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Conroy, Sean
Alternative names
Publications (10 of 164) Show all publications
Binda, F., Ericsson, G., Conroy, S. & Andersson Sundén, E. (2017). Calculation of the profile-dependent neutron backscatter matrix for the JET neutron camera system. Paper presented at 29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC. Fusion engineering and design, 123, 865-868
Open this publication in new window or tab >>Calculation of the profile-dependent neutron backscatter matrix for the JET neutron camera system
2017 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 123, p. 865-868Article in journal (Refereed) Published
Abstract [en]

We investigated the dependence of the backscatter component of the neutron spectrum on the emissivity profile. We did so for the JET neutron camera system, by calculating a profile-dependent backscatter matrix for each of the 19 camera channels using a MCNP model of the JET tokamak. We found that, when using a low minimum energy for the summation of the counts in the neutron pulse height spectrum, the backscatter contribution can depend significantly on the emissivity profile. The maximum variation in the backscatter level was 24% (8.0% when compared to the total emission). This effect needs to be considered when a correction for the backscatter contribution is applied to the measured profile.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keyword
Neutron, Profile monitor, Backscatter, mcnp
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-341822 (URN)10.1016/j.fusengdes.2017.03.124 (DOI)000418992000181 ()
Conference
29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC
Available from: 2018-02-15 Created: 2018-02-15 Last updated: 2018-03-13Bibliographically approved
Cufar, A., Batistoni, P., Conroy, S., Ghani, Z., Lengar, I., Milocco, A., . . . Snoj, L. (2017). Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 847, 199-204
Open this publication in new window or tab >>Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator
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2017 (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. 847, p. 199-204Article in journal (Refereed) Published
Abstract [en]

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keyword
Compact DT neutron generator, MCNP, Modelling
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-320412 (URN)10.1016/j.nima.2016.12.009 (DOI)000394396800027 ()
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-04-19Bibliographically approved
Batistoni, P., Popovichev, S., Conroy, S., Lengar, I., Cufar, A., Abhangi, M., . . . Horton, L. (2017). Calibration of neutron detectors on the Joint European Torus. Review of Scientific Instruments, 88(10), Article ID 103505.
Open this publication in new window or tab >>Calibration of neutron detectors on the Joint European Torus
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2017 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 88, no 10, article id 103505Article in journal (Refereed) Published
Abstract [en]

The present paper describes the findings of the calibration of the neutron yield monitors on the Joint European Torus (JET) performed in 2013 using a Cf-252 source deployed inside the torus by the remote handling system, with particular regard to the calibration of fission chambers which provide the time resolved neutron yield from JET plasmas. The experimental data obtained in toroidal, radial, and vertical scans are presented. These data are first analysed following an analytical approach adopted in the previous neutron calibrations at JET. In this way, a calibration function for the volumetric plasma source is derived which allows us to understand the importance of the different plasma regions and of different spatial profiles of neutron emissivity on fission chamber response. Neutronics analyses have also been performed to calculate the correction factors needed to derive the plasma calibration factors taking into account the different energy spectrum and angular emission distribution of the calibrating (point) Cf-252 source, the discrete positions compared to the plasma volumetric source, and the calibration circumstances. All correction factors are presented and discussed. We discuss also the lessons learnt which are the basis for the on-going 14 MeV neutron calibration at JET and for ITER.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-340954 (URN)10.1063/1.4991780 (DOI)000414174000015 ()29092477 (PubMedID)
Available from: 2018-02-14 Created: 2018-02-14 Last updated: 2018-02-14Bibliographically approved
Binda, F., Eriksson, J., Ericsson, G., Hellesen, C., Conroy, S., Nocente, M. & Andersson Sundén, E. (2017). Generation of the neutron response function of an NE213 scintillator for fusion applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 866, 222-229
Open this publication in new window or tab >>Generation of the neutron response function of an NE213 scintillator for fusion applications
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2017 (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. 866, p. 222-229Article in journal (Refereed) Published
Abstract [en]

In this work we present a method to evaluate the neutron response function of an NE213 liquid scintillator. This method is particularly useful when the proton light yield function of the detector has not been measured, since it is based on a proton light yield function taken from literature, MCNPX simulations, measurements of gammarays from a calibration source and measurements of neutrons from fusion experiments with ohmic plasmas. The inclusion of the latter improves the description of the proton light yield function in the energy range of interest (around 2.46 MeV). We apply this method to an NE213 detector installed at JET, inside the radiation shielding of the magnetic proton recoil (MPRu) spectrometer, and present the results from the calibration along with some examples of application of the response function to perform neutron emission spectroscopy (NES) of fusion plasmas. We also investigate how the choice of the proton light yield function affects the NES analysis, finding that the result does not change significantly. This points to the fact that the method for the evaluation of the neutron response function is robust and gives reliable results.

