Mode- and plasma rotation in a resistive shell reversed-field pinch
2004 (English)In: Physics of Plasmas, ISSN 1070-664X, Vol. 11, no 2, 647-658 p.Article in journal (Refereed) Published
Mode rotation studies in a resistive shell reversed-field pinch, EXTRAP T2R [P. R. Brunsell , Plasma Phys. Control. Fusion 43, 1 (2001)] are presented. The phase relations and nonlinear coupling of the resonant modes are characterized and compared with that expected from modeling based on the hypothesis that mode dynamics can be described by a quasi stationary force balance including electromagnetic and viscous forces. Both m=0 and m=1 resonant modes are studied. The m=1 modes have rotation velocities corresponding to the plasma flow velocity (20-60 km/s) in the core region. The rotation velocity decreases towards the end of the discharge, although the plasma flow velocity does not decrease. A rotating phase locked m=1 structure is observed with a velocity of about 60 km/s. The m=0 modes accelerate throughout the discharges and reach velocities as high as 150-250 km/s. The observed m=0 phase locking is consistent with theory for certain conditions, but there are several conditions when the dynamics are not described. This is not unexpected because the assumption of quasi stationarity for the mode spectra is not fulfilled for many conditions. Localized m=0 perturbations are formed in correlation with highly transient discrete dynamo events. These perturbations form at the location of the m=1 phase locked structure, but rotate with a different velocity as they spread out in the toroidal direction. (C) 2004 American Institute of Physics.
Place, publisher, year, edition, pages
2004. Vol. 11, no 2, 647-658 p.
madison symmetrical torus, phase-locking, tearing modes, locked modes, wall modes, instabilities, fluctuations, generation, dynamics, rfx
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:kth:diva-23101DOI: 10.1063/1.1639016ISI: 000188282100020ScopusID: 2-s2.0-1242332357OAI: oai:DiVA.org:kth-23101DiVA: diva2:341799
QC 20100525 QC 201110312010-08-102010-08-102011-10-31Bibliographically approved