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Controlled magnetohydrodynamic mode sustainment in the reversed-field pinch: Theory, design and experiments
KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.ORCID iD: 0000-0002-5259-0458
2009 (English)In: Fusion engineering and design, ISSN 0920-3796, Vol. 84, no 7-11, 1455-1459 p.Article in journal (Refereed) Published
Abstract [en]

A novel control system design for magnetohydrodynamic (MHD) resistive-wall mode (RWM) stabilization is developed from the viewpoint of process control. The engineering approach assumed consists of system identification, selection of feedback interconnections, and subsequently, associated feedback gain tuning. A design for general output tracking is devised, implemented and experimentally verified to be capable of sustaining MHD modes in the reversed-field pinch (RFP) machine EXTRAP-T2R. In principle, by active feedback. the plasma column boundary is forced to 'user-specified' helicities of prescribed amplitudes and phases. Experimental success is mainly attributed to careful identification of local magnetic field diffusion time-constants, and individual actuator channel peripheral dynamics. Addition of functionality and key features of this new MHD feedback system software might provide a versatile tool for experimental plasma dynamics and innovative MHD stability research.

Place, publisher, year, edition, pages
2009. Vol. 84, no 7-11, 1455-1459 p.
Keyword [en]
Fusion plasma physics, Magnetohydrodynamics, Resistive-wall modes, Automatic control, System identification, Process control, INTELLIGENT SHELL, FEEDBACK, STABILIZATION
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-12891DOI: 10.1016/j.fusengdes.2008.11.052ISI: 000268012700078Scopus ID: 2-s2.0-67349189891OAI: oai:DiVA.org:kth-12891DiVA: diva2:319542
Note
QC 20100518Available from: 2010-05-18 Created: 2010-05-18 Last updated: 2012-05-08Bibliographically 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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