Keyword
NE213 scintillator, Neutron spectroscopy, Response function, Proton light yield
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-330537 (URN)10.1016/j.nima.2017.04.023 (DOI)000407863700029 ()
Available from: 2017-10-04 Created: 2017-10-04 Last updated: 2018-04-23Bibliographically approved
Cecconello, M., Conroy, S., Marocco, D., Moro, F. & Esposito, B. (2017). Neural network implementation for ITER neutron emissivity profile recognition. Paper presented at 29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC. Fusion engineering and design, 123, 637-640
Open this publication in new window or tab >>Neural network implementation for ITER neutron emissivity profile recognition
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2017 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 123, p. 637-640Article in journal (Refereed) Published
Abstract [en]

The ITER Radial Neutron Camera (RNC) is a neutron diagnostic intended for the measurement of the neutron emissivity radial profile and the estimate of the total fusion power. This paper presents a proof of-principle method based on neural networks to estimate the neutron emissivity profile in different ITER scenarios and for different RNC architectures. The design, optimization and training of the implemented neural network is presented together with a decision algorithm to select, among the multiple trained neural networks, which one provides the inverted neutron emissivity profile closest to the input one. Examples are given for a selection of ITER scenarios and RNC architectures. The results from this study indicate that neural networks for the neutron emissivity recognition in ITER can achieve an accuracy and precision within the spatial and temporal requirements set by ITER for such a diagnostic.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keyword
ITER, RNC, Neural network, Real time, Fusion power
National Category
Subatomic Physics
Identifiers
urn:nbn:se:uu:diva-341820 (URN)10.1016/j.fusengdes.2017.02.058 (DOI)000418992000132 ()
Conference
29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC
Funder
Swedish Research Council, VR 826-2012-5116
Available from: 2018-02-15 Created: 2018-02-15 Last updated: 2018-02-15Bibliographically approved
Moro, F., Marocco, D., Esposito, B., Flammini, D., Podda, S., Villari, R. & Conroy, S. (2017). Nuclear analysis of the ITER radial neutron camera architectural options. Paper presented at 29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC. Fusion engineering and design, 123, 1033-1038
Open this publication in new window or tab >>Nuclear analysis of the ITER radial neutron camera architectural options
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2017 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 123, p. 1033-1038Article in journal (Refereed) Published
Abstract [en]

The ITER Radial Neutron Camera (RNC) is a multichannel detection system hosted in the Equatorial Port Plug 1 (EPP 1) designed to provide information on the neutron source total strength arid emissivity profiles. It consists of two sub-systems: the ex-port line-of-sights (LOSs), covering the plasma core, embedded in a massive shielding block located in the Port Interspace, and the in-port LOSs distributed in two removable cassettes integrated inside the Port Plug. Presently, the RNC layout development process is undergoing a System Level Design phase: several preliminary architectural options based on a System Engineering work have been defined: a detailed nuclear analysis of these options has been performed through radiation transport calculations with the MCNP Monte Carlo code. The radiation environment at the detectors positions has been fully characterized through the evaluation of the expected neutron spectra and the secondary gamma background and the analysis of the 3D radiation maps. MoreOver, the impact of a reduced ex-port shielding block on the neutron and gamma spectra has been investigated. The results of the present study provide guidelines for the development of the RNC final design and the necessary data for the measurement performance analysis.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keyword
ITER, Radial neutron camera, Neutronics, Equatorial port plug, Design, Analysis
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-341824 (URN)10.1016/j.fusengdes.2017.01.031 (DOI)000418992000217 ()
Conference
29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC
Available from: 2018-02-16 Created: 2018-02-16 Last updated: 2018-02-16Bibliographically 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
Keyword
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
Sjöstrand, H., Conroy, S., Helgesson, P., Hernandez Solis, A., Koning, A., Pomp, S. & Rochman, D. (2017). Propagation of nuclear data uncertainties for fusion power measurements. Paper presented at ND2016. EPJ Web of Conferences, 146(02034)
Open this publication in new window or tab >>Propagation of nuclear data uncertainties for fusion power measurements
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2017 (English)In: EPJ Web of Conferences, Vol. 146, no 02034Article in journal (Refereed) Published
Abstract [en]

