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Hjalmarsson, Anders
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Publications (10 of 76) Show all publications
Riva, M., Esposito, B., Marocco, D., Cecconello, M., Kotula, J., Moro, F., . . . Brichard, B. (2018). High-Priority Prototype Testing in Support of System-Level Design Development of the ITER Radial Neutron Camera. IEEE Transactions on Plasma Science, 46(5), 1291-1297
Open this publication in new window or tab >>High-Priority Prototype Testing in Support of System-Level Design Development of the ITER Radial Neutron Camera
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2018 (English)In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 46, no 5, p. 1291-1297Article in journal (Refereed) Published
Abstract [en]

This paper describes the high-priority testing activities supporting the ITER radial neutron camera (RNC) design, performed by a consortium of European institutes within a framework contract placed by fusion for energy, the ITER European Domestic Agency. The main role of the RNC is to measure the uncollided 14- and 2.5-MeV neutrons from deuterium-tritium and deuterium-deuterium fusion reactions through an array of flux monitors/spectrometers located in collimated lines of sight viewing the plasma through the ITER equatorial port plug #1. The line-integrated neutron fluxes will be used to evaluate, through reconstruction techniques, the radial profile of the neutrons emitted per unit time and volume (neutron emissivity) and, therefore, the neutron yield and the alpha particles' birth profile. The activity of high-priority testing is dedicated to the preparation and the design of experimental test environment, the conduction of appropriate tests and reporting of test results for the high-priority prototypes, clarifying or verifying the expected key function and system behavior, and enhancing learning on specific issues (potential showstoppers).

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
Detectors, field-programmable gate array (FPGA), ITER, neutronics, real time
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-356402 (URN)10.1109/TPS.2018.2795647 (DOI)000431521700034 ()
Available from: 2018-07-25 Created: 2018-07-25 Last updated: 2018-07-25Bibliographically approved
Mattera, A., Pomp, S., Lantz, M., Rakopoulos, V., Solders, A., Al-Adili, A., . . . Eronen, T. (2017). A neutron source for IGISOL-JYFLTRAP: Design and characterisation. European Physical Journal A, 53(173)
Open this publication in new window or tab >>A neutron source for IGISOL-JYFLTRAP: Design and characterisation
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2017 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 53, no 173Article in journal (Refereed) Published
Abstract [en]

A white neutron source based on the Be(p,nx) reaction for fission studies at the IGISOLJYFLTRAP facility has been designed and tested. 30 MeV protons impinge on a 5mm thick water-cooled beryllium disc. The source was designed to produce at least 1012 fast neutrons/s on a secondary fission target, in order to reach competitive production rates of fission products far from the valley of stability.

The Monte Carlo codes MCNPX and FLUKA were used in the design phase to simulate the neutron energy spectra. Two experiments to characterise the neutron field were performed: the first was carried out at The Svedberg Laboratory in Uppsala (SE), using an Extended-Range Bonner Sphere Spectrometer and a liquid scintillator which used the time-of-flight (TOF) method to determine the energy of the neutrons; the second employed Thin-Film Breakdown Counters for the measurement of the TOF, and activation foils, at the IGISOL facility in Jyväskylä (FI). Design considerations and the results of the two characterisation measurements are presented, providing benchmarks for the simulations.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-328569 (URN)10.1140/epja/i2017-12362-x (DOI)000408661200001 ()
Funder
Swedish Radiation Safety AuthoritySwedish Nuclear Fuel and Waste Management Company, SKB
Available from: 2017-08-26 Created: 2017-08-26 Last updated: 2017-12-01Bibliographically approved
Hellesen, C., Andersson Sundén, E., Conroy, S., Dzysiuk, N., Ericsson, G., Hjalmarsson, A., . . . Marcinkevicius, B. (2017). Conceptual design of a BackTOF neutron spectrometer for fuel ion ratio measurements at ITER. Nuclear Fusion, 57(6), Article ID 066021.
Open this publication in new window or tab >>Conceptual design of a BackTOF neutron spectrometer for fuel ion ratio measurements at ITER
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2017 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 6, article id 066021Article in journal (Refereed) Published
Abstract [en]

In this paper we present a conceptual design of a back scattering neutron time of flight spectrometer (BackTOF) for use at ITER. The proposed BackTOF design aims at fulfilling the requirements set on a neutron spectrometer system to be used for inferring the core fuel ion ratio in a DT plasma. Specifically we have investigated the requirements on the size, energy resolution, count rate capability, efficiency and signal to background ratio. These requirements are a compact size that fits in roughly 1 m3, an energy resolution of 4% or better, a count rate capability of at least 100 kHz, an efficiency of at least 10−5 and a signal to background ratio of 1000 or better.

