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A parametric model for fusion neutron emissivity tomography for the KN3 neutron camera at JET
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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2010 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 50, no 3, 035008- p.Article in journal (Refereed) Published
Abstract [en]

A parametric model for fusion neutron emissivity is presented and applied to the KN3 neutron camera data collected during the trace tritium experiment at the Joint European Torus. This work is aimed at achieving a good compromise between accuracy of tomographic reconstruction and low model complexity. This means low numerical degeneracy and good time consistency of the results. The model is compared both with plasma simulation codes and other tomographic techniques, which use KN3 line integrated emissivity data, showing good agreement over the entire data set analysed approximate to‰ˆ 500 plasma discharges).

Place, publisher, year, edition, pages
2010. Vol. 50, no 3, 035008- p.
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-129635DOI: 10.1088/0029-5515/50/3/035008ISI: 000275619700022OAI: oai:DiVA.org:uu-129635DiVA: diva2:344645
Available from: 2010-08-19 Created: 2010-08-19 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Neural Networks Applications and Electronics Development for Nuclear Fusion Neutron Diagnostics
Open this publication in new window or tab >>Neural Networks Applications and Electronics Development for Nuclear Fusion Neutron Diagnostics
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the development of electronic modules for fusion neutron spectroscopy as well as several implementations of artificial neural networks (NN) for neutron diagnostics for the Joint European Torus (JET) experimental reactor in England.

The electronics projects include the development of two fast light pulser modules based on Light Emitting Diodes (LEDs) for the calibration and stability monitoring of two neutron spectrometers (MPRu and TOFOR) at JET. The particular electronic implementation of the pulsers allowed for operation of the LEDs in the nanosecond time scale, which is typically not well accessible with simpler circuits. Another electronic project consisted of the the development and implementation at JET of 32 high frequency analog signal amplifiers for MPRu. The circuit board layout adopted and the choice of components permitted to achieve bandwidth above 0.5 GHz and low distortion for a wide range of input signals. The successful and continued use of all electronic modules since 2005 until the present day is an indication of their good performance and reliability.

The NN applications include pulse shape discrimination (PSD), deconvolution of experimental data and tomographic reconstruction of neutron emissivity profiles for JET. The first study showed that NN can perform neutron/gamma PSD in liquid scintillators significantly better than other conventional techniques, especially for low deposited energy in the detector. The second study demonstrated that NN can be used for statistically efficient deconvolution of neutron energy spectra, with and without parametric neutron spectroscopic models, especially in the region of low counts in the data. The work on tomography provided a simple but effective parametric model for describing neutron emissivity at JET. This was then successfully implemented with NN for fast and automatic tomographic reconstruction of the JET camera data.

The fast execution time of NN, i.e. usually in the microsecond time scale, makes the NN applications presented here suitable for real-time data analysis and typically orders of magnitudes faster than other commonly used codes. The results and numerical methods described in this thesis can be applied to other diagnostic instruments and are of relevance for future fusion reactors such as ITER, currently under construction in Cadarache, France.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 126 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 673
Keyword
Neural networks, tomography, unfolding, real time, pulse shape discrimination, PSD, neutron spectroscopy, MPRu, TOFOR, KN3, neutron camera, LED, summing amplifiers, electronics, JET
National Category
Fusion, Plasma and Space Physics Other Physics Topics
Research subject
Applied Nuclear Physics; Electronics
Identifiers
urn:nbn:se:uu:diva-108583 (URN)978-91-554-7613-7 (ISBN)
Public defence
2009-11-06, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1 Polacksbacken, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2009-11-02 Created: 2009-09-23 Last updated: 2013-08-01Bibliographically approved

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