tiles of JET with the ITER-like wall
- 2017
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Ingår i: Physica Scripta. - : IOP PUBLISHING LTD. - 0031-8949 .- 1402-4896. ; T170
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Tidskriftsartikel (refereegranskat)abstract
- Results of the comprehensive surface analyses of divertor tiles and dusts retrieved from JET after the first ITER-like wall campaign (2011-2012) are presented. The samples cored from the divertor tiles were analyzed. Numerous nano-size bubble-like structures were observed in the deposition layer on the apron of the inner divertor tile, and a beryllium dust with the same structures were found in the matter collected from the inner divertor after the campaign. This suggests that the nano-size bubble-like structures can make the deposition layer to become brittle and may lead to cracking followed by dust generation. X-ray photoelectron spectroscopy analyses of chemical states of species in the deposition layers identified the formation of beryllium-tungsten intermetallic compounds on an inner vertical tile. Different tritium retention profiles along the divertor tiles were observed at the top surfaces and at deeper regions of the tiles by using the imaging plate technique.
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| 25. |
- Oka, M., et al.
(författare)
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Electron Scattering by Low-frequency Whistler Waves at Earth?s Bow Shock
- 2019
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Ingår i: Astrophysical Journal. - : Institute of Physics (IOP). - 0004-637X .- 1538-4357. ; 886:1
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Tidskriftsartikel (refereegranskat)abstract
- Electrons are accelerated to nonthermal energies at shocks in space and astrophysical environments. While shock drift acceleration (SDA) has been considered a key process of electron acceleration at Earth?s bow shock, it has also been recognized that SDA needs to be combined with an additional stochastic process to explain the observed power-law energy spectra. Here, we show mildly energetic (?0.5 keV) electrons are locally scattered (and accelerated while being confined) by magnetosonic-whistler waves within the shock transition layer, especially when the shock angle is large (
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