Using a Monte Carlo model of the BackTOF spectrometer we find that the proposed BackTOF design is compact enough to be installed at ITER while being capable of achieving a resolution of about 4% FWHM with a count rate capability of 300 kHz and an efficiency at 1.25 10−3. This is sufficient for achieving the requirements on the fuel ion ratio at ITER. We also demonstrate how data acquisition systems capable of providing both timing and energy information can be used to effectively discriminate random background at high count rates.

Keywords
neutron spectroscopy, time of flight, burning plasma, fuel ion ratio
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-348803 (URN)10.1088/1741-4326/aa6937 (DOI)000425870000001 ()
Available from: 2018-05-04 Created: 2018-05-04 Last updated: 2018-05-04Bibliographically approved
Kazakov, Y. O. O., Possnert, G., Sjöstrand, H., Skiba, M., Weiszflog, M., Andersson Sundén, E., . . . Kazantzidis, V. (2017). Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating. Nature Physics, 13(10), 973-978
Open this publication in new window or tab >>Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating
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2017 (English)In: Nature Physics, ISSN 1745-2473, E-ISSN 1745-2481, Vol. 13, no 10, p. 973-978Article in journal (Refereed) Published
Abstract [en]

We describe a new technique for the efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed three-ion scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of the method on the world-largest plasma magnetic confinement device, JET (Joint European Torus, Culham, UK), and the high-magnetic-field tokamak Alcator C-Mod (Cambridge, USA). The obtained results demonstrate efficient acceleration of He-3 ions to high energies in dedicated hydrogendeuterium mixtures. Simultaneously, effective plasma heating is observed, as a result of the slowing-down of the fast He-3 ions. The developed technique is not only limited to laboratory plasmas, but can also be applied to explain observations of energetic ions in space-plasma environments, in particular, He-3-rich solar flares.

National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-359272 (URN)10.1038/NPHYS4167 (DOI)000412181200018 ()
Note

For a complete list of authors see http://dx.doi.org/10.1038/NPHYS4167

Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-05Bibliographically approved
Salewski, M., Nocente, M., Jacobsen, A. S., Binda, F., Cazzaniga, C., Ericsson, G., . . . Tardocchi, M. (2017). MeV-range velocity-space tomography from gamma-ray and neutron emission spectrometry measurements at JET. Nuclear Fusion, 57(5), Article ID 056001.
Open this publication in new window or tab >>MeV-range velocity-space tomography from gamma-ray and neutron emission spectrometry measurements at JET
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2017 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 5, article id 056001Article in journal (Refereed) Published
Abstract [en]

We demonstrate the measurement of a 2D MeV-range ion velocity distribution function by velocity-space tomography at JET. Deuterium ions were accelerated into the MeV-range by third harmonic ion cyclotron resonance heating. We made measurements with three neutron emission spectrometers and a high-resolution gamma-ray spectrometer detecting the gamma-rays released in two reactions. The tomographic inversion based on these five spectra is in excellent agreement with numerical simulations with the ASCOT-RFOF and the SPOT-RFOF codes. The length of the measured fast-ion tail corroborates the prediction that very few particles are accelerated above 2 MeV due to the weak wave-particle interaction at higher energies.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
gamma-ray spectrometry, neutron emission spectrometry, velocity-space tomography, fast ions, tokamak
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-321793 (URN)10.1088/1741-4326/aa60e9 (DOI)000398746700001 ()
Available from: 2017-05-11 Created: 2017-05-11 Last updated: 2018-04-23Bibliographically approved
Litaudon, X., Abduallev, S., Abhangi, M., Abreu, P., Afzal, M., Aggarwal, K. M., . . . Zychor, I. (2017). Overview of the JET results in support to ITER. Nuclear Fusion, 57(10), Article ID 102001.
Open this publication in new window or tab >>Overview of the JET results in support to ITER
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2017 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 10, article id 102001Article in journal (Refereed) Published
Abstract [en]

