| 581. |
- Santoro, V., et al.
(författare)
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The HighNESS Project at the European Spallation Source : Current Status and Future Perspectives
- 2024
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Ingår i: Nuclear science and engineering. - 0029-5639 .- 1943-748X. ; 198:1, s. 31-63
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Tidskriftsartikel (refereegranskat)abstract
- The European Spallation Source (ESS), presently under construction in Lund, Sweden, is a multidisciplinary international laboratory that, once completed at full specifications, will operate the world's most powerful pulsed neutron source. Supported by a 3 M Euro Research and Innovation Action within the European Union Horizon 2020 program, a design study (HighNESS) is now underway to develop a second neutron source located below the spallation target. Compared to the first source, which is located above the spallation target and designed for high cold and thermal brightness, the new source is being optimized to deliver higher intensity and a shift to longer wavelengths in the spectral regions of cold neutrons (CNs) (2 to 20 & Aring;), very cold neutrons (VCNs) (10 to 120 & Aring;), and ultracold neutrons (UCNs) (> 500 & Aring;). The second source consists of a large liquid deuterium moderator to deliver CNs and serve secondary VCN and UCN sources, for which different options are under study. These new sources will boost several areas of condensed matter research and will provide unique opportunities in fundamental physics. The HighNESS project is now entering its last year, and we are working toward the Conceptual Design Report of the ESS upgrade. In this paper, results obtained in the first 2 years, ongoing developments, and future perspectives are described.
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| 582. |
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| 583. |
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| 584. |
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| 585. |
- Tardocchi, M, et al.
(författare)
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Neutron spectrometry of radio-frequency heated deuterium-tritium plasmas
- 1999
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Ingår i: REVIEW OF SCIENTIFIC INSTRUMENTS. - 0034-6748. ; 70:1, s. 1171-1175
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Tidskriftsartikel (refereegranskat)abstract
- Spectrometry of the neutron emission has been used to probe the nonthermal features of the fuel ion velocity distributions in tokamak plasmas, especially, those arising from auxiliary heating. The first time resolved measurements are reported from the use
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| 586. |
- Tardocchi, M, et al.
(författare)
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Time resolved neutron emission spectroscopy of DT plasmas with ion cyclotron resonance heating
- 2001
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Ingår i: REVIEW OF SCIENTIFIC INSTRUMENTS. - : AMER INST PHYSICS. - 0034-6748. ; 72:1, s. 836-840
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Tidskriftsartikel (refereegranskat)abstract
- The energy spectrum of the DT neutron emission was measured in experiments carried out at JET for plasmas of deuterium-tritium heated with different ion cyclotron resonance heating (ICRH) schemes. The spectrum was measured with the magnetic proton recoil
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| 587. |
- Van Eester, D., et al.
(författare)
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Minority and mode conversion heating in (He-3)-H JET plasmas
- 2012
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 54:7, s. 074009-
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Tidskriftsartikel (refereegranskat)abstract
- Radio frequency (RF) heating experiments have recently been conducted in JET (He-3)-H plasmas. This type of plasmas will be used in ITER's non-activated operation phase. Whereas a companion paper in this same PPCF issue will discuss the RF heating scenario's at half the nominal magnetic field, this paper documents the heating performance in (He-3)-H plasmas at full field, with fundamental cyclotron heating of He-3 as the only possible ion heating scheme in view of the foreseen ITER antenna frequency bandwidth. Dominant electron heating with global heating efficiencies between 30% and 70% depending on the He-3 concentration were observed and mode conversion (MC) heating proved to be as efficient as He-3 minority heating. The unwanted presence of both He-4 and D in the discharges gave rise to 2 MC layers rather than a single one. This together with the fact that the location of the high-field side fast wave (FW) cutoff is a sensitive function of the parallel wave number and that one of the locations of the wave confluences critically depends on the He-3 concentration made the interpretation of the results, although more complex, very interesting: three regimes could be distinguished as a function of X[He-3]: (i) a regime at low concentration (X[He-3] < 1.8%) at which ion cyclotron resonance frequency (ICRF) heating is efficient, (ii) a regime at intermediate concentrations (1.8 < X[He-3] < 5%) in which the RF performance is degrading and ultimately becoming very poor, and finally (iii) a good heating regime at He-3 concentrations beyond 6%. In this latter regime, the heating efficiency did not critically depend on the actual concentration while at lower concentrations (X[He-3] < 4%) a bigger excursion in heating efficiency is observed and the estimates differ somewhat from shot to shot, also depending on whether local or global signals are chosen for the analysis. The different dynamics at the various concentrations can be traced back to the presence of 2 MC layers and their associated FW cutoffs residing inside the plasma at low He-3 concentration. One of these layers is approaching and crossing the low-field side plasma edge when 1.8 < X[He-3] < 5%. Adopting a minimization procedure to correlate the MC positions with the plasma composition reveals that the different behaviors observed are due to contamination of the plasma. Wave modeling not only supports this interpretation but also shows that moderate concentrations of D-like species significantly alter the overall wave behavior in He-3-H plasmas. Whereas numerical modeling yields quantitative information on the heating efficiency, analytical work gives a good description of the dominant underlying wave interaction physics.
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| 588. |
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| 589. |
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| 590. |
- Andersson Sundén, Erik, et al.
(författare)
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The thin-foil magnetic proton recoil neutron spectrometer MPRu at JET
- 2009
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 610:3, s. 682-699
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Tidskriftsartikel (refereegranskat)abstract
- Neutrons are produced in fusion energy experiments with both deuterium (D) and deuterium–tritium (DT) plasmas. Neutron spectroscopy is a valuable tool in the study of the underlying fuel ion populations. The magnetic proton recoil neutron spectrometer, originally installed at JET in 1996 for 14-MeV neutron measurements, has been upgraded, with the main aim of improving its signal-to-background ratio (S/B), making measurements of the 2.5-MeV neutron emission in D plasmas possible. The upgrade includes a new focal-plane detector, based on the phoswich technique and consequently less sensitive to background, and a new custom-designed digital data acquisition system based on transient recorder cards. Results from JET show that the upgraded MPRu can measure 2.5-MeV neutrons with S/B=5, an improvement by a factor of 50 compared with the original MPR. S/B of 2.8×104 in future DT experiments is estimated. The performance of the MPRu is exemplified with results from recent D plasma operations at JET, concerning both measurements with Ohmic, ion cyclotron resonance (ICRH) and neutral beam injection (NBI) plasma heating, as well as measurements of tritium burn-up neutrons. The upgraded instrument allows for 2.5-MeV neutron emission and deuterium ion temperature measurements in plasmas with low levels of tritium, a feature necessary for the ITER experiment.
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