| 21. |
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| 22. |
- Giacomelli, Luca, et al.
(författare)
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Comparison of neutron emission spectra for D and DT plasmas with auxiliary heating
- 2005
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Ingår i: The European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; :33, s. 235-241
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Tidskriftsartikel (refereegranskat)abstract
- The DT experimental campaign on JET (1997) represents a major step forward for neutronemission spectroscopy (NES) diagnostic through the high quality data collected by the Magnetic ProtonRecoil (MPR) spectrometer. These data for different DT plasma heating scenarios were analyzed here todetermine the underlying fuel ion populations which in turn were used to project the 2.5-MeV neutronemission spectra for deuterium plasmas. The results on neutron spectra for DT and D plasmas in thesame conditions were compared in order to determine the plasma information that could be expectedfrom NES diagnosis of D plasmas and the instrumental characteristics that would be required. FutureNES experiments would make dual sight line observations possible and the added diagnostic value is alsoassessed based on the present results.
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| 23. |
- Giacomelli, L., et al.
(författare)
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Conceptual studies of gamma ray diagnostics for DEMO control
- 2018
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Ingår i: Fusion engineering and design. - : ELSEVIER SCIENCE SA. - 0920-3796 .- 1873-7196. ; 136, s. 1494-1498
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Tidskriftsartikel (refereegranskat)abstract
- The future tokamak demonstration fusion reactor (DEMO) will operate at unprecedented physical and technological conditions where high reliability of the system components is required. The conceptual study of a suite of DEMO diagnostics is on-going. Among these, a Gamma-Ray Spectrometric Instrument (GRSI) is being investigated to assess its performance and information quality in view of DEMO control. The GRSI foresees radial orthogonal multi-line of sight viewing DEMO plasma across its poloidal section as a further development of the Gamma-Ray Camera of JET and of the Radial Gamma-Ray Spectrometers proposed for ITER but with stricter technological constraints. These include surface availability in the Tritium Breeding Blankets of DEMO vessel inner wall for diagnostics collimators openings, diagnostics distance from the plasma, neutron irradiation and activation of the reactor structures. On DEMO the gamma-ray (gamma) emission from DT plasmas consists of T(d,gamma)He-5 (E gamma = 16.63 MeV) and T(p,gamma)He-4 (E gamma = 19.81 MeV) reactions which for their high E gamma would allow in principle for background-free measurements. This work reports the assessment on the GRSI diagnostic capability. Reactions cross sections are assessed and used for the calculations of the reactions gamma emission energy spectrum under DEMO DT plasma conditions and compared with 14 MeV neutron emissions before and after the GRSI collimator. Investigation of the GRSI gamma spectrometers performance is also presented. Measurement of the gamma emission intensity of T(d,gamma)He-5 can be in principle used as an independent assessment of DEMO DT plasmas fusion power.
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| 24. |
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| 25. |
- Giacomelli, L., et al.
(författare)
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Overview on the progress of the conceptual studies of a gamma ray spectrometer instrument for DEMO
- 2022
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Ingår i: Journal of Instrumentation. - : IOP Publishing Ltd. - 1748-0221. ; 17:8
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Tidskriftsartikel (refereegranskat)abstract
- The future DEMO tokamak will be equipped with a suite of diagnostics which will operate as sensors to monitor and control the position and operation parameters of DT plasmas. Among the suite of sensors, an integrated neutron and gamma-ray diagnostic system is also studied to verify its capability and performance in detecting possible DEMO plasma position variations and contribute to the feedback system in maintaining DEMO DT plasma in stable conditions. This work describes the progress of the conceptual study of the gamma-ray diagnostic for DEMO reactor performed during the first Work-Package contract 2015-2020. The reaction of interest for this Gamma-Ray Spectrometer Instrument (GRSI) consists of D(T, gamma)He-5 with the emission of 16.63 MeV gamma rays. Due to DEMO tokamak design constraints, the gamma and neutron diagnostics are integrated, both featuring multi-line of sight (camera type), viewing DEMO plasma radially with vertical (12) and horizontal (13) viewing lines to diagnose the. and neutron emission from the DT plasma poloidal section. The GRSI design is based on the investigation of the reaction cross sections, on the calculations performed with GENESIS and MCNP simulation codes and on the physics and geometry constrains of the integrated instrument. GRSI features long collimators which diameters are constrained by the neutron flux at the neutron detectors of the Radial Neutron Camera (RNC) system placed in front, which are key to control DEMO DT plasma position. For these reasons, only few GRSI parameters can be independently selected to optimize its performance. Among these, the choice of the collimator diameters at the back side of the neutron detector box up to the GRSI detector, the use of LiH neutron attenuators in front of the GRSI detectors, the GRSI detector material and shielding. The GRSI detector is based on commercial LaBr3(Ce) inorganic scintillating crystal coupled with a photomultiplier tube or a silicon photomultiplier. They are designed to operate at high count rate although GRSI geometry constraints severely impact on this feature. The GRSI can also provide an independent assessment of DEMO DT fusion power and T burning.
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| 26. |
- Gorini, Giuseppe, et al.
(författare)
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Neutron Emission from Beam-Injected Fast Tritons in JET Plasmas with Reversed or Monotonic Magnetic Shear.
- 2004
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Ingår i: 31st EPS Conference on Plasma Physics. ; , s. 4-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The neutron emission from fast tritons in plasmas with different magnetic shearconfigurations has been investigated in a dedicated experiment on JET. Short pulses ofneutral beam injection were used to deposit fast tritons in deuterium plasmas. By comparingthe measured neutron yield with predictions based on DT reaction calculations, fast tritonlosses can be assessed. The latter are expected to be very low according to neoclassicalpredictions based on Fokker-Planck simulation [1]. Much larger “anomalous” beam-ionlosses (up to 40%) have been reported in TFTR experiments for plasma conditions withreversed magnetic shear [2]. The TFTR experiments indicated an excess DT rate in thesimulation and, to a lesser extent, in the DD rate and plasma stored energy. This wasinterpreted as anomalous beam-ion loss associated with reverse shear due to an unidentifiedloss mechanism. Evidence of a similar effect was searched for in the JET experimentsreported in this paper.
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| 27. |
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| 28. |
- Hellesen, Carl, 1980-, et al.
(författare)
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Neutron spectroscopy measurements and modeling of neutral beam heating fast ion dynamics
- 2010
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 52:8, s. 085013-
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Tidskriftsartikel (refereegranskat)abstract
- The energy spectrum of the neutron emission from beam-target reactions in fusion plasmas at the Joint European Torus (JET) has been investigated. Different beam energies as well as injection angles were used. Both measurements and simulations of the energy spectrum were done. The measurements were made with the time-of-flight spectrometer TOFOR. Simulations of the neutron spectrum were based on first-principle calculations of neutral beam deposition profiles and the fast ion slowing down in the plasma using the code NUBEAM, which is a module of the TRANSP package. The shape of the neutron energy spectrum was seen to vary significantly depending on the energy of the beams as well as the injection angle and the deposition profile in the plasma. Cross validations of the measured and modeled neutron energy spectra were made, showing a good agreement for all investigated scenarios.
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| 29. |
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| 30. |
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