Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Self-organisation and intermittent coherent oscillations in the EXTRAP T2 reversed field pinch
KTH, Superseded Departments, Alfvén Laboratory.
KTH, Superseded Departments, Alfvén Laboratory.
KTH, Superseded Departments, Alfvén Laboratory.
KTH, Superseded Departments, Alfvén Laboratory.
2002 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 65, no 1, 69-75 p.Article in journal (Refereed) Published
Abstract [en]

Many reversed-field pinch (RFP) experiments exhibit a coherent oscillatory behaviour that is characteristic of discrete dynamo events and is associated with intermittent current profile self-organisation phenomena. However, in the vast majority of the discharges in the resistive shell RFP experiment EXTRAP T2, the dynamo activity does not show global, coherent oscillatory behaviour, The internally resonant tearing modes are phase-aligned and wall-locked resulting in a large localised magnetic perturbation. Equilibrium and plasma parameters have a level of high frequency fluctuations but the average values are quasi-steady. For some discharges, however, the equilibrium parameters exhibit the oscillatory behaviour characteristic of the discrete dynamo events. For these discharges, the trend observed in the tearing mode spectra, associated with the onset of the discrete relaxation event behaviour, is a relative higher amplitude of m = 0 mode activity and relative lower amplitude of the m = 1 mode activity compared with their average values. Global plasma parameters and model profile calculations for sample discharges representing the two types of relaxation dynamics are presented.

Place, publisher, year, edition, pages
Stockholm: ROYAL SWEDISH ACAD SCIENCES , 2002. Vol. 65, no 1, 69-75 p.
Keyword [en]
LOCKED MODES, MAGNETIC RECONNECTION, NONLINEAR DYNAMICS, RELAXATION, PLASMA, CONFINEMENT, GENERATION, FLUCTUATIONS, MECHANISM, BEHAVIOR
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-13014DOI: 10.1238/Physica.Regular.065a00069ISI: 000173243200009OAI: oai:DiVA.org:kth-13014DiVA: diva2:320204
Note
QC 20100524Available from: 2010-05-24 Created: 2010-05-24 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Experimental studies of confinement in the EXTRAP T2 and T2R reversed field pinches
Open this publication in new window or tab >>Experimental studies of confinement in the EXTRAP T2 and T2R reversed field pinches
2003 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The confinement properties of fusion plasmas are affected bymagnetic and electrostatic fluctuations. The determination ofthe plasma confinement properties requires the measurement ofseveral global and local quantities such as the ion andelectron temperatures, the electron and neutral densityprofiles, the radiation emissivity profiles, the ohmic inputpower and the particle and heat diffusivities. The focus ofthis thesis is the study of the plasma confinement propertiesbased on measurements of these quantities under differentexperimental conditions.

The studies have been carried out on the reversed fieldpinch experiments EXTRAP T2 and T2R at the AlfvénLaboratory, Royal Institute of Technology (KTH) in Stockholm.Studies carried out in EXTRAP T2 were focused on dynamoactivity and on the effect of phase alignment and locking tothe wall of magnetic instabilities. These were observed with adedicated imaging system. The experimental studies in EXTRAPT2R were focused on the measurement of the confinementproperties of different configurations. To this aim, a set ofdiagnostics were used some of which were upgraded, such as theinterferometer, while others were newly installed, such as aneutral particle energy analyser and a bolometer array.

The dynamo, which is responsible for the plasma sustainment,involves resistive magnetohydrodynamic instabilities thatenhance stochastic transport. Furthermore, the plasmaconfinement properties are in general improved in the presenceof mode rotation. The possibility of reducing the stochastictransport and thereby further improving the confinement hasbeen demonstrated in a current profile control experiment.These results indicate that long pulse operations with aresisitive shell and current profile control are indeedfeasible.

KeywordsEXTRAP T2, T2R, reversed field pinch, dynamo,energy confinement time, transport, CCD, bolometer,interferometer, neutral particle energy analyser, PPCD, MonteCarlo

Place, publisher, year, edition, pages
Stockholm: KTH, 2003. x, 135 p.
Keyword
extap t2, extrap t2r, reversed field pinch
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-3468 (URN)91-7283-417-X (ISBN)
Public defence
2003-01-31, 00:00 (English)
Note
QC 20100524Available from: 2003-02-06 Created: 2003-02-06 Last updated: 2010-05-24Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Cecconello, MarcoMalmberg, Jenny-AnnSallander, EvaDrake, Drake James
By organisation
Alfvén Laboratory
In the same journal
Physica Scripta
Atom and Molecular Physics and Optics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 63 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf