Self-organisation and intermittent coherent oscillations in the EXTRAP T2 reversed field pinch
2002 (English)In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 65, no 1, 69-75 p.Article in journal (Refereed) Published
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.
LOCKED MODES, MAGNETIC RECONNECTION, NONLINEAR DYNAMICS, RELAXATION, PLASMA, CONFINEMENT, GENERATION, FLUCTUATIONS, MECHANISM, BEHAVIOR
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:kth:diva-13014DOI: 10.1238/Physica.Regular.065a00069ISI: 000173243200009OAI: oai:DiVA.org:kth-13014DiVA: diva2:320204
QC 201005242010-05-242010-05-242012-06-07Bibliographically approved