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Vector dither experiment design and direct parametric identification of reversed-field pinch normal modes
KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. (System Identification Group)ORCID iD: 0000-0002-9368-3079
KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. (System Identification Group)ORCID iD: 0000-0003-0355-2663
KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.ORCID iD: 0000-0002-5259-0458
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2009 (English)In: Proceedings of the IEEE Conference on Decision and Control, 2009, 1348-1353 p.Conference paper, Published paper (Refereed)
Abstract [en]

Magnetic confinement fusion (MCF) research ambitiously endeavours to develop a major future energy source. MCF power plant designs, typically some variation on the tokamak, unfortunately suffer from magnetohydrodynamic (MHD) instabilities. One unstable mode is known as the resistive-wall mode (RWM) which is a macroscopically global type of perturbation that can degrade or even terminate the plasma in the reactor if not stabilized. In this work the topic of RWMs is studied for the reversed-field pinch (RFP), another toroidal MCF concept, similar to the tokamak. The problem of identifying RWM dynamics during closed-loop operation is tackled by letting physics-based parametric modeling join forces with convex programming experiment design. An established MHD normal modes description is assessed for the RFP by synthesizing a multivariable dither signal where spatial fourier modes are spectrally shaped, with regard to real experiment constraints, to yield minimum variance parameter estimates in the prediction-error framework. The dithering is applied to the real RFP plant EXTRAP-T2R, and experimental MHD spectra are obtained by an automated procedure.

Place, publisher, year, edition, pages
2009. 1348-1353 p.
Keyword [en]
Automated procedures, Closed-loop operation, Convex programming, Dither signals, Energy source, Experiment design, Fourier modes
National Category
Control Engineering
Research subject
SRA - ICT
Identifiers
URN: urn:nbn:se:kth:diva-12889DOI: 10.1109/CDC.2009.5400016ISI: 000336893601138Scopus ID: 2-s2.0-77950843926ISBN: 978-142443871-6 (print)OAI: oai:DiVA.org:kth-12889DiVA: diva2:319539
Conference
48th IEEE Conference on Decision and Control held jointly with 2009 28th Chinese Control Conference, CDC/CCC 2009, Shanghai, 15-18 December, 2009
Funder
Swedish Research Council, 621-2005-4345
Note

QC 20100518

Available from: 2010-05-18 Created: 2010-05-18 Last updated: 2015-06-10Bibliographically approved
In thesis
1. Closed-loop control and identification of resistive shell magnetohydrodynamics for the reversed-field pinch
Open this publication in new window or tab >>Closed-loop control and identification of resistive shell magnetohydrodynamics for the reversed-field pinch
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

It is demonstrated that control software updates for the magnetic confinement fusion experiment EXTRAP T2R can enable novel studies of plasma physics. Specifically, it is shown that the boundary radial magnetic field in T2R can be maintained at finite levels by feedback. System identification methods to measure in situ magnetohydrodynamic stability are developed and applied with encouraging results. Subsequently, results from closed-loop identification are used for retooling the T2R regulator. The track of research here pursued could possibly be relevant for future thermonuclear fusion reactors.

Publisher
78 p.
Series
Trita-EE, ISSN 1653-5146 ; 2010:019
National Category
Fusion, Plasma and Space Physics Control Engineering
Identifiers
urn:nbn:se:kth:diva-12794 (URN)978-91-7415-644-7 (ISBN)
Presentation
2010-05-26, E1, KTH, Lindstedtsvägen 3, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100518Available from: 2010-05-18 Created: 2010-05-11 Last updated: 2012-03-21Bibliographically approved
2. Nonaxisymmetric experimental modal analysis and control of resistive wall MHD in RFPs: System identification and feedback control for the reversed-field pinch
Open this publication in new window or tab >>Nonaxisymmetric experimental modal analysis and control of resistive wall MHD in RFPs: System identification and feedback control for the reversed-field pinch
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The reversed-field pinch (RFP) is a device for magnetic confinement of fusion plasmas. The main objective of fusion plasma research is to realise cost-effective thermonuclear fusion power plants. The RFP is highly unstable as can be explained by the theory of magnetohydrodynamics (MHD). Feed-back control technology appears to enable a robustly stable RFP operation.  Experimental control and identification of nonaxisymmetric multimode MHD is pursued in this thesis. It is shown that nonparametric multivariate identification methods can be utilised to estimate MHD spectral characteristics from plant-friendly closed-loop operational input-output data. It is also shown that accurate tracking of the radial magnetic field boundary condition is experimentally possible in the RFP. These results appear generically useful as tools in both control and physics research in magnetic confinement fusion.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. ix, 101 p.
Series
Trita-EES, 2012:20
Keyword
Magnetic confinement fusion, Reversed-field pinch, System identification, Magnetohydrodynamics, Modal analysis, Automatic control, Resistive wall modes
National Category
Fusion, Plasma and Space Physics Control Engineering Signal Processing
Identifiers
urn:nbn:se:kth:diva-94096 (URN)978-91-7501-359-6 (ISBN)
Public defence
2012-06-01, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20120508

Available from: 2012-05-08 Created: 2012-05-07 Last updated: 2013-12-04Bibliographically approved

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Hjalmarsson, HåkanRojas, Cristian R.Brunsell, Per

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Olofsson, K. Erik J.Hjalmarsson, HåkanRojas, Cristian R.Brunsell, PerDrake, James Robert
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