Abstract. Neutron measurements using neutron activation systems are an essential part of the diagnostic system at large fusion machines such as JET and ITER. Nuclear data is used to infer the neutron yield.Consequently, high-quality nuclear data is essential for the proper determination of the neutron yield and fusion power. However, uncertainties due to nuclear data are not fully taken into account in uncertainty analysis for neutron yield calibrations using activation foils. This paper investigates the neutron yield uncertainty due to nuclear data using the so-called Total Monte Carlo Method. The work is performed using a detailed MCNP model of the JET fusion machine; the uncertainties due to the cross-sections and angular distributions in JET structural materials, as well as the activation cross-sections in the activation foils, are analyzed. It is found that a significant contribution to the neutron yield uncertainty can come from uncertainties in the nuclear data.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-343958 (URN)10.1051/epjconf/201714602034 (DOI)
Conference
ND2016
Available from: 2018-03-02 Created: 2018-03-02 Last updated: 2018-03-07Bibliographically approved
Huber, A., Sergienko, G., Kinna, D., Huber, V., Milocco, A., Mercadier, L., . . . Zastrow, K.-D. (2017). Response of the imaging cameras to hard radiation during JET operation. Paper presented at 29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC. Fusion engineering and design, 123, 669-673
Open this publication in new window or tab >>Response of the imaging cameras to hard radiation during JET operation
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2017 (English)In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 123, p. 669-673Article in journal (Refereed) Published
Abstract [en]

The analysis of the radiation damage of imaging systems is based on all different types-of aiialoiue/digital cameras with uncooled as well as actively cooled image sensors in the VIS/NIR/MWIR spectral ranges. The Monte Carlo N-Particle (MCNP) code has been used to determine the neutron fluence at different camera locations in JET. An explicit link between the sensor damage and the neutron fluence has been observed. Sensors show an increased dark-current and increased numbers of hot-pixels. Uncooled cameras must be replaced once per year after exposure to a neutron fluence of similar to 1.9-3.2 x 10(12)neutrons/cm(2). Such levels of fluence will be reached after approximate to 14-22 ELMy H-mode pulses during the future D-T campaign. Furthermore, dynamical noise seen as a random pattern of bright pixels was observed in the presence of hard radiation (neutrons and gammas). Failure of the digital electronics inside the cameras as well as of industrial controllers is observed beyond a neutron fluence of about similar to 4 x 10(9) neutrons/cm(2). The impact of hard radiation on the different types of electronics and possible application of cameras during future D-T campaign is discussed.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keyword
CCd, Camera, Radiation damage, Hot pixels, Image, Camera cooling
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-341821 (URN)10.1016/j.fusengdes.2017.03.167 (DOI)000418992000139 ()
Conference
29th Symposium on Fusion Technology (SOFT), SEP 05-09, 2016, Prague, CZECH REPUBLIC
Available from: 2018-02-15 Created: 2018-02-15 Last updated: 2018-02-15Bibliographically approved
Weisen, H., Kim, H.-T., Strachan, J., Scott, S., Baranov, Y., Buchanan, J., . . . Santala, M. (2017). The 'neutron deficit' in the JET tokamak. Nuclear Fusion, 57(7), Article ID 076029.
Open this publication in new window or tab >>The 'neutron deficit' in the JET tokamak
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2017 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 57, no 7, article id 076029Article in journal (Refereed) Published
Abstract [en]

The measured D-D neutron rate of neutral beam heated JET baseline and hybrid H-modes in deuterium is found to be between approximately 50% and 100% of the neutron rate expected from the TRANSP code, depending on the plasma parameters. A number of candidate explanations for the shortfall, such as fuel dilution, errors in beam penetration and effectively available beam power have been excluded. As the neutron rate in JET is dominated by beamplasma interactions, the ` neutron deficit' may be caused by a yet unidentified form of fast particle redistribution. Modelling, which assumes fast particle transport to be responsible for the deficit, indicates that such redistribution would have to happen at time scales faster than both the slowing down time and the energy confinement time. Sawteeth and edge localised modes are found to make no significant contribution to the deficit. There is also no obvious correlation with magnetohydrodynamic activity measured using magnetic probes at the tokamak vessel walls. Modelling of fast particle orbits in the 3D fields of neoclassical tearing modes shows that realistically sized islands can only contribute a few percent to the deficit. In view of these results it appears unlikely that the neutron deficit results from a single physical process in the plasma.

Keyword
neutron yield, fusion reactions, Monte Carlo orbit code, TRANSP
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:uu:diva-327364 (URN)10.1088/1741-4326/aa6dcc (DOI)000402878400004 ()
Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2017-08-21Bibliographically approved
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