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Fuel ion ratio determination in NBI heated deuterium tritium fusion plasmas at JET using neutron emission spectrometry
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.
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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2015 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 55, no 2, 023005Article in journal (Refereed) Published
Abstract [en]

The fuel ion ratio ( n t / n d ) is of central importance for the performance and control of a future burning fusion plasma, and reliable measurements of this quantity are essential for ITER. This paper demonstrates a method to derive the core fuel ion ratio by comparing the thermonuclear and beam-thermal neutron emission intensities, using a neutron spectrometer. The method is applied to NBI heated deuterium tritium (DT) plasmas at JET, using data from the magnetic proton recoil spectrometer. The trend in the results is consistent with Penning trap measurements of the fuel ion ratio at the edge of the plasma, but there is a discrepancy in the absolute values, possibly owing to the fact that the two measurements are weighted towards different parts of the plasma. It is suggested to further validate this method by comparing it to the traditionally proposed method to estimate n t / n d from the ratio of the thermal DD and DT neutron emission components. The spectrometer requirements for measuring n t / n d at ITER are also briefly discussed.

Place, publisher, year, edition, pages
2015. Vol. 55, no 2, 023005
National Category
Fusion, Plasma and Space Physics
Research subject
Physics
Identifiers
URN: urn:nbn:se:uu:diva-244352DOI: 10.1088/0029-5515/55/2/023005ISI: 000348843100006OAI: oai:DiVA.org:uu-244352DiVA: diva2:788599
Available from: 2015-02-16 Created: 2015-02-16 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Neutron Emission Spectrometry for Fusion Reactor Diagnosis: Method Development and Data Analysis
Open this publication in new window or tab >>Neutron Emission Spectrometry for Fusion Reactor Diagnosis: Method Development and Data Analysis
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

It is possible to obtain information about various properties of the fuel ions deuterium (D) and tritium (T) in a fusion plasma by measuring the neutron emission from the plasma. Neutrons are produced in fusion reactions between the fuel ions, which means that the intensity and energy spectrum of the emitted neutrons are related to the densities and velocity distributions of these ions.

This thesis describes different methods for analyzing data from fusion neutron measurements. The main focus is on neutron spectrometry measurements, using data used collected at the tokamak fusion reactor JET in England. Several neutron spectrometers are installed at JET, including the time-of-flight spectrometer TOFOR and the magnetic proton recoil (MPRu) spectrometer.

Part of the work is concerned with the calculation of neutron spectra from given fuel ion distributions. Most fusion reactions of interest – such as the D + T and D + D reactions – have two particles in the final state, but there are also examples where three particles are produced, e.g. in the T + T reaction. Both two- and three-body reactions are considered in this thesis. A method for including the finite Larmor radii of the fuel ions in the spectrum calculation is also developed. This effect was seen to significantly affect the shape of the measured TOFOR spectrum for a plasma scenario utilizing ion cyclotron resonance heating (ICRH) in combination with neutral beam injection (NBI).

Using the capability to calculate neutron spectra, it is possible to set up different parametric models of the neutron emission for various plasma scenarios. In this thesis, such models are used to estimate the fuel ion density in NBI heated plasmas and the fast D distribution in plasmas with ICRH.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 92 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1244
Keyword
fusion, plasma diagnostics, neutron spectrometry, TOFOR, MPRu, tokamak, JET, fast ions, fuel ion density, relativistic kinematics
National Category
Fusion, Plasma and Space Physics Subatomic Physics
Research subject
Physics with specialization in Applied Nuclear Physics
Identifiers
urn:nbn:se:uu:diva-247994 (URN)978-91-554-9217-5 (ISBN)
Public defence
2015-05-22, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
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Supervisors
Available from: 2015-04-27 Created: 2015-03-25 Last updated: 2015-07-07

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Hellesen, CarlEriksson, JacobBinda, FedericoConroy, SeanEricsson, GöranHjalmarsson, AndersSkiba, MateuszWeiszflog, Matthias

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