| 1. |
- Andersson Sundén, Erik, et al.
(författare)
-
Instrumentation for neutron emission spectrometry in use at JET
- 2010
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 623:2, s. 681-685
-
Tidskriftsartikel (refereegranskat)abstract
- The present contribution discusses two neutron spectrometers: the time-of-flight spectrometer (TOFOR) and the magnetic proton recoil spectrometer (MPRu). TOFOR uses fast plastic scintillators equipped with digital time-stamping electronics to register the time of each eligible scintillation event. The time trace for each detector is acquired practically dead-time free. The detectors of the MPRu are of phoswich type and each detector is connected to a digital transient recorder card that stores the full waveform for an event. By using phoswich detectors, pulse-shape discrimination techniques can be applied offline to distinguish signal events from background. A future upgrade of TOFOR could be digital “hybrid” cards, which store correlated time and waveform information. This information can be used to decrease the background level in the ttof spectrum, thereby increasing the operating range.
|
|
| 2. |
- Belli, Francesco, et al.
(författare)
-
Conceptual Design, Development and Preliminary Tests of a Compact Neutron Spectrometer for the JET Experiment
- 2012
-
Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 59:5, s. 2512-2519
-
Tidskriftsartikel (refereegranskat)abstract
- A Compact Neutron Spectrometer (CNS) has been developed to measure the neutron emission spectra in Joint European Torus (JET) fusion plasma experiments. The spectrometer, based on a liquid scintillation detector (BC501A), is equipped with a Digital Pulse Shape Discrimination (DPSD) acquisition system for neutron (n) and gamma-ray(gamma) separation. The CNS enables recording the n and gamma pulse height spectra (PHS) up to total count rates of similar to 10(6) s(-1). Energy resolution, after PHS unfolding, will be <2% for 14 MeV neutrons and <4% for 2.5 MeV neutrons. The work done by ENEA-Frascati and Physikalisch-Technische Bundesanstalt (PTB) respectively in the assembly and test of DPSD and scintillation detector, along with the first results obtained by the spectrometer in JET plasma experiments are presented. The experience obtained with CNS in JET will contribute to the development of neutron spectrometers suitable for applications in the International Thermonuclear Experimental Reactor (ITER).
|
|
| 3. |
- Eriksson, Jacob, et al.
(författare)
-
Deuterium density profile determination at JET using a neutron camera and a neutronspectrometer
- 2014
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 85:11, s. 11E106-
-
Tidskriftsartikel (refereegranskat)abstract
- In this work we estimate the fuel ion density profile in deuterium plasmas at JET, using the JET neutron camera, the neutron time-of-flight spectrometer TOFOR, and fusion reactivities modeled by the transport code TRANSP. The framework has been tested using synthetic data, which showed that the density profile could be reconstructed with an average accuracy of the order of 10 %. The method has also been applied to neutron measurements from a neutral beam heated JET discharge, which gave nd/ne ≈ 0.6 ± 0.3 in the plasma core and nd/ne ≈ 0.4 ± 0.3 towards the edge. Correction factors for detector efficiencies, neutron attenuation, and back-scattering are not yet included in the analysis; future work will aim at refining the estimated density.
|
|
| 4. |
- Gatu Johnson, Maria, 1978-, et al.
(författare)
-
The TOFOR neutron spectrometer and its first use at JET
- 2006
-
Ingår i: Review of Scientific Instruments. - American Institute of Physics : AIP Publishing. - 0034-6748 .- 1089-7623. ; 77:10E702, s. 1-3
-
Tidskriftsartikel (refereegranskat)abstract
- A time-of-flight neutron spectrometer (TOFOR) has been developed to measure the 2.45 MeV d+d3He+n neutron emission from D plasmas. The TOFOR design features the capability to operate at high rates in the 100 kHz range, data collection with fast time digitizing and storing, and monitoring of the signals from the scintillation detectors used. This article describes the principles of the instrument and its installation at JET and presents preliminary data to illustrate the TOFOR performance as a neutron emission spectroscopy diagnostic.
|
|
| 5. |
|
|
| 6. |
- Giacomelli, Luca, et al.
(författare)
-
Advanced Neutron Diagnostics for JET and ITER Fusion Experiments
- 2005
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 45, s. 1191-1201
-
Tidskriftsartikel (refereegranskat)abstract
- The diagnostics functions of neutron measurements as well as the roles played by neutron yield monitors, cameras and spectrometers are reviewed. The importance of recent developments in neutron emission spectroscopy (NES) diagnostics is emphasized. Results are presented from the NES diagnosis of the Joint European Torus (JET) plasmas performed with the magnetic proton recoil (MPR) spectrometer during the first deuterium tritium experiment of 1997 and the recent trace tritium experiment of 2003. The NES diagnostic capabilities at JET are presently being enhanced by an upgrade of the MPR (MPRu) and a new 2.5 MeV time-of-flight (TOF) neutron spectrometer (TOFOR). The principles of MPRu and TOFOR are described and illustrated with the diagnostic role they will play in the high performance fusion experiments in the forward programme of JET largely aimed at supporting the International Thermonuclear Experimental Reactor (ITER). The importance of the JET NES effort for ITER is discussed.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Giacomelli, Luca, et al.
(författare)
-
Comparison of neutron emission spectra for D and DT plasmas with auxiliary heating
- 2005
-
Ingår i: The European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; :33, s. 235-241
-
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.
|
|
| 10. |
- Giacomelli, Luca, 1973-
(författare)
-
Development of Neutron Emission Spectroscopy Instrumentation for Deuterium and Deuterium-Tritium Fusion Plasmas at JET
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of high power fusion plasmas at the JET tokamak has been further enhanced through the development of instrumentation for neutron emission spectroscopy (NES) measurements. This has involved the upgrade of the magnetic proton recoil (MPR) spectrometer used for deuterium-tritium plasmas earlier so that the MPRu can now be also employed for deuterium (D) plasmas. A neutron time-of-flight (TOF) spectrometer designed for optimized rate (TOFOR) has been constructed and put into operation. The MPRu and TOFOR spectrometers were carried out as part of the JET enhanced performance program and represent the most advanced instrumentation for NES diagnosis of both D and DT tokamak plasmas setting a central platform for R&D direct to the next step in fusion research to be carried out with ITER.The MPRu work presented in this thesis concerns the development of a new focal plane detector based on the phoswich scintillator technique. The main objective of this sub-project was to increase the signal-to-background ratio to permit measurement of the 2.5-MeV neutron emission from d+d-->3He+n reactions and, hence, allow NES diagnosis of D plasmas. The objective was achieved as demonstrated in preliminary measurements at JET.The development of TOFOR from concept to construction is presented in the thesis including, in particular, the commissioning of the instrument at JET. The objective of the TOFOR project was to achieve the same high performance in the NES diagnosis of D plasmas as had earlier been demonstrated by the MPR for DT plasmas. TOFOR has been used in the first plasma physics experiments reported in this thesis. These demonstrate that the performance objectives have been achieved as tested, in particular, in the observation of auxiliary heating effects on velocity distribution of the deuterium population.
|
|
