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Determination of hydrogen/deuterium ratio with neutron measurements on MAST
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
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2014 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 11, 11E109- p.Article in journal (Refereed) Published
Abstract [en]

On MAST, compressional Alfven eigenmodes can be destabilized by the presence of a sufficiently large population of energetic particles in the plasma. This dependence was studied in a series of very similar discharges in which increasing amounts of hydrogen were puffed into a deuterium plasma. A simple method to estimate the isotopic ratio n(H)/n(D) using neutron emission measurements is here described. The inferred isotopic ratio ranged from 0.0 to 0.6 and no experimental indication of changes in radial profile of n(H)/n(D) were observed. These findings are confirmed by TRANSP/NUBEAM simulations of the neutron emission.

Place, publisher, year, edition, pages
2014. Vol. 85, no 11, 11E109- p.
National Category
Physical Sciences
URN: urn:nbn:se:uu:diva-240140DOI: 10.1063/1.4889910ISI: 000345646000129PubMedID: 25430288OAI: oai:DiVA.org:uu-240140DiVA: diva2:776637
Available from: 2015-01-07 Created: 2015-01-05 Last updated: 2016-05-12Bibliographically approved
In thesis
1. Modelling and Measurements of MAST Neutron Emission
Open this publication in new window or tab >>Modelling and Measurements of MAST Neutron Emission
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Measurements of neutron emission from a fusion plasma can provide a wealth of information on the underlying temporal, spatial and energy distributions of reacting ions and how they are affected by a wide range of magneto-hydro-dynamic (MHD) instabilities.

This thesis focuses on the interpretation of the experimental measurements recorded by neutron flux monitors with and without spectroscopic capabilities installed on the Mega Ampere Spherical Tokamak (MAST). In particular, the temporally and spatially resolved measurements of the neutron rate measured by the neutron camera, which also possesses spectroscopic capabilities, are combined with the temporally resolved measurements of the total neutron rate provided by the absolutely calibrated fission chamber in order to study the properties of the fast ion distributions in different plasma scenarios.

The first part of the thesis describes in detail the two forward modelling methods, which employ the set of interconnected codes developed to interpret experimental observations such as neutron count rate profiles and recoil proton pulse height spectra provided by the neutron camera. In the second part of the thesis the developed methods are applied to model the neutron camera observations performed in a variety of plasma scenarios. The first method, which involves only TRANSP/NUBEAM and LINE2 codes, was used to validate the neutron count rate profiles measured by the neutron camera in three different plasma scenarios covering the wide range of total neutron rate typically observed on MAST. In addition, the first framework was applied to model the changes in the total and local neutron rates caused by fishbone instability as well as to estimate the Hydrogen and Deuterium ion ratio. The second modelling method, which involves TRANSP/NUBEAM, LINE2, DRESS and NRESP, was used to validate the measured recoil proton pulse height spectra in a MHD-quiescent plasma scenario.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 75 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1364
fusion, plasma diagnostics, neutron emissivity and rate, Neutron Camera, tokamak, MAST
National Category
Fusion, Plasma and Space Physics
Research subject
Physics with specialization in Applied Nuclear Physics
urn:nbn:se:uu:diva-282122 (URN)978-91-554-9541-1 (ISBN)
Public defence
2016-05-26, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2016-05-04 Created: 2016-04-02 Last updated: 2016-05-12

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Klimek, IwonaCecconello, MarcoEricsson, Göran
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