The 2014-2016 JET results are reviewed in the light of their significance for optimising the ITER research plan for the active and non-active operation. More than 60 h of plasma operation with ITER first wall materials successfully took place since its installation in 2011. New multi-machine scaling of the type I-ELM divertor energy flux density to ITER is supported by first principle modelling. ITER relevant disruption experiments and first principle modelling are reported with a set of three disruption mitigation valves mimicking the ITER setup. Insights of the L-H power threshold in Deuterium and Hydrogen are given, stressing the importance of the magnetic configurations and the recent measurements of fine-scale structures in the edge radial electric. Dimensionless scans of the core and pedestal confinement provide new information to elucidate the importance of the first wall material on the fusion performance. H-mode plasmas at ITER triangularity (H = 1 at beta(N) similar to 1.8 and n/n(GW) similar to 0.6) have been sustained at 2 MA during 5 s. The ITER neutronics codes have been validated on high performance experiments. Prospects for the coming D-T campaign and 14 MeV neutron calibration strategy are reviewed.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
JET, plasma, fusion, ITER
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-340063 (URN)10.1088/1741-4326/aa5e28 (DOI)000416419100001 ()
Available from: 2018-01-25 Created: 2018-01-25 Last updated: 2018-04-23Bibliographically approved
Jacobsen, A. S., Binda, F., Cazzaniga, C., Eriksson, J., Hjalmarsson, A., Nocente, M., . . . Tardini, G. (2017). Velocity-space sensitivities of neutron emission spectrometers at the tokamaks JET and ASDEX Upgrade in deuterium plasmas. Review of Scientific Instruments, 88(7), Article ID 073506.
Open this publication in new window or tab >>Velocity-space sensitivities of neutron emission spectrometers at the tokamaks JET and ASDEX Upgrade in deuterium plasmas
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2017 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, no 7, article id 073506Article in journal (Refereed) Published
Abstract [en]

Future fusion reactors are foreseen to be heated by the energetic alpha particles produced in fusion reactions. For this to happen, it is important that the energetic ions are sufficiently confined. In present day fusion experiments, energetic ions are primarily produced using external heating systems such as neutral beam injection and ion cyclotron resonance heating. In order to diagnose these fast ions, several different fast-ion diagnostics have been developed and implemented in the various experiments around the world. The velocity-space sensitivities of fast-ion diagnostics are given by so-called weight functions. Here instrument-specific weight functions are derived for neutron emission spectrometry detectors at the tokamaks JET and ASDEX Upgrade for the 2.45 MeV neutrons produced in deuterium-deuterium reactions in deuterium plasmas. Using these, it is possible to directly determine which part of velocity space each detector observes.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-333408 (URN)10.1063/1.4991651 (DOI)000406773700017 ()28764505 (PubMedID)
Available from: 2017-11-15 Created: 2017-11-15 Last updated: 2018-04-23Bibliographically approved
Sharapov, S. E., Hellsten, T., Kiptily, V. G., Craciunescu, T., Eriksson, J., Fitzgerald, M., . . . Zoita, V. (2016). Fusion product studies via fast ion D-D and D-He-3 fusion on JET. Paper presented at 14th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems, 2015, Vienna, AUSTRIA. Nuclear Fusion, 56(11), Article ID 112021.
Open this publication in new window or tab >>Fusion product studies via fast ion D-D and D-He-3 fusion on JET
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2016 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 56, no 11, article id 112021Article in journal (Refereed) Published
Abstract [en]

Dedicated fast ion D-D and D-He-3 fusion experiments were performed on JET with carbon wall (2008) and ITER-like wall (2014) for testing the upgraded neutron and energetic ion diagnostics of fusion products. Energy spectrum of D-D neutrons was the focus of the studies in pure deuterium plasmas. A significant broadening of the energy spectrum of neutrons born in D-D fast fusion was observed, and dependence of the maximum D and D-D neutron energies on plasma density was established. Diagnostics of charged products of aneutronic D-He-3 fusion reactions, 3.7 MeV alpha-particles similar to those in D-T fusion, and 14.6 MeV protons, were the focus of the studies in D-He-3 plasmas. Measurements of 16.4 MeV gamma-rays born in the weak secondary branch of D(He-3, gamma)Li-5 reaction were used for assessing D-He-3 fusion power. For achieving high yield of D-D and D-He-3 reactions at relatively low levels of input heating power, an acceleration of D beam up to the MeV energy range was used employing 3rd harmonic (f = 3f(CD)) ICRH technique. These results were compared to the techniques of D beam injection into D-He-3 mixture, and He-3-minority ICRH in D plasmas.

Keywords
fusion, neutrons, ICRH, NBI, JET, Deuterium, Helium-3
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-315095 (URN)10.1088/0029-5515/56/11/112021 (DOI)000391393900021 ()
Conference
14th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems, 2015, Vienna, AUSTRIA
Available from: 2017-02-08 Created: 2017-02-08 Last updated: 2018-04-23Bibliographically approved
Skiba, M., Ericsson, G., Hjalmarsson, A., Hellesen, C., Conroy, S., Andersson Sundén, E. & Eriksson, J. (2016). Kinematic Background Discrimination Methods Using a Fully Digital Data Acquisition System for TOFOR. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 838, 82-88
Open this publication in new window or tab >>Kinematic Background Discrimination Methods Using a Fully Digital Data Acquisition System for TOFOR
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2016 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 838, p. 82-88Article in journal (Other academic) Published
Abstract [en]

A fully digital, prototype data acquisition system upgrade for the TOFOR neutron time-of-flight neutron spectrometer at the JET experimental fusion reactor in Culham, England, has been constructed. This upgrade, TOFu (Time-of-Flight upgrade), enables digitization of associated time and energy deposition information from the TOFOR scintillator detectors, facilitating discrimination of spectral background due to unrelated neutron events based on kinematic considerations. In this publication, a kinematic background discrimination method is presented using synthetic data and validated with experimental results. It is found that an improvement in signal-to-background ratio of 500% in certain spectral regions is possible with the new DAQ system.

Keywords
Fusion; Time-of-flight spectrometry; JET; Neutron spectrometry; TOFOR; Data acquisition
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-304381 (URN)10.1016/j.nima.2016.09.030 (DOI)000386061200013 ()
Available from: 2016-10-04 Created: 2016-10-04 Last updated: 2018-04-23Bibliographically approved
Cazzaniga, C., Cremona, A., Nocente, M., Rebai, M., Rigamonti, D., Tardocchi, M., . . . Gorini, G. (2016). Light response of YAP:Ce and LaBr3:Ce scintillators to 4-30 MeV protons for applications to Telescope Proton Recoil neutron spectrometers. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 820, 85-88
Open this publication in new window or tab >>Light response of YAP:Ce and LaBr3:Ce scintillators to 4-30 MeV protons for applications to Telescope Proton Recoil neutron spectrometers
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2016 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 820, p. 85-88Article in journal (Refereed) Published
Abstract [en]

The light response of two thin inorganic scintillators based on YAP:Ce and LaBr3:Ce crystals has been measured with protons in the 4-8 MeV energy range at the Uppsala tandem accelerator and in the 826 MeV energy range at the Legnaro tandem accelerator. The crystals have been calibrated in situ with Cs-137 and Co-60 gamma-ray sources. The relative light yields of protons with respect to gammas have been measured and are here reported to be (96 +/- 2)% and (80 +/- 2)% for YAP:Ce and LaBr3:Ce, respectively. The results open up to the development of a Telescope Proton Recoil spectrometer based on either of the two crystals as alternative to a silicon based spectrometer for applications to high neutron fluxes.

National Category
Subatomic Physics
Research subject
Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-291508 (URN)10.1016/j.nima.2016.03.026 (DOI)000373189200012 ()
Available from: 2016-05-03 Created: 2016-05-03 Last updated: 2017-11-30Bibliographically